[JW657]

Just flushed the hell out of the system. Fired up the car and let it warm up. Before it was even mid-temp range the reservoir started filling up and boiling out. I still don't see any issues with the water pump.

I guess it's probably the head gasket? Dammit. That sounds like a huge job...

If there's exhaust getting into the cooling system, it would be pretty noticeable on a cold start. If you start the engine and hard rev it for a few seconds, then check the coolant cap and it blows off on a cold engine, then there's likely a problem with your head gaskets (well, not every time). If you left the cap off while the engine was idling and warming up, maybe it boiled from the fact that it had no pressure? Exhaust gas doesn't make it boil necessarily, it makes it puke out because of the gases pushing it out of the cap, that's why it will do it cold. If the engine was overheating from a bad head gasket, you would probably know pretty quick just from driving it around.

Is it possible that you just had a bubble push itself out?

 

[Chingon]

Just to clarify, it didn't actually "boil." It just slowly and steadily filled up the reservoir and starting overflowing out the cap. I suppose it could've been a huge air bubble. I'll let it sit overnight, then start it up and rev it to see what happens.

I'm just wondering if I'm up for a head gasket replacement...

 

[JW657]

Just to clarify, it didn't actually "boil." It just slowly and steadily filled up the reservoir and starting overflowing out the cap. I suppose it could've been a huge air bubble. I'll let it sit overnight, then start it up and rev it to see what happens.

I'm just wondering if I'm up for a head gasket replacement...

I wouldn't worry too much. Start it in the morning and see if it builds pressure cold, if it doesn't take it for a drive and see if it acts funny. Blown headgaskets tend to show pretty easily. Any check engine lights? If the exhaust gases were getting into the cooling system, you would think there would be a compression issue on one of the cylinders.

If you haven't overheated it or anything, you are probably fine. (hopefully) :lol2: