On Mar 23, 9:47*am, Transition Zone wrote:
On Mar 21, 4:31*pm, jon_banquer wrote:







On Mar 21, 12:31*pm, Ed Huntress wrote:

On Thu, 21 Mar 2013 14:42:38 -0400, wrote:
On Thu, 21 Mar 2013 08:09:51 -0400, Ed Huntress
wrote:

On Thu, 21 Mar 2013 02:19:21 -0400, "Steve W."
wrote:

Ed Huntress wrote:
On Wed, 20 Mar 2013 18:45:39 -0700 (PDT), jon_banquer
wrote:

On Mar 20, 6:38 pm, Ed Huntress wrote:
On Wed, 20 Mar 2013 18:24:12 -0700 (PDT), jon_banquer

wrote:
On Mar 20, 6:04 pm, Ed Huntress wrote:
On Wed, 20 Mar 2013 19:59:49 -0400, wrote:
On Wed, 20 Mar 2013 11:49:22 -0400, Ed Huntress
wrote:
On Wed, 20 Mar 2013 08:42:16 -0700, "PrecisionmachinisT"
wrote:
"Ken Grunke" wrote in message
....
I am assuming there has to be a separate check valve INLINE between the
plug adapter and the gauge below the release valve. That is what I am
missing. It may be a fitting I had, but absent-mindedly misplaced.
Could be a spring and or check ball is missng or gunked up at the spark plug
fitting end...
--FWIW blowing into the end with your mouth probably won't produce enough
hose expansion to actuate a ball type check valve.
Sorry for jumping into the middle without having read the thread, but
there are two kinds of compression testers: the regular kind, which
have a button to activate the check-release valve; and leak-down
testers, which have no such valve.
I have both. They look almost the same. Perhaps, if Ken's tester
doesn't have a check valve, he has a leakdown tester. If so, it will
have a spark-plug-thread terminal end. Regular testers *may* have such
a thread. Mine just has a tapered rubber plug.
A leakdown tester should have 2 guages and WILL have a connector for
compressed air.
Mine has one gauge. It's around 45 years old. And as I noted in an
addition to the post above, it has a Schrader valve for pumping up the
cylinder.
What's the second gauge for? With mine, you just attach it, make sure
both valves are closed, and pump it up. Test dry, then test wet (with
about an ounce of oil in the cylinder; more for a V-engine).
Is there something else that I've missed?
--
Ed Huntress
One gauge tells you your air input pressure, the other your cylinder
pressure.
I don't understand that. All you care about is the air you get into
the cylinder, right?

I used to do a lot of leakdown tests, and I think I remember how they
were done. All I did was pump the cylinder up to some pressure and
time how long it takes to drop to some lower pressure. Do the test
dry, then wet, in each cylinder. If it falls faster when dry, it's
rings. If it's the same time when wet, it's valves.

Am I missing something?
It's a percentage test with two gauges.

If you have cylinder(s) with major discrepancies you find out where
the air is leaking to.

If you hear air in the exhaust pipe it's a bad exhaust valve.

If you hear air in the intake it's a bad intake valve.

If you hear air in the crankcase (check where oil dipstick is) it's
bad piston rings.

OK, I can see where that's a lot faster, and it actually combines the
equivalent of a regular compression test (sort of) and an
old-fashioned leak-down test.

With the older equipment, you only would do a leak-down test if all
cylinders looked good in the regular test but you had some reason to
believe one or more cylinders still had a problem. You could do both
tests dry and then wet to try to isolate the problem a bit; pressure
loss with a wet cylinder meant a valve or head-gasket problem, so you
had to pull the head in either case.

The only thing I see wrong with the newer device is that it only
checks the rings at TDC, while a conventional compression test will
show a cylinder is off from any problem along the whole stroke -- like
a scored cylinder that isn't scored along the full length of the
stroke (an engine that's been over-revved a lot, or which has a
cracked lower ring). Also, a valve that's out of adjustment, or which
has a sticky lifter, but which is still fully closed at TDC on the
compression stroke, will not show you the valve problem.

Anyway, it's not something I'm likely to do again. I just thought,
mistakenly, that the OP might have been looking at an old-style
leak-down tester. It appears that it was just a missing Schrader valve
stem in a conventional compression tester. That's what we save old
bicycle inner-tubes for -- spare Schrader stems, and gasket material.

Actually you can use a leak-down tester through the entire stroke IF you have the proper
tools to rotate the crank.
So you have to back off the rocker arms or remove the camshaft?

No, you can test it MOST of the way down on the power stroke and *Most
of the way up on the compression stroke. Leakage at the bottom of the
stroke doesn't amount to much as there is never any useable pressure
down there

Ok, I can see that. It would solve a lot for me if I actually tried
one out.

--
Ed Huntress

* The downfall of Usenet is that it's not the resource it once was
for

*learning.

Oh it still is, it just still comes along with the typical trash and
junk (to be thorough).

Many of the better posters have left and are now on web based forums.
In the case of CADCAM many of the better posters have never been on
Usenet and are now on LinkedIn. My CADCAM Technology Leaders group on
LinkedIn hit 550 members yesterday and I expect it to have 1000
members by the end of 2013.