Interesting overheating problem 1991 Subaru Liberty 4wd station wagon.

I can think of an explanation, but it may not be the right one. Let's suppose that when you go out on the freeway, you lose coolant. However, with the high air flow, the radiator is still able to cool the engine. As soon as you slow down, however, you lose the high air flow, and with the low radiator fluid level, the fans can't handle it. What makes me only half-believe this, however, is: the mechanic should have observed the low coolant level and figured this out himself.

Good thought - but it doesnt seem to loose coolant but i will be more observant to see if it does.

The one that amazes me is still the fact that after it heats up at low revs just puting it in nutral and reving it a bit cools it down again !!!!!

(clip) The one that amazes me is still the fact that after it heats up at low

^^^^^^^^^^^^^^^^^^ That suggests the possibility that the water pump is not working at low

rpm. Possibly a loose drive pulley, or a loose impeller?

tx

I made this sugestion earlier to my mechanic and his responce was that the impeller is driven off the timing belt so it either works or it doesnt and if it was loose we would hear it

but ..... I may ask him to check it again.

Fan isn't working. Probably forgot to hook it back up when the head gasket was done.

-Kurt

snipped-for-privacy@hotmail.com wrote:

Perhaps the fan was put in backwards? (Or maybe the leads were hooked up backwards?) I don't know if that's possible on your car. I did it on a VW I had once. The fan was blowing air FORWARDS through the radiator. At a stop, it was fine, and at highways speeds it was fine, but when driving slowly, the airflow from driving and the airflow from the fan cancelled each other out.

Stand in front of the car when the fan is on and feel which way the air blows.

OK sounds almost identical to the problem i had in my 1990 Liberty Wagon.

I had a similar mysterious cooling problem......I replaced the radiator hoses, the thermostat, had the radiator professionally inspected (it was only two years old), etc etc.

After trying everything else, and contrary to the advice of the subaru dealership, i replaced the water pump. That solved the probelm.

Turns out that the water pump was on its last legs and wasnt circulating the water. So, short trips it would be fine, because the water in the block and the small circulation kept everything cool enough...a drive on the freeway was fine, because of the extra airflow...But drive too long and into a headwind and after about 40min it would boil..

The giveaway (once you know your thermostat is fine) is that after driving for a while, the lower radiator hose was still cold. You expect it to be much cooler than the top hose, but not cold.

Hope that gives you a little food for thought :)

Hi Andrew

My mechanic continues to be sure its not the water pump. He tells me that there is no way it can be sending reduced flow throught the system and only cool the system properly when the revs are high.

Do you happen to remember what the problem was with the waterpump ? How did it fail? I have been told it will be au$320 to replace it and have spent enough on the car latly ;-)

Thanks in advance

david

Hi David Unfortunately by the time i actually replaced the water pump i was so over the whole process that i didnt actually keep the water pump to figure out why it failed!

Subaru had pressure tested the system, and the first time they did it there was a tiny pin-hole leak on one of the seals on the water pump. They dismissed it originally.

When i finally had decided that the water pump was the ONLY thing left to replace, the Subaru mechanic i spoke to looked at the report and suggested that the pin whole leak may have been sucking in air occasionally. If it sucks a bit of air in, the impleller cavitates and doesnt pass any water through the system!.....So based on everything else he agreed with my diagnosis.

I bit the bullet asked for it to be replaced and sure enough it worked. I also figured that after 250,000 kms, the waterpump had seen a lot of wear one way or the other!

If you want to compare symptoms and have a chat about it (im in melbourne),...Email me your number at andrew dot garth at aues dot aerospace dot gknplc dot com (sorry, just dont want my work email spammed)

I can totally sympathise with you...sorting out my cooling system took me about 4-6 months and cost a lot of $$ overall

Andrew Garth wrote: (clip)the Subaru mechanic i spoke to looked at the report and suggested that the pin whole leak may have been sucking in air occasionally. If it sucks a bit of air in, the impleller cavitates and doesnt pass any water through the system!(clip) ^^^^^^^^^^^^^^^^^^^ I hate to bring this up now, but do you suppose a drop of epoxy or a piece of tape over the pinhole might have fixed it, or at least verified the diagnosis?

Thanks :-) guess it might have. Compared to the grief it had caused me trying to track down the issue.....the $320 was the best money ever spent :)