Cooling issue, pushing into overflow.

[Thomistopheles]

Previous owner of my 97 OB said it needed a radiator and had to be filled every 70 miles. She was full of crap, so I'm here to poke at SLi's collective brain to figure out what's going on with it.

There is no coolant in the oil, no oil in the coolant.
The car does not smoke, the exhaust does not smell like it is burning coolant.
The fans kick on properly.
The radiator is brand new, along with the cap and upper + lower hoses.
I have not replaced the thermostat.
No visible leaks other than when the overflow overflows, nothing on the pavement under the car.

The car gets up to operating temp and stays there for a good while, but eventually it pushes coolant into the overflow and does not suck it back in. When it cools and I remove the radiator cap, it is low and needs to be filled. It doesn't get hot until it pushes a bunch of fluid out and the rad is low.

What do you think... head gasket letting air/exhaust into the cooling system? Bad thermostat? Sneaky leaky hose?

please be the thermostat please be the thermostat please be the thermostat please be the thermostat please be the thermostat

[mike-tracy]

Replace thermostat with brand new OEM one and go from there. Aftermarket ones just don't "work" in these cars, with very few exceptions.

[Thomistopheles]

Yep, I read about that when I was looking into the Grimmspeed thermostat. I'll stick with the OEM one. I called this morning to check if my local dealer stocks them and they do, so I'll grab one in the morning.

[mike-tracy]

So bleeding the air out of a Subaru is harder than other cars I've dealt with. It usually takes me several times of filling up the upper radiator hose with coolant, topping up at the radiator cap (with the bleeder valve open). Getting the car up to temperature with hot air blowing full blast, letting it cool down and repeat. I always jack up the front end or park it facing upwards on a hill.

[chrish8r]

I know you pretty much ruled out some blown head gaskets, but that is what is happening to mine.....

[Okin DaVanh]

I know you pretty much ruled out some blown head gaskets, but that is what is happening to mine.....


And thats what happened to me too... :smt009 The PO only had 1 of the heads checked and tanked, but it turned out to be both heads

[Thomistopheles]

Nah, I didn't rule out the head gaskets. I'm 99% sure that's what it is...an internal HG leak letting air/exhaust into the cooling system.

[chrish8r]

Oh okay cause mine is an internal leak as well...but i have the exhaust smoke as well....i turn my defroster on high all the time and i can usually go a little bit longer than usual before it overheats

[Thomistopheles]

Mine doesn't overheat (I keep filling the radiator to replace what it pushes into the overflow) and there's none of the usual signs of a blown head gasket... no smoke, no coolant in the oil, no oil in the coolant. It's weird.

[Thomistopheles]

Aaaaaaaand it still does it, leaving the head gaskets as the cause. YAAAAAAAAAAAAAY! :smt102

[Okin DaVanh]

Yeah... Pretty much what I came to as my conclusion here in this 4 page thread:
viewtopic.php?f=11&t=23488 (https://sl-i.net/FORUM/viewtopic.php?f=11&t=23488)

[Thomistopheles]

Oh well. I was sort of expecting this since there was no record of a HG job...and I have records of all 68 oil changes, every tire rotation, brake jobs, T-belt, collision repair, suspension/steering work... everything.

I've got $1500 in the car including purchase price, blue book value is $2k+ more than that... so I'm alright with putting more time and money into it. Gaskets, T-belt, water pump, clutch, etc.

Besides, this will give me a chance to clean everything. Sandblast and powder coat brackets and the intake manifold, degrease the engine bay... all the fun stuff.

[StatGSR]

have you replaced the radiator cap?

[Thomistopheles]

Yep. The cap was the first thing I did.

[96LegacyWagon]

What are the signs of a bad radiator cap? I have been having a similar issue as well and I put the UV dye in the overflow tank, but it does not appear to have been sucked into the radiator at any point after adding it.