I'm wondering if anyone can explain the situation that occurred in my 97 outback, 2.5l. I was heading home from the coast when my car suddenly began to overheat. I pulled off at the nearest service station and noticed that my overflow reservoir was full. After letting the engine cool it didn't suck the coolant back into the radiator so I opened the radiator cap and released the pressure. I then filled the radiator with water. Naturally the temp dropped and I headed off, but it went right back to overheating. I pulled off again and let it cool then drained the radiator by taking the hose off the bottom, not much fluid came out. I reattached everything and filled it with new coolant. This fixed the problem and I have not had a problem since. I'm assuming there was an air pocket in there somewhere. I need to know if I should have the cooling system checked out, or if the head gasket might be leaking, or whatever else I should look into. Is it likely that my problem will reoccur?

May be the HG. Is there any oil film in the overflow tank? If so its a HG. Had you opened the collant system prior to the overheat? Some how the air got in the system. If it wasn't from maintenance, it was from a leaking HG, IMHO.

It didn't look like there was any signs of oil in the overflow...and I hadn't touched the cooling system at all prior to the overheat, I'm not sure how the air got in there?

Fill up the radiator slowly and then top off the overflow tank at the proper level.

 

Give the car another shot and see if it still misbehaves when you have the correct amount of coolant in the system?

 

I had a similar issue and it looks as though I was low on coolant and had a bubble in the system.

 

I filled it properly and now, mine appears to be happy.