Weird car overheating question

Hmmmm, yes. I added just under a liter of water/antifreeeze. I have not noticed any leaks, but I will get it tested this afternoon while at the shop.

:smack: I have only worked on vehicles with surge tanks for so damn long I keep forgetting this.

Which leads us to a teaching moment:

Overflow jars (also called coolant reservoirs) are NOT within the pressurized cooling system. The pressure cap is usually on the radiator, sometimes elsewhere on the engine, but a small hose leads from the cap area to the jar. The jar has a dust cap and a vent to the atmosphere.

Surge tanks (also called reservoirs, and quite unfortunately, overflow jars) ARE within the pressurized system. In most designs, the pressure cap is on the surge tank itself. It’s essentially an extension of the radiator.

Both overflow jars and surge tanks are usually made out of translucent plastic (which becomes nearly opaque with age). Most parts and service personnel do not choose their words carefully to describe them, often calling both “reservoirs” or “jars.” So naturally the distinction can be confusing to the layman. The point to know is, if you have a surge tank, the liquid level in it is a reliable indicator of the level of coolant in the system. If you have an overflow jar, it is not, and you need to look into the radiator to be CERTAIN of the coolant level.

No problem! (still, a liter doesn’t seem like much to me, you may still have an issue here)

Soon, my friend.

Please take your Forester to the dealer. I know its expensive, but being a member of a couple of subaru forums this seems to be the best course of action. 2000-2005?(I know they solved it by 2006, which is what I have) models tended to have weak headgaskets, and SOA (subaru of america) has released bulletins about this. Depending on your mileage you might be able to get them to do the work for you.

I am really hesitant about taking any subaru to a non subaru mechanic (there are non-dealer mechanics that only work on these cars, they would be good too, the specialization factor is what I aim for).

The way these leak is youll see coolant disapearing, but oil might not be getting into the coolant, or coolant into the oil. Being a boxer engine the headgasket can blow in such a way that the coolant only goes into the cylinder, or will drain into the oil return passages (not under pressure, so no oil gets into the coolant).

I seem to remember the dealers charge about $1200 to do a headgasket change, and I think it is worth the money to have done properly, especially since once done the car will last at least that many more miles (my last subaru had 220k).

One way to find a good dealer is ask anyone you see with a subaru in your area what dealer they like.

So I was explaining my difficulties to our maintenance guy and he said “Have you checked your radiator cap?”

I replied with a “Huh?”

We went out to the car, he took off the radiator cap and said “Look at this, your discy thing is completely stuck to the rubbery thing!” (he used different words).

He unstuck it, cleaned it up, and said “This is what lets coolant back in from the overflow tank, your radiator was trying to draw coolant back in and it couldn’t, so it drew air in from somewhere else”

So it sounds like I might have a small leak somewhere, does this logic make sense to the rest of you?

Yes, the radiator caps go bad too (duh, forgot to mention this). Though go get a new one from the dealer.

P.S. I don work for a SOA dealer, I just know there are certain things I only get for cars from the dealer.

Oops, Cross-posted with you LikeFry. I did a lot of reading last night, and the headgasket problem was with the Phase 1 engines, which was through 2001. My 2003 shouldn’t have that same weakness.

But I am still taking it to have the coolant tested for CO, and it is being done at the dealership. Thanks for the advice!

Oops, guess I got the years wrong. Also, I didnt ask, does yours have the turbo motor? On hot days that can sometimes cause a surge of temperature if you get on it.

Ill keep my fingers crossed that your radiator cap was the issue, and that you can look forward to many more years and 100’s of thousands of miles out of your car, I know I am hoping the same for mine.


Nope, no turbo on ol’ Bess.

Thanks for the good wishes, I’m hoping to put 250K on this one. Here’s to good luck with your Scoobaru, too!