Trying to overheat

So my Outback temp gauge just shot to the top yesterday for no reason and before I could even pull over it dropped back down to normal. It did it again a little later.
Sounds to me like a thermostat trying to fail?
Car still runs the same with other issues.

Any other opinions?

 

Either that or an air pocket in the coolant. Try bleeding the system.

 

sounds about right

 

Thermostat is on the bottom right? I think I will go ahead and replace it just to make sure. New Thermostat and flush the system will at least help narrow it down if it does it again.
I can't make the car do it so I might as well start eliminating things.

 

The thermostat is good place to start. The stocker fails closed which is crazy. I hvae the crucial 160 degree that will fail open. Much safer to run too cool if it fails instead of too hot.

 

Hmmm. Replaced thermostat. Car wouldn't even get past warm sitting in the driveway afterward. As soon as I drive 3 miles, bam. Overheating. Coolant was bubbling in the overflow jug. Top hose was burning hot. It's not drinking coolant or smoking like a head gasket? How do the water pumps fail on these 2.5?

 

sounds like you have air in the system

 

I had a vw GTI that the water pump would fail at rpm's higher than 3500. What would happen is the flapper on the water pump shaft got a crack in it and when it would turn at idle it would have enough friction to move the flapper to pump the water. At higher rpm it would slip causing an overheat. My $0.02

 

So how do I burp the air out?

 

Take the cap off and let sit overnight, top it off and try again

fill slow engine off, squeeze hoses and fill, start with cap off, get to operating temp and fill as needed.

 

When the water pump fails it seizes up and the timing belt melts and then really bad things happen.

I bet its just air at this point. A couple of heating and cooling cycles with topping it off in between should fix the problem.

 

I have always had good luck with putting it on ramps while filling by Breels method.

 

depending on the car it can take about 30 minutes at idle before all the air works it way out. With a little effort you can pull driver side of the cam covers off and look at the belt and tensioner for excessive wear

 

Well. I spent quite a bit of time filling and squeezing the pipes last night. I left the cap off all night last night so I will try to top it off this morning before I drive to work and see what happens.

 

Well, made is my 15 mile drive today with no issues. I have done cooling system work on a lot of cars but I have never had these issues with "burping" the system before. Is this a unique thing to boxer engines or something?

Thanks for everyone's help. I love this place!

 

Nah, all cars should be properly burped. I have always done it with the front elevated and that has never failed me.