Overheating/burping

[Shetara]

I have a 2004 Subaru Outback Wagon. 180,000 miles.Head gaskets were replaced about 3 years ago. Due to overheating issues, just had a new radiator and themostat put in. It ran fine for a couple weeks, just in town driving. After driving up to the mountain, it stated overheating again. No signs of head gasket issues (no whit smoke, no smell, nothing leaking, no milky film on the oil cap)...my mechanic said there was probably air in the cooling system. Possibly coming from the head gaskets? Did some research and burped it a few days ago. Ran ok for a couple days then started to over heat. (Maybe I didn't burp it long enough?) Here's the catch. Before (and since I burped it) I've been driving around with the heat on (no fan) with a meat thermometer in the vent. When it was driving fine, the meat thermometer would read 160-170° and the car's thermometer would be mid way- where it mormally is. Now when the car's thermometer says its overheating, the thermometer in the vent shows normal temperature. What gives?! I am currently re-burping and air is coming out. I read that burping could take 2 hours. Could it take more?

[DaveT]

The signs of headgasket yout listed above are typical of badly failed headgaskets, not the beginning failure that causes air to continually get injected into the cooling system. The rate can be anything from it takes a week to notice a level change, to can't go 3 miles without pushing coolant out of the overflow.

Checking for air in the top hose by sharply squeezing - listen for giggle pin and air gurgles - and the level in the recovery tank. Do this before every drive. If everything is ok, there will be less air each time. If not, something is wrong and needs monitoring and more details to fiagnose.

[idosubaru]

Headgaskets.  What you're seeing it totally normal - particlarly for previously replaced gaskets. More than likely: 
a.  the heads weren't resurfaced

or

b. OEM Subaru or Fel Pro headgaskets were not used

 

Resurface the heads and use Turbo EJ25 headgaskets.  Gloyale and GD are both subaru speciliasts in Oregon that will repair it properly.  I forget the name of their shops - Superior Import or Superior Subaru for one them...

 

 

These dont fail by showing coolant/oil mixing or coolant in exhaust or compressiong tests - those are meaningless data points on these engines.  Or if they do fail that badly - it'll be blatantly obvious and probably not worth keeping the engine. 

[AdventureSubaru]

Sounds like the start of a repeat head gasket failure alright. As mentioned, if you take it to one of those guys, they'll make sure it's done right.

 

You can probably limp it along a little while by adding coolant/burping air regularly, but don't let it run hot or you can add to your problems. Head gaskets done right will last the lift of the car now. Especially if the turbo gaskets are used.

[Caboobaroo]

I wish people would QUIT RECOMMENDING FEL PRO HEAD GASKETS IN THE 2.5! They are junk and will continually blow because they are of subpar quality.