My 2002 Subaru outback is running hot ...I took it out on the highway with the heat off and after 5 mins. the needle went to hot ....I put the heat on high to bring the needle down and had cold air coming out...Then after shutting car down for a few minutes and starting it up again, I had heat...Could my. Therosate be sticking?????

Low coolant level, improper filling procedure, Thermostat unable to open without being immersed on the engine side. They bleed subarus as a last step at the cooling system bleed screw before returning them to service. The complete filling procedure must be observed any time it goes low. A leaking water pump is best replaced with a Subaru genuine part during the timing belt replacement. A system pressure test for leak diagnosis is best.

Head gasket leakage to the outside underneath can often be found during an engine running inspection at operating temp, after filling procedure is complete. A Subaru specialist can provide the updated parts and procedures you cannot find in a book.

Don't understand what your trying to say...

Check to see if there is anything leaking .

I can't tell when I'm driving but when. It's running in one spot I do see wet where the bottom radiator hose is but that could be from the over flow when it went over

I would try some of the dye kits that you can buy makes it easy to find the leak in either the engine ( Oil leak) the coolent system or the transmission system , I have use one for my Outback the the dye makes the leaks really stand out and you can also use it with the pressure testing

Thanks but I gave up and took it to my mechanic....I drove there this morning a good 15 mins on the highway with heat on high and it never ran hot!!! It lost heat for about 6 seconds then heat returned

Let us know what your mechanic found " we are All in thisTogether "

I will, thanks again

Your answers were in the first 2 entries. have your mechanic read it and explain it. A subaru specialist can provide the parts and corrections arrived at by them through trial and error in the aftermarket. The design of the system requires the procedures be followed or you may be unable to get it full. after sitting long enough with engine off you could accidentally experience the thermostat opening from a heat soak. sometimes 40 minutes is enough if you choose to sidestep the service manual procedure. It would still require adding to the system and bleeding the air. that explains your interruptions in heat output. and cooler reading on the indicator.

Oh, since you have overheated it a few times, it was low, and you arent understanding, the basic idea is get it full . The coolant cannot enter the engine unless the thermostat is open. the thermostat cannot open unless it is immersed, savvy ? that means fill the block thru the upper hose with it disconnected and turned to accept a funnel. Aufweidersein, or whatever.