Radiator Fan Not Coming On - Overheating

Another check you could do is to check the thermo switch that control the

Would you be able to tell me where the thermo switch would be? I do
have the Hayes book for this car, but reading an electrical diagram is
not my expertise.

I'm wondered if we can definitely say it IS NOT certain things.
Is there any way it could still be the thermostat, radiator, hoses,
water pump.....the thermostat is brand new. Is there anything else in
the cooling system that could absolutely be written off, or not
written off.

Thanks. Even though this is frustrating and depressing, it's fun to
try to figure it out with your help! Thanks for making this somewhat
enjoyable.

John

 

One more thing I didn't mention. I had taken the radiator hoses off
this weekend and forced water through the top hose to come out of the
bottom hose while the car was off. While I was doing this I heard a
bubbling and hi pitched whistling sound, and saw that it was a very
small amount of radiator fluid was coming out of one of the small
hoses that comes off of the back of the engine and goes right below
where the accellerator is. We're talking less than a drop of fluid,
but air was definitely coming out right there...sorry I didn't mention
it, but it didn't seem important until reading the posts.

THANKS!

John

 

If, as you say, the fans are coming on and going off, and the fluid is
coming out, then going back in, I think you can safely say the thermostatic
switch is OK, the fans are OK, and the thermostat is opening and closing.

If it was a hose, it wouldn't be blasting out into the overflow tank. It
would be streaming out the hose.

So, if we assume the new cap is good, you are building excessive pressure in
the system. The little hoses starting to fail is more evidence of excessive
pressure. I would say it is likely one of the following:

- the head gasket replacement was botched (did it do this before they
replaced it?)

- you have a cracked head or a cracked block.

- timing belt has slipped by a tooth or two (check the timing again). I
think I like this one. This happened to my old VW Rabbit once and the
symptom was exactly as you describe - the cooling system functioned
correctly, but the engine ran rough and it got so hot the fluid just blasted
out through the cap (until the tank cracked). A pebble had gotten under the
timing belt and it slipped by one tooth.

 

That hose cools the head. Putting house water pressure into the engine is
not a good idea. The radiator cap opens at 8-12 psi. Your house supply
could be up to 45 psi. Since the engine is cold, the thermostat is closed.
There would be little flow through the engine.

 

Look for a switch that is connected to the radiator fan.

 

hopefully, its #3 and it happened during reassembly.

any way to test the timing w/ a timing light?

 

You're not looking for ignition timing, but rather valve timing. You need
to pull the cover off the timing belt and see if the marks on the sprockets
(cam and crank) line up correctly.

 

In the Haynes Manual's UK edition, the electrical items are listed
on a page just in front of the circuit diagrams. Find the cooling fan
number in the list. Also look for the fan's thermostatic switch and
note its number.

Now look over the circuit diagrams and use the fan number to locate
the cooling fan. Trace the wiring back to find the switch and confirm
it with the number.

HTH

 

Opps. So you think that hose wouldn't have anything to do with air
getting into the system? Is there a general feeling that the only
thing left is a cracked head or engine block? Is there any
inexpensive way to check this?

Thanks!
John

 

Check for bubbles first. There is no cheap way to check for cracked block/head.

 

Crack into combustion chamber from coolant passage: pressure test.
Crack into cooling system from outside: dye test.
Crack into oil passages from inside: dye test.

These tests are cheap.

--
TeGGeR®

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