Engine problem
1996 Subaru 4 cyl All Wheel Drive Automatic 110000 miles
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Car was overheating. Temp would climb to the top of the guage and then drop quickly indicating a sticking thermostat. I replaced the thremostat and the system passed a pressure test. Any ideas?

Hi there,

Check that the cooling fans are turning on when the temp is high, The radiator may be partially blocked. check these things first.

Mark (mhpautos)

right, sorry. I should have mentioned that the fans are working properly and there are no obstructions to airflow.

It seems like the problem gos in a cycle. There is a big time in between occurances where everything runs perfect. Belts are set properly. Not sure what else to say.

Hi there,

Are there any other constants involved with this overheating? Driving conditions?, ambient temp, Check foe a fault set code as well as an over lean mixture can cause overheating problems

Mark (mhpautos)

It almost seems to do it on a schedule. The is driven 20 miles to work then 20 miles home every day. Every other day on the way home it happens but is limited now to just a few blocks of overheating (gets to near the top of the guage then drops quickly 2-3 times). After this, it is fine whether I keep driving or not. Goofy huh?

Hi there,

If we look at what can cause the temp to fluctuate in this manner there is really only 3 options,

!. Your new thermostat is faulty (not the first one to be)

2. The internal core is partially blocked (but this would normally cause a more constant occurrence)

3, Air pocket in engine, (same as above)

Fan switch is coming on when temp is high? not a problem with a switch that is a bit temperamental?

I would discount a water pup problem at this stage, and one last question, is the coolant level constant, no evidence of loosing any coolant prior to an event?

Mark (mhpautos)

The same thing happens to my Subaru...same year/model/2.5... it happened a few years ago too and I ended up having to replace the radiator.

But Recently it started doing it again and last week my car wouldn't start after stalling for a few days when I would start it.
Not sure if it is related to the overheating thing or if I just got bad gas or something but the problem ended up being 3 fouled spark plugs. They almost looked oil fouled. and since this overheating problem has started happening again a thick white smoke comes from my exhaust when I start it...goes away after a while. Although it happens everytime I stop the engine for over five mins or so...even it the engine is at operating temp.

Just curious if you figured anything out with your problem that could maybe help me.

Thanks