Thermostat, water pump or head gasket?

[Bobster]

Dazed and confused on this one! 93 Legacy was not prducing heat and I noticed it was running almost in the hot zone! I replaced the thermostat (Lappens Auto parts--cheapo) and then noticed a leak in the radiator header--replaced that too. Still runs hot--so I took out the thermostat and ran it for 1/2 hr or so---ran nice in the midzone...Didn't test the t'stats but wonderin what the next step should be before going out for head gasket /cracked block? repair... I'd love to trust repair joints but don't have a great feeling on this one....SHould I buy the C02 tst kit? No white smoke, no burining antifreeze smell, not sure about oil in the antifreeze (most blew out the radiator crack), haven't drained oil to see if water is present...Any help would be great relief!

[Legacy777]

Replace the thermostat with an OEM subaru thermostat. Aftermarket t-stats don't work right in subies. There's several threads if you want to search.

[DWM650]

DITTO... OEM only on the T/stat. Factory ones are 3 stage. Same goes for the Waterpump use OEM only, or ya be doing it agian soon.

[99obw]

Dazed and confused on this one! 93 Legacy was not prducing heat and I noticed it was running almost in the hot zone!

 

These are classic low coolant symptoms. Start with an OEM thermostat and make sure you get all of the air out of the system.

[bouglas]

Same symptoms recently with my 98 Forester, 120k.

 

Did the whole minor repair route... Coolant level, Tstat, then had'em test for CO in the coolant>>negative, did a radiator hole repair (replacement$$$), while in there did the timing belt & waterpump. Fine for 2 days, then again no heat.

 

Finally took it to Subaru dealer, who did a true diagnostic, HG was fine, had a crack in the block, and a lot of bearing rattle way down deep. Still don't know what caused it all, where that crack originated, (first year they made the Forester?) but it was ultimately a full block replacement.

 

I'm not unhappy... the car cost me $8000 2 years ago, I've put 50k on it, and now I have a great new $4000 engine, it should carry me for another 120k or more.

 

It was just lousy timing on when I had to spend that $4k.

 

Hope your solution is less costly.

-doug

[Legacy777]

Also there is a bleed screw on the passenger side of the radiator to get all the air out of the cooling system.

[richierich]

After you replace the thermostat, it works best if you take the upper radiator hose off of the radiator and fill up the engine with antifreeze till it almost comes out the hose, put the hose back on and tighten it. Then fill up the radiator and overflow bottle. Makes it much harder to get an air bubble in the system that way.

[AaronCarol]

I had something similar happen to me a few months back. No heat, and the engine overheating. Came to the conclusion that I had a bad head gasket because the coolant wouldn't circulate so I figured on an airlock happening. Finally I decided to change the water pump and T-stat only and leave the head gasket. It's tempting to jump to blaming the head gaskets given their notoriety. Plus I did a CO in the coolant test that turned up positive. But I am convinced that these tests don't work right if the coolant is not circulating for two reasons, 1) coolant beside the block starts to boil when it's not circulating and this gives off a gas which can fool the test. 2) coolant can actually back up into the test and mar the results. To make a long story short the water pump was the only culprit because the car is working fine now. The water pump was totally screwed up when I removed it.

 

My recomendation is to change the water pump and T-stat both and see if that solves your problem.

Dazed and confused on this one! 93 Legacy was not prducing heat and I noticed it was running almost in the hot zone! I replaced the thermostat (Lappens Auto parts--cheapo) and then noticed a leak in the radiator header--replaced that too. Still runs hot--so I took out the thermostat and ran it for 1/2 hr or so---ran nice in the midzone...Didn't test the t'stats but wonderin what the next step should be before going out for head gasket /cracked block? repair... I'd love to trust repair joints but don't have a great feeling on this one....SHould I buy the C02 tst kit? No white smoke, no burining antifreeze smell, not sure about oil in the antifreeze (most blew out the radiator crack), haven't drained oil to see if water is present...Any help would be great relief!

[Gnuman]

Is there an echo in here? Well here we go again: do not ever put an aftermarket T-stat in a Subie. Change that out first, with a Genuine Subaru thermostat. With the age of your car, a new waterpump would also be a good idea. Since you have to remove the timing belt to get the waterpump out, how many miles are on it? If you are over half the lifespan of the timing belt, go ahead and replace that while you are in there (this last is a might as well kinda thing).

 

The most likely culprit is the thermostat, however, so that should be changed now. If you want to wait on replacing the waterpump until it is time to change the timing belt, well that is your gamble. When you do, however, do use a genuine Subaru waterpump as well. the aftermarket ones are crap in comparison.

[JT95]

Do some reading up from the in-the-know guys here on eliminating air in your coolant system--it can be a real problem and a real pain in Subaru engines.

 

 

I had my 95 overheating before Christmas. I replaced the thermostat on it. I did not get a factory thermo because it was 8:00 at night, the nearest Subaru dealer is 1.5 hours away regardless, and I needed to get home for the evening and was 30 miles from home. So, I popped in an O'Reiley's replacement thermostat. Kept getting leaks when I'd put everything back and finally used the old O-ring with the new thermostat and no more problems. My engine runs at the same mid-point temp range it used to, so I've not had a problem yet w/ the aftermarket thermo, though I get a factory one if you can. The whole burping the air out of the coolant system was a problem for me--mainly because I'd never experienced it--so it took another day or two to figure out that issue and burp out those pesky air pockets...

[Gnuman]

Each time I burp a Subaru engine, it gets easier. Points to remember are to point the nose uphill as much as you can, then fill from the top radiator hose as much as you can , then connect it to the radiator, and fill from the radiator fill until it is topped off. then start the car and let it warm up. when the fans come on, the car is warm. Keep filling untill you get no more bubbles and the level does not go down. Put the cap on and fill the overflow bottle/tank.open and close the bleeder screw on the top passenger side until there are no bubbles coming out of there either. let it run for a bit and make sure the fans cycle on and off.

[Bobster]

YEEEEHAAA! BURPING WORKS!

Thanks to all of you who helped with my the overheating problem! The OEM t'stat and BURPING did the trick.... I guess I'll be getting another 190,000 miles on this baby.

 

Amazing results. Have to admit..even though it's a simple solution after all's said and done, the head gasket issue was spookin' me. My neighbor has had her 98' subie in the shop for 2 weeks getting a new HG and other "Oh, looks like you need this too!" stuff. Thanks again for your experience and know-how!