On Sat, 10 Aug 2013 00:34:42 -0700, "Guv Bob"
wrote:

"Ashton Crusher" wrote in message ...
On Fri, 9 Aug 2013 21:58:01 -0700, "Guv Bob"
wrote:

"Ashton Crusher" wrote in message ...
On Wed, 7 Aug 2013 16:06:52 -0700, "Guv Bob"
wrote:

"Ashton Crusher" wrote in message ...
On Mon, 29 Jul 2013 09:24:41 -0700, "Guv Bob"
wrote:

wrote in message news On Sat, 27 Jul 2013 15:14:29 -1000, Geoff Welsh
wrote:

Guv Bob wrote:
....The cooling system has been starting to overheat for the
past few months when it's a idling for more than a couple of minutes.
.....


I fail to understand why you are worried about colors and noises on a
vehicle that is constantly overheating.

Have you had a block test done?

GW
As I stated - if the pH of the coolant is too high the radiator will
scale and it will NOT cool properly. If the pH is too low (acidic) the
radiator will corrode and leak.

If it overheats at idle but not on the road the primary suspect is the
fan clutch. Next suspect is a restricted rad (which would usually also
heat under heavy load) - (either air restriction or restricted coolant
flow)

Thanks, you mentioned this before. Fan clutch works fine. Radiator is not restricted.

What makes you say the fan clutch works fine? I've been thru this
with a 90 ford mustang and the difference between the old one (that
wasn't working fine) and the new (that solved the runs hot at idle
problem) was almost imperceptible by feeling anything by hand or
looking at anything.

The fan spins freely when cold. Then after the engine's hot and I turn it off, there's a pretty good resistance to spinning.

Also, I can put a white mark on one of the fan blades, the fire the engine up to idle speed and then turn it off, and count the revolutions until it stops. Doing the same thing when hot, it stops quicker.


Yours could be fine, like I said the difference between Fine and not
fine can be pretty small. If it's not overheating at speed and is at
idle there isn't a whole lot of things that would cause that but a
problem with the fan. And the fan is usually the easiest thing to
replace when you have reached the point where you can't pin down
anything and are ready to start throwing parts at it. OTOH, at least
theoretically, there could be some kind of ignition timing problem
that's got the engine idling with the wrong spark advance and making
up for it by adjusting the idle speed to compensate. I would tend to
think that ought to throw a code though.

Well, you're probably right in my case, AC. Today it spins the same whether hot or cold. I've been told that these after-market fan clutches are prone to fail early. I changed it once and was a lot easier than a water pump.

I assume the idea behind having a clutch is that it lets the engine warm up quickly and then starts to cool when hot. What do you think about bolting the clutch in place so that the fan always spins the same?


My Dad did that years ago. Not a good idea. The front bearing of his
water pump greeted him one day soon after he bolted thru clutch in
place. The deal with the clutch is that it never spins more then
about 2500 rpm even if the engine is going faster. Plus it's
balanced. Bolt in together and you probably will throw the balance
off and you surely will wind up revving it up past it's design speed.

OK, thanks for the good advice. The last fan clutch is less than a few months old. Can you recommend any particular brand?
Actually they will run up pretty close to full speed when hot and
running steady speed. I'd switch to an electric fan if I was having
fan clutch problems.