here is one to think about....

[jlk2.5gt]

So my car, a 97 legacy gt keeping having bubbles in the coolant overflow resivour only after I turn my vehicle off, after is has got to normal operating temp. there are no external coolant leaks, no coolant in the oil, no coolant in the trans fluid( i figured maybe it was leaking into the trans.cooler). the heater core is not leaking. just to make sure it was not the radiator cap, or thermostat i replaced them = no change. my radiator and heater hoses are new. the coolant is mixed properly and tests good, and is not discolored. The cooling fan is cycling properly, and I bled the cooling system correctly, and while it was warming up, (with the cap off to bleed air) you could see the water flowing in the radiator with means the water pump is working (and has been replaced a year ago or so. when the car cools down and i can open the cap, it is always a little low, but does not suck any out of the overflow tank. and i notice no white smoke at the tail pipe. if i drive the car for 45 min. at highway speed and come to a toll with some traffic back-up its starts to get hot, i slam my heat on for a sec. and the car cools down, anfd then i start to drive again at highway speed and it runs at normal temp. my radiator and condensor fins are straight and not plugged, or blocked.
1. where is the coolant going, if i cant find a leak?
2. where are the bubbles in the overflow tank coming from, and why none while the engine is running?

Tom. i will pressure test the cooling system, but any one with any input will be appreciated.
thanks

[PetterFan]

Normally, coolant bubbles mean head gasket problems, but that would be when the engine is running... :-?

[jlk2.5gt]

Its was my head gasket. it took a week to finally button up, but i removed the engine, replaced the head gaskets with the new updated one, re-sealed the plastic cover (on the rear of the block). there was absolutely no sludge at all when i removed my valve covers (subaru kicks ass).
All in all it was a pretty simple and easy job. I was even able to re-move and install the engine with no-one helping with the engine hoist. This engine design is one of the easiest engines to pull I have ever worked on.
The car runs great, and now is in perfect running conditon.

[blackgtbeauty]

for this reason;


This engine design is one of the easiest engines to pull I have ever worked on.

and the fact that soooo many parts are swappable among subie's, i like to refer to them as "life size legos".

and for this i'm thankful (wrx wheel, sti seats......).

[PetterFan]

I'm glad you fiqured that out, and now, you won't have to deal with it the HG for a long, long, long time! :smile:

[2.5GT]

Normally, coolant bubbles mean head gasket problems, but that would be when the engine is running... :-?

coolant in the resevior tank? or in the radiator? cuz mine's bubbling when the engine is warm up and shut off.

[PetterFan]

Normally, coolant bubbles mean head gasket problems, but that would be when the engine is running... :-?

coolant in the resevior tank? or in the radiator? cuz mine's bubbling when the engine is warm up and shut off.

In the radiator for sure, and Im pretty sure it will bubble in the resivore too.

[BAC5.2]

Coolant in the resivoir tank will bubble. It bubbles in the radiator because the thermostat is opening and closing and coolant is actually being pumped through the engine by the water pump.

What tends to happen with headgaskets, is it will fill the overflow bottle and drain out of the drain tube. When you shut the car off, the system will cool down and suck the coolant out of the overflow back into the system. Everything looks OK, but you lose coolant every time you run the car, and when you really get on it you start to overheat.

[2.5GT]

Some good info, i'll keep in mind.