I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...ap-13-bar.html
Thought I'd see if anyone else has heard of this. The claim was that
the water pump could create over 30 PSI of pressure. Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...ap-13-bar.html
Thought I'd see if anyone else has heard of this. The claim was that
the water pump could create over 30 PSI of pressure. Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.

On Apr 21, 6:11*pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

On Apr 21, 9:50*pm, "
wrote:
On Apr 21, 6:11*pm, Tony Hwang wrote:





Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar.....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

DONT EVEN THINK ABOUT THIS WITH A CHEVY VENTURE! their engine the 6
cyc one tends to develop super expensive head gasket leaks as is......

some things are best left alone

On Sun, 21 Apr 2013 15:21:32 -0700, Ashton Crusher
wrote:

I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling.


How often does that happen? If it is frequent, you have other
problems that need to be fixed. Last time I had a boil over was
probably in the 1960's or so.

This is not the proper thing to do. The engineers have put a lot of
work into getting the right temperature and pressures and you think
you can do a better job? Really?

On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "
wrote:

On Apr 21, 6:11*pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!
A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..

On Sun, 21 Apr 2013 19:08:23 -0700 (PDT), bob haller
wrote:

On Apr 21, 9:50*pm, "
wrote:
On Apr 21, 6:11*pm, Tony Hwang wrote:





Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

DONT EVEN THINK ABOUT THIS WITH A CHEVY VENTURE! their engine the 6
cyc one tends to develop super expensive head gasket leaks as is......

some things are best left alone
I'd never overpressure anything with a plastic tank rad. Actually I
wouldn't overpressure ANY system.

Most cars have dash board temperature gauges that tell you where the needle should be if the engine is within it's normal operating temperature.

Do you ever find that your temperature gauge is above that normal range and your radiator cap lets go and spews out a bunch of boiling water and steam?

If so there's something else wrong besides your radiator cap not being strong enough to contain the pressure.

On Apr 21, 11:21*pm, Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

The only way to increase the system pressure would be to change the
thermostat to a higher temperature one so increasing temperature as
well as pressure.
You would then have to change the radiator cap too. But changing the
radiator cap alone wouldn't change the pressure but in the event of
engine overheat/pressure would negate the protection it gives.

Very unwise, you may get hoses bursting and engine overheating .
If your engine is overheating there is a problem with the radiator
(blocked) or the thermostat not fully opening.
Possibly slack belt (drives the water pump).
Electric fan (or it's thermostat) if it has one faulty.
Waterways in cylinder block/head blocked/corroded.

On Apr 21, 11:15*pm, wrote:
On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "





wrote:
On Apr 21, 6:11*pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar.....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

*A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..- Hide quoted text -

- Show quoted text -

You might want to rethink that one. Water isn't going to
move through a system without pressure to push it. I wouldn't
expect the pressure to be very high, but there has to be pressure
due to the pump.

As for the question at hand, what is unstated is if there is
actually a problem, ie is the car overheating? If it is, then
finding out the cause of that instead of trying to raise the
boiling point of the coolant via pressure would seem to be
the better approach. For example, if he has a bad thermostat
or collapsing hose, he'd be just covering up the real problem.

On Apr 22, 2:31*am, harry wrote:
On Apr 21, 11:21*pm, Ashton Crusher wrote:





I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

The only way to increase the system pressure would be to change the
thermostat to a higher temperature one so increasing temperature as
well as pressure.

Dumb as ever. The current cap releases pressure at 7 PSI when
the car overheats. He's proposing changing it to 13 PSI so that
when it is overheating, it will not release until that higher pressure
is reached. That results in a higher pressure when overheating
exactly as he claimed and doesn't require changing the thermostat.



You would then have to change the radiator cap too. But changing the
radiator cap alone wouldn't change the pressure but in the event of
engine overheat/pressure would negate the protection it gives.


Dumb as ever. When the engine overheats, which is what he's
specifically concerned about, having that higher pressure cap will
result in higher pressure.



Very unwise, you may get hoses bursting and engine overheating .
If your engine is overheating there is a problem with the radiator
(blocked) or the thermostat not fully opening.
Possibly slack belt (drives the water pump).
Electric fan (or it's thermostat) if it has one faulty.
Waterways in cylinder block/head blocked/corroded.- Hide quoted text -

- Show quoted text -

That part is correct. Even a stopped clock is occasionally correct.

"Ashton Crusher" wrote in message
news
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...ap-13-bar.html
Thought I'd see if anyone else has heard of this. The claim was that
the water pump could create over 30 PSI of pressure. Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Lots of comments--my two cents: First of all, the water pump is a
centrifugal pump and as such the pressure rise across the pump is a function
of it's speed. The flow output of the pump is a function of the system
characteristics-- Pressure drop vs Flow So changing pressure caps and
thermostats will not change the operating behavior of the pump. The purpose
of the pressure cap is to raise the boiling point of the fluid. This allows
you to run the coolant at higher temperatures (greater than 212F) without
causing it to boil. Just because you have a 180 deg thermostat doesn't mean
that the coolant at running at 180 deg-----because of the cap, typically,
the coolant boiling point is closer to 234 deg F (or higher). That's why
they say never to remove the cap until the coolant cools down--if you remove
the cap too soon, the system pressure becomes 15 psia (atmospheric). the
boiling point becomes 212F and you get a great big flash of steam as the
coolant immediately changes from a liquid to a vapor. As the coolant
temperature increases, it's density (Specific Gravity) decreases and because
it's weight remains constant, the only other variable is it's volume which
increases. Because the cooling system volume is fixed the coolant pressure
will increase (no room to expand) from atmospheric to whatever the cap is
set for and then it is vented to the over-flow bottle.
The downside of increasing the pressure cap setting over what's specified is
two fold---At the higher cap setting, all the system components will be
subjected to pressures beyond design intent--not a good idea. The same
applies to the operating temperature. In summer like days the coolant
temperature will go beyond normal design intent. In both cases, you're
moving in a direction to accelerate component failures.
MLD

Thoughts?????

One other possibility is you may have a blown head gasket.

On Apr 22, 11:57*am, harry wrote:
Thoughts?????

One other possibility is you may have a blown head gasket.

The other very real possibility is that harry is the village idiot,
as has been proven time and time again.

On Sun, 21 Apr 2013 23:31:02 -0700 (PDT), harry
wrote:

On Apr 21, 11:21*pm, Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

The only way to increase the system pressure would be to change the
thermostat to a higher temperature one so increasing temperature as
well as pressure.

Harry, you are incorrect on this. The cap alone WILL cause most
suystems to run at a higher pressure as long as the vehicle runs at a
minimum of 160F. The thermostat only controls the MINIMUM operating
temperature of an engine, so even an engine with a 160 thermostat can
run at 195F, or higher. The cap allows the pressure to build to a
MAXIMUM of the rated pressure - at which point it releases into the
overflow to regulate the pressure.
You would then have to change the radiator cap too. But changing the
radiator cap alone wouldn't change the pressure but in the event of
engine overheat/pressure would negate the protection it gives.

Very unwise, you may get hoses bursting and engine overheating .
If your engine is overheating there is a problem with the radiator
(blocked) or the thermostat not fully opening.
Possibly slack belt (drives the water pump).
Electric fan (or it's thermostat) if it has one faulty.
Waterways in cylinder block/head blocked/corroded.

Or bad timing, or bad mixture, or simply overloading the engine. But
yes, you got ONE thing right - installing a cap with a pressure higher
than the system is designed for CAN cause problems with hoses,
radiators, heater cores, etc..

On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.
Which WILL cause the pressure to increase rapidly if it is causing an
overheating problem - and even a 30psi cap would vent under these
conditions

On Sunday, April 21, 2013 3:21:32 PM UTC-7, Ashton Crusher wrote:

I was thinking of putting a higher pressure cap on one of
my cars to increase the factor of safety against boiling.
Looking thru the web for info on the likelihood of
changing from 7 psi to 13 psi causing leaks I found
little on that issue but did find a couple references to
the pressures created by the water pump. One site
boasts of a 19 PSI, $25 cap to get you thru your
"hard driving".
http://www.mishimoto.com/mishimoto-h...ap-13-bar.html

I live in Arizona, and nobody in my family here has ever
had an overheating problem that wasn't caused by a burst
hose or bad radiator cap, and I know the latter happened
in fall or winter. The hose that broke was a flex hose --
never use those if you don't have to. The bad radiator
caps were brand new replacements -- 2 in a row gushed
out coolant on day one, while the ~5-year-old factory
original cap and a replacement from a car dealer
worked fine. Also I once bought 3 bad thermostats in a
row -- when I tested them in a pot of hot water with a
thermostat, one wouldn't open more than 1/4", the other
two opened wide at about 150F (rated 195F). So for
radiator caps and thermostats, I use only OEM.

On Mon, 22 Apr 2013 05:29:32 -0700 (PDT), "
wrote:

On Apr 21, 11:15*pm, wrote:
On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "





wrote:
On Apr 21, 6:11*pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

*A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..- Hide quoted text -

- Show quoted text -

You might want to rethink that one. Water isn't going to
move through a system without pressure to push it. I wouldn't
expect the pressure to be very high, but there has to be pressure
due to the pump.

As for the question at hand, what is unstated is if there is
actually a problem, ie is the car overheating? If it is, then
finding out the cause of that instead of trying to raise the
boiling point of the coolant via pressure would seem to be
the better approach. For example, if he has a bad thermostat
or collapsing hose, he'd be just covering up the real problem.

No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it. Just to give a bigger margin of safety when the
temps here get up to 110. The manual for the car lists the 7 pound
cap for non-ac cars and the 13 pound cap for AC cars. Just curious if
anyone has ever seen this increase in pressure cause an immediate leak
to happen. The Radiator was rebuilt 10 years/10,000 miles ago. The
heater core is factory original. Now, on a 95 degree day it's running
up to 205 on the freeway and 195 around town. Thermostat is 180.

On Sun, 21 Apr 2013 22:40:35 -0400, Ed Pawlowski wrote:

On Sun, 21 Apr 2013 15:21:32 -0700, Ashton Crusher
wrote:

I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling.


How often does that happen? If it is frequent, you have other
problems that need to be fixed. Last time I had a boil over was
probably in the 1960's or so.

This is not the proper thing to do. The engineers have put a lot of
work into getting the right temperature and pressures and you think
you can do a better job? Really?

It would just change it to the pressure for AC cars. For it's first
52 years of use it was without AC. I added AC to it.

On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.

I didn't want to make the original post into a novel but it appears a
lot is being read into what wasn't included. That car is not having
any problems at all right now. I'm just looking at increasing the
factor of safety against overheating because I just added AC to it.
Non-ac cars use a 7 pound cap and AC uses 13. But it's a 52 year old
car (well maintained) and the downside would be if adding 6 pounds
more pressure is likely to create any leaks, like in the 52 year old
heater core. Nothing leaks now. I'm just torn between being
proactive and getting a higher pressure cap "just in case", or just
sitting tight and seeing how the temperatures run as the weather heats
up.

On Mon, 22 Apr 2013 11:23:19 -0700 (PDT),
wrote:

On Sunday, April 21, 2013 3:21:32 PM UTC-7, Ashton Crusher wrote:

I was thinking of putting a higher pressure cap on one of
my cars to increase the factor of safety against boiling.
Looking thru the web for info on the likelihood of
changing from 7 psi to 13 psi causing leaks I found
little on that issue but did find a couple references to
the pressures created by the water pump. One site
boasts of a 19 PSI, $25 cap to get you thru your
"hard driving".
http://www.mishimoto.com/mishimoto-h...ap-13-bar.html

I live in Arizona, and nobody in my family here has ever
had an overheating problem that wasn't caused by a burst
hose or bad radiator cap, and I know the latter happened
in fall or winter. The hose that broke was a flex hose --
never use those if you don't have to. The bad radiator
caps were brand new replacements -- 2 in a row gushed
out coolant on day one, while the ~5-year-old factory
original cap and a replacement from a car dealer
worked fine. Also I once bought 3 bad thermostats in a
row -- when I tested them in a pot of hot water with a
thermostat, one wouldn't open more than 1/4", the other
two opened wide at about 150F (rated 195F). So for
radiator caps and thermostats, I use only OEM.


I'm in Phoenix area and my experience is the same as far as
overheating but I've never had this low a pressure cap (7 psi) before.
A 13 pound cap would give me another 14 degrees before boil over. I
just added AC and that seems to have raised the temp baseline by 10
degrees once the weather is over 90.

I'm in Phoenix area and my experience is the same as far as
overheating but I've never had this low a pressure cap (7 psi) before.
A 13 pound cap would give me another 14 degrees before boil over. *I
just added AC and that seems to have raised the temp baseline by 10
degrees once the weather is over 90.

the higher pressure cap may give you more margin to boil over but will
give you less margin to springing a leak... so take your pick...

here's an idea..

keep a few gallons of water in the trunk ( a good idea anyway in
phoenix) along with the high pressure radiator cap. Keep the low
pressure cap on the car for normal use which puts the least strain on
the old plumbing. You'll have the high pressure cap and extra water
in the trunk for backup.

Mark

On Mon, 22 Apr 2013 15:13:39 -0700 (PDT), Mark
wrote:


I'm in Phoenix area and my experience is the same as far as
overheating but I've never had this low a pressure cap (7 psi) before.
A 13 pound cap would give me another 14 degrees before boil over. *I
just added AC and that seems to have raised the temp baseline by 10
degrees once the weather is over 90.

the higher pressure cap may give you more margin to boil over but will
give you less margin to springing a leak... so take your pick...

here's an idea..

keep a few gallons of water in the trunk ( a good idea anyway in
phoenix) along with the high pressure radiator cap. Keep the low
pressure cap on the car for normal use which puts the least strain on
the old plumbing. You'll have the high pressure cap and extra water
in the trunk for backup.

Mark



I was sort of toying with that approach. Probably will be what I wind
up doing.

Ashton,


No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it.

I don't follow this. Your radiator is running about 10 deg. F (?) hotter
with the AC, so what? Why is that a problem? You aren't anywhere near the
boiling point of your coolant, are you? Assuming you have a 50:50 mixture
and 7 psi your boiling point is about 255 deg. Changing to a 13 psi cap
would improve things by raising the boiling point to about 270 deg.
Unless you are getting close to 250 I don't understand why you want to do
this. Be sure to check my math. These figures are quick guesstimates.
Sorry, sounds like a waste of money. Keep an eye on the temp gauge this
Summer though till you're sure.

Dave M.

On Mon, 22 Apr 2013 19:40:05 -0400, "David L. Martel"
wrote:

Ashton,


No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it.

I don't follow this. Your radiator is running about 10 deg. F (?) hotter
with the AC, so what? Why is that a problem? You aren't anywhere near the
boiling point of your coolant, are you? Assuming you have a 50:50 mixture
and 7 psi your boiling point is about 255 deg. Changing to a 13 psi cap
would improve things by raising the boiling point to about 270 deg.
Unless you are getting close to 250 I don't understand why you want to do
this. Be sure to check my math. These figures are quick guesstimates.
Sorry, sounds like a waste of money. Keep an eye on the temp gauge this
Summer though till you're sure.

Dave M.


So far it's not a problem. I've just never run anything with such a
low pressure cap before. Some of my newer cars will run upwards of
235 on really hot days so I'm wondering if this one does will the 250
be enough of a cushion.

"David L. Martel" wrote in message
...
Ashton,


No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it.

I don't follow this. Your radiator is running about 10 deg. F (?) hotter
with the AC, so what? Why is that a problem? You aren't anywhere near the
boiling point of your coolant, are you? Assuming you have a 50:50 mixture
and 7 psi your boiling point is about 255 deg. Changing to a 13 psi cap
would improve things by raising the boiling point to about 270 deg.
Unless you are getting close to 250 I don't understand why you want to
do this. Be sure to check my math. These figures are quick guesstimates.
Sorry, sounds like a waste of money. Keep an eye on the temp gauge this
Summer though till you're sure.

Dave M.

There is noting wrong with your logic. The coolant is already being ported
into the overflow tank with the OEM pressure cap. Putting in a cap that
cracks at a higher pressure probably won't even change anything with respect
to when the coolant starts to go into the overflow tank. In a closed system
(completely full and cap shut) the coolant pressure increases rapidly as the
fluid starts expanding (without the cap opening the pressure could easily
get up to a 1000 psi). Going from 7 to 15 psi would have a relatively
insignificant change in the way things work. It doesn't change the
operating temperature, just raises the boiling point of the coolant. And
operating at a higher pressure than OEM is moving in a trouble direction.
BTW, one can calculate pressure vs temperature in a closed system--just look
up "Bulk Modulus" and fluid compressibility.
MLD

On Mon, 22 Apr 2013 11:44:02 -0700, Ashton Crusher
wrote:




It would just change it to the pressure for AC cars. For it's first
52 years of use it was without AC. I added AC to it.

If that is factory spec, it should be OK. OTOH, since it is over 50
years old, I'd not want to increase pressure if I did not have to.

On Mon, 22 Apr 2013 19:40:05 -0400, "David L. Martel"
wrote:

Ashton,


No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it.

I don't follow this. Your radiator is running about 10 deg. F (?) hotter
with the AC, so what? Why is that a problem? You aren't anywhere near the
boiling point of your coolant, are you? Assuming you have a 50:50 mixture
and 7 psi your boiling point is about 255 deg. Changing to a 13 psi cap
would improve things by raising the boiling point to about 270 deg.
Unless you are getting close to 250 I don't understand why you want to do
this. Be sure to check my math. These figures are quick guesstimates.
Sorry, sounds like a waste of money. Keep an eye on the temp gauge this
Summer though till you're sure.

Dave M.

13 psi on a '60 mopar pretty well guarantees you will have some
expensive cooling system repairs in your future. If you are worried,
which you should not be, put on an electric fan in front of the
rad/condensor.

On 4/22/2013 8:51 PM, wrote:
On Mon, 22 Apr 2013 19:40:05 -0400, "David L. Martel"
wrote:

Ashton,


No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it.

I don't follow this. Your radiator is running about 10 deg. F (?) hotter
with the AC, so what? Why is that a problem? You aren't anywhere near the
boiling point of your coolant, are you? Assuming you have a 50:50 mixture
and 7 psi your boiling point is about 255 deg. Changing to a 13 psi cap
would improve things by raising the boiling point to about 270 deg.
Unless you are getting close to 250 I don't understand why you want to do
this. Be sure to check my math. These figures are quick guesstimates.
Sorry, sounds like a waste of money. Keep an eye on the temp gauge this
Summer though till you're sure.

Dave M.

13 psi on a '60 mopar pretty well guarantees you will have some
expensive cooling system repairs in your future. If you are worried,
which you should not be, put on an electric fan in front of the
rad/condensor.


My 1965 Dodge Dart used a 13psi radiator cap on the good old Slant Six
radiator, at least that's what the part look up states. o_O

TDD

On Mon, 22 Apr 2013 21:44:28 -0400, Ed Pawlowski wrote:

On Mon, 22 Apr 2013 11:44:02 -0700, Ashton Crusher
wrote:




It would just change it to the pressure for AC cars. For it's first
52 years of use it was without AC. I added AC to it.

If that is factory spec, it should be OK. OTOH, since it is over 50
years old, I'd not want to increase pressure if I did not have to.
Actually, the spec is14psi on the 60, but I often put a lower
pressure cap on an older car to protect the rad. If the rad is solid,
and the heater core is solid, and the hoses are good, you should be ok
with the 14 lb cap. But that's a big if.

If the temperature is well under 210F with the air on, you don't need
the heavy cap - and that's not nearly as big an if, generally
speaking.

Ed Pawlowski wrote:
On Sun, 21 Apr 2013 15:21:32 -0700, Ashton Crusher
wrote:

I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling.


How often does that happen? If it is frequent, you have other
problems that need to be fixed. Last time I had a boil over was
probably in the 1960's or so.

This is not the proper thing to do. The engineers have put a lot of
work into getting the right temperature and pressures and you think
you can do a better job? Really?

Hi,
As well today's cars are monitored and controlled by computers. Better
not fool around.

On Apr 22, 6:07*pm, "
wrote:
On Apr 22, 11:57*am, harry wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.

The other very real possibility is that harry is the village idiot,
as has been proven time and time again.

Exhaust gases from a slight head gasket leak will boil the water and
over pressure the system.
You don't really know much do you?

On Mon, 22 Apr 2013 22:53:32 -0700 (PDT), harry
wrote:

On Apr 22, 6:07*pm, "
wrote:
On Apr 22, 11:57*am, harry wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.

The other very real possibility is that harry is the village idiot,
as has been proven time and time again.

Exhaust gases from a slight head gasket leak will boil the water and
over pressure the system.
You don't really know much do you?
Actually the gasses from the leak pressurize the system, blowing the
water out - which causes overheating. Harry doesn't know much either.

Been proven many times.

On 04/22/2013 02:42 PM, Ashton Crusher wrote:
On Mon, 22 Apr 2013 05:29:32 -0700 (PDT), "
wrote:

On Apr 21, 11:15 pm, wrote:
On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "





wrote:
On Apr 21, 6:11 pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. The claim was that
the water pump could create over 30 PSI of pressure. Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..- Hide quoted text -

- Show quoted text -

You might want to rethink that one. Water isn't going to
move through a system without pressure to push it. I wouldn't
expect the pressure to be very high, but there has to be pressure
due to the pump.

As for the question at hand, what is unstated is if there is
actually a problem, ie is the car overheating? If it is, then
finding out the cause of that instead of trying to raise the
boiling point of the coolant via pressure would seem to be
the better approach. For example, if he has a bad thermostat
or collapsing hose, he'd be just covering up the real problem.

No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it. Just to give a bigger margin of safety when the
temps here get up to 110. The manual for the car lists the 7 pound
cap for non-ac cars and the 13 pound cap for AC cars. Just curious if
anyone has ever seen this increase in pressure cause an immediate leak
to happen. The Radiator was rebuilt 10 years/10,000 miles ago. The
heater core is factory original. Now, on a 95 degree day it's running
up to 205 on the freeway and 195 around town. Thermostat is 180.


Do the A/C cars come with a different radiator than non-A/C cars?

given the info you give I would think that this should be OK assuming
everything is in tip-top shape. However you may end up replacing the
heater core if there's a weak spot in it, likewise with any old hoses.

You may also want to consider retrofitting a coolant recovery bottle
like modern cars, that way you won't have to constantly keep an eye on
the radiator's water level, and due to not having any air in the system,
should theoretically make it slightly more resistant to corrosion
(although I'd still change the coolant every two years anyway just for
insurance.) You'd need the proper radiator cap for that, so the
radiator can suck coolant back in through the overflow tube when it
cools down.

good luck

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 04/22/2013 02:31 AM, harry wrote:
On Apr 21, 11:21 pm, Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. The claim was that
the water pump could create over 30 PSI of pressure. Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

The only way to increase the system pressure would be to change the
thermostat to a higher temperature one so increasing temperature as
well as pressure.
You would then have to change the radiator cap too. But changing the
radiator cap alone wouldn't change the pressure but in the event of
engine overheat/pressure would negate the protection it gives.

What? you haven't any clue how a cooling system works do you? Please
just shut up if you don't have any knowledge of what the **** you're
talking about.

nate


--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 04/22/2013 02:50 PM, Ashton Crusher wrote:
On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.

I didn't want to make the original post into a novel but it appears a
lot is being read into what wasn't included. That car is not having
any problems at all right now. I'm just looking at increasing the
factor of safety against overheating because I just added AC to it.
Non-ac cars use a 7 pound cap and AC uses 13. But it's a 52 year old
car (well maintained) and the downside would be if adding 6 pounds
more pressure is likely to create any leaks, like in the 52 year old
heater core. Nothing leaks now. I'm just torn between being
proactive and getting a higher pressure cap "just in case", or just
sitting tight and seeing how the temperatures run as the weather heats
up.


Like I said in a previous post, a coolant recovery bottle would be my
first step... I never did like seeing that air gap at the top of the
radiator, and it's not good for anything to have it there.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On Mon, 22 Apr 2013 11:42:25 -0700, Ashton Crusher
wrote:

On Mon, 22 Apr 2013 05:29:32 -0700 (PDT), "
wrote:

On Apr 21, 11:15*pm, wrote:
On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "





wrote:
On Apr 21, 6:11*pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

*A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..- Hide quoted text -

- Show quoted text -

You might want to rethink that one. Water isn't going to
move through a system without pressure to push it. I wouldn't
expect the pressure to be very high, but there has to be pressure
due to the pump.

As for the question at hand, what is unstated is if there is
actually a problem, ie is the car overheating? If it is, then
finding out the cause of that instead of trying to raise the
boiling point of the coolant via pressure would seem to be
the better approach. For example, if he has a bad thermostat
or collapsing hose, he'd be just covering up the real problem.

No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it. Just to give a bigger margin of safety when the
temps here get up to 110. The manual for the car lists the 7 pound
cap for non-ac cars and the 13 pound cap for AC cars. Just curious if
anyone has ever seen this increase in pressure cause an immediate leak
to happen. The Radiator was rebuilt 10 years/10,000 miles ago. The
heater core is factory original. Now, on a 95 degree day it's running
up to 205 on the freeway and 195 around town. Thermostat is 180.

That should mean the thermostat is wide open. But the thermostat
could be broken. You can replace it, or hang this one into a pot of
water whose temp is climing. Use a candy thermometer or something
that goes up to 190 to see if the thermostat opens all the way at 180.

I've only done this once, and I don't remember how sure I was that it
was open, or not open, all the way. That is, I didn't know where all
the way was, in practical terms.

Maybe you need a trailer package. Well, just the bigger radiator.

Plus what Dave L said.

Heater cores in many many cars are a pain to replace. Lots of things
on top of them, including parts of your recently added AC, which iiuc
doesn't use rubber hoses, uses metal hoses. Am I right about that?

On Mon, 22 Apr 2013 11:50:28 -0700, Ashton Crusher
wrote:

On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.

I didn't want to make the original post into a novel but it appears a

Making a big mistake. I've already shopped it to a publicsher, and
he's discussed it with a NY producer. Since you hadn't even though
of it, I'll take 17 percent. Contact me at Telex;723345.

lot is being read into what wasn't included. That car is not having
any problems at all right now. I'm just looking at increasing the
factor of safety against overheating because I just added AC to it.

Your conflating over-pressure with over-heating. Containing the
pressure won't make it cooler.

Non-ac cars use a 7 pound cap and AC uses 13. But it's a 52 year old
car (well maintained) and the downside would be if adding 6 pounds
more pressure is likely to create any leaks, like in the 52 year old
heater core. Nothing leaks now. I'm just torn between being
proactive and getting a higher pressure cap "just in case", or just
sitting tight and seeing how the temperatures run as the weather heats
up.

On Apr 25, 4:45*pm, micky wrote:
On Mon, 22 Apr 2013 11:50:28 -0700, Ashton Crusher
wrote:

On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
wrote:

Thoughts?????

One other possibility is you may have a blown head gasket.

I didn't want to make the original post into a novel but it appears a

Making a big mistake. *I've already shopped it to a publicsher, and
he's discussed it with a NY producer. * Since you hadn't even though
of it, I'll take 17 percent. * Contact me at Telex;723345.

lot is being read into what wasn't included. *That car is not having
any problems at all right now. *I'm just looking at increasing the
factor of safety against overheating because I just added AC to it.

Your conflating over-pressure with over-heating. * Containing the
pressure won't make it cooler.



Non-ac cars use a 7 pound cap and AC uses 13. *But it's a 52 year old
car (well maintained) and the downside would be if adding 6 pounds
more pressure is likely to create any leaks, like in the 52 year old
heater core. *Nothing leaks now. *I'm just torn between being
proactive and getting a higher pressure cap "just in case", or just
sitting tight and seeing how the temperatures run as the weather heats
up.

adding a transmission oil cooler is probaly a good idea with a
transmission oil filter in series it might save a expensive
transmission rebuid someday

On Thu, 25 Apr 2013 16:38:42 -0400, micky
wrote:

On Mon, 22 Apr 2013 11:42:25 -0700, Ashton Crusher
wrote:

On Mon, 22 Apr 2013 05:29:32 -0700 (PDT), "
wrote:

On Apr 21, 11:15*pm, wrote:
On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "





wrote:
On Apr 21, 6:11*pm, Tony Hwang wrote:
Ashton Crusher wrote:
I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. *Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. *One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
Thought I'd see if anyone else has heard of this. *The claim was that
the water pump could create over 30 PSI of pressure. *Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. *If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline * and created another 30psi of additional pump pressure, or
even 10 psi of additioingnal pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. * I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.- Hide quoted text -

- Show quoted text -

AMEN!

*A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..- Hide quoted text -

- Show quoted text -

You might want to rethink that one. Water isn't going to
move through a system without pressure to push it. I wouldn't
expect the pressure to be very high, but there has to be pressure
due to the pump.

As for the question at hand, what is unstated is if there is
actually a problem, ie is the car overheating? If it is, then
finding out the cause of that instead of trying to raise the
boiling point of the coolant via pressure would seem to be
the better approach. For example, if he has a bad thermostat
or collapsing hose, he'd be just covering up the real problem.

No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it. Just to give a bigger margin of safety when the
temps here get up to 110. The manual for the car lists the 7 pound
cap for non-ac cars and the 13 pound cap for AC cars. Just curious if
anyone has ever seen this increase in pressure cause an immediate leak
to happen. The Radiator was rebuilt 10 years/10,000 miles ago. The
heater core is factory original. Now, on a 95 degree day it's running
up to 205 on the freeway and 195 around town. Thermostat is 180.

That should mean the thermostat is wide open. But the thermostat
could be broken. You can replace it, or hang this one into a pot of
water whose temp is climing. Use a candy thermometer or something
that goes up to 190 to see if the thermostat opens all the way at 180.


I've checked it (with infrared thermo gun) quite a few times even
before putting the AC on it and it seems that the car, in cool
weather, runs up to 180 and stays there as it should with a 180
thermo. In hotter weather it would go up to around 190-195 on the
freeway. Now with the AC it's added about 10 degrees but still has a
lower plateau at 180.


I've only done this once, and I don't remember how sure I was that it
was open, or not open, all the way. That is, I didn't know where all
the way was, in practical terms.


I've checked several and a few were bad and would only open about 1/8
inch. Good ones open maybe half an inch.

Maybe you need a trailer package. Well, just the bigger radiator.

Plus what Dave L said.

Heater cores in many many cars are a pain to replace. Lots of things
on top of them, including parts of your recently added AC, which iiuc
doesn't use rubber hoses, uses metal hoses. Am I right about that?


Since this is an added ac it won't interfere much with the original
heater. Here in AZ it's not unusual for bad heater cores to just be
bypassed :-)