HELP! AX OVERHEATING

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Sat 13 Oct 2001 10:16
HELP! AX OVERHEATING - Phil Goodacre
I hope all you knowledgeable folk out there can point me in the right direction regarding my sons AX. Please, no scrapyard addresses. The car is a 92 1.0 with 80k on the clock. No sign of any leaks, no mayo present. Overheating is pretty rapid, within 10 minutes of start up. Warning light comes on, electric fan does not kick in and although the top hose is very hot, the bottom hose remains cold. Hot coolant is then forced out of the radiator filler cap. Could it be someting as simple as a blocked radiator core or even the stat? The heater blows hot by the way, so not the heater matrix.
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Sat 13 Oct 2001 11:10
Re: HELP! AX OVERHEATING - David W
Phil,

Likely to be as simple as a failed thermostat if you are lucky. One clue is the fact it happens so quickly, another that the top hose feels hot but the bottom one cold. What happens is the water in the top hose gets quite hot from heat conduction rather than water flow.

I've known this to catch folk out saying "it can't be the stat because the hose is hot", but they don't check lower down. One chap came to me for a quote on a P.405 head gasket because his garage had diagnosed that as failed (his symptoms were identical to yours) and quoted about £350. I tested as above, replaced the stat and he was away for a pittance.

Try this first then come back to us.

If that doesn't do it we could be looking at a blocked rad, water pump impellor spinning on shaft....but lets not go there yet!

David
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Sat 13 Oct 2001 12:08
Re: HELP! AX OVERHEATING - Phil Goodacre
Thanks David, I'll try that this afternoon and let you know.
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Sat 13 Oct 2001 19:17
Re: HELP! AX OVERHEATING - Darcy Kitchin
David,
Genuine search for knowledge, not nitpicking, but how is the heater matrix getting hot water if the thermostat is stuck?

Phil,
We run an AX diesel so would be interested in knowing history. Were the symptoms sudden, or gradual. Any other events, like a visit to the garage?
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Sat 13 Oct 2001 19:27
Re: HELP! AX OVERHEATING - Simon
The heater matrix and associated pipe work does not run through the thermostat, it is independant of that

If it did you would only be able to get hot air through your heater once the engine had fully warmed up to the correct operating temperature and the thermostat had opened and not as soon as the water started get hot from the engine.

You would soon notice this first thing in the morning if you had to drive quite a few miles before you could get any hot air at all inside your car.
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Mon 15 Oct 2001 11:59
Re: HELP! AX OVERHEATING - Phil Goodacre
Thermostat it was. Changed it Saturday pm and the problem is cured.
Darcy, regret I don't know history as the car is my sons and as I am always criticising his driving, he didn't tell me, his mate let it slip in conversation. The overheating had been going on for a few weeks, he just stopped until it cooled down and then carried on. The heater was certainly blowing warm air which is what confused me, hence the cry for help.
Many thanks for the help David.
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