[outback1955]

I have a 1999 Outback, 2.5L EJ25 boxer. Starting to overheat on occasion. Original owner said gaskets were replaced at 80k miles, now has 188k. Engine will heat up (after driving for a while) but temp gauge will not always stay up, sometimes it will come back down after a minute or less. New water pump, flushed system, burped, 50/50 coolant. Replaced thermostat with an OEM and not a Subaru. What do you think?

Thanks guys!

 

[4wheeldog]

With the engine warmed up to operating temperature, and running, do you get bubbles in the overflow bottle? If you do, it is most likely head gasket(s).

You could also have someone do a cooling system pressure test. (Radiator cap replaced temporarily with a pump device with a gauge......Pressure is applied to the system cold, and any loss of pressure indicates a leak. Often, if the leak is external, you can find it this way. If it is internal, coolant is forced into the cylinders, or the crankcase.)

Good luck.

 

[RobLog]

Replaced thermostat with an OEM and not a Subaru.

This statement is confusing to me. If the thermostat is not a Subaru one then it is not OEM, just OEM "style", which is not the same thing. Aftermarket ones have frequently proven to be troublesome in our cars. Bottom line: you need a genuine Subaru thermostat in our cars or you will likely continue to have problems to matter what else you do.

 

[upflying]

This checks for combustion gases in the coolant.

 

[idosubaru]

When has the coolant last been messed with, drained, etc? It could simply have air bubbles in it. Those engines are notoriously difficult to bleed air from. Some have a plastic phillips head bleeder screw on top passengers side of radiator.

Or clogged radiator or fans not coming on...there's quite a few things to check.

Next time it's hotter than it should be:
1. do the fans come on
2. does cabin blow hot...then get cold after a minute or few?
3. any correlation to daytime temperatures, idling verses highway, etc?
4. are the radiator hoses hot (be careful!)?
5. do you have bubbles in the overflow.