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GRRRR! Cooling system confusion ??!!?!

Posted: Wed Jan 10, 2007 7:57 am
by Bosco
Okay, This is driving me nuts.

I recently dropped a working motor into a 95 Legacy.
I had some overheating problems, so I bought a new Thermostat. (Not OEM)

That didn't change anything, so I removed the radiator and did a "garden hose flow test" on it, and checked the water pump for any signs of problems.
The radiator seemed to flow well and the pump spun fine with no slop or bearing noise.

Then I changed the Head Gaskets.

So now the car does NOT overheat.
The heat blows nice and hot and is consistent.
The Temp gauge stays at about 40% (perfect).
Buuuuut... the radiator cap stays completely cold, and the lower hose as well.

I was pretty sure I burped the system properly. I used the burp screw and was quite patient (squeezing hoses and all that business).

Naturally, I started wondering about the quality of the 5$ aftermarket Thermostat I put in it. So I removed and tested it in a pot of boiling water. It worked fine. So I put it back in. Still does the same thing.
I can drive the car for a half hour or more and get out and pull the radiator cap right off. no heat and no pressure.

I'm starting to get a bit flustered on this one. The only thing I Haven't tried (that I can think of) is removing the T-stat completely, but after testing it, it seems like it is definitely not the problem.
Is it THAT hard to burp the system correctly?

Posted: Wed Jan 10, 2007 2:56 pm
by turboleg
I assume this is an NA application.

I haven't ever had a problem burping the NA engine. One thing I have learned is that it is better to burp some engines several times. driving the car up to operating temperature for a while and then burping it....and repeat. Obviously be careful that the system isn't too hot and pressureized when you do it.

Its interesting that the temp gauge seems to go to the right spot if the radiator isn't getting warm. I wonder if there is an easy way to check the temperature gauge for accuracy.

Wonder if flushing the block would help.

Posted: Fri Jan 12, 2007 12:45 am
by Legacy777
Replace the aftermarket thermostat with an OEM subaru thermostat.

Also, did you open the bleed screw on the top of the passenger side of the radiator.

Posted: Fri Jan 12, 2007 10:39 pm
by Bosco
Legacy777 wrote:Replace the aftermarket thermostat with an OEM subaru thermostat.

Also, did you open the bleed screw on the top of the passenger side of the radiator.
Thanks, I Did both of those things and it seems to be fixed now... Was going to wait a few days before claiming the official victory.