Sorry to say, but you probably have a blown head gasket. My brother just had this same thing happen to his Sooby over the weekend and that's what they told him. Do a Google search on "Subaru Head Gasket Problems" and you'll see what I'm talking about.
Go here and see what others are saying.
http://www.subaruoutback.org/forums/showthread.php?s=2544e0e3856e48143872a5bbf6808fb4&threadid=16064&highlight=head+gasket
Hi! I have some info that might help you also. First, did the car run cool and fine before you changed the pump and thermostat? If so, you may only need a thermostat. I changed my pump and thermostat on my 95 2.2L, replaced the thermostat with a cheap one from NAPA, and ran it. My motor ran hot, my radiator fans ran constantly, and my temperature guage jumped up and down, never getting cooler than half way. I pulled out the NAPA thermostat, bought a factory thermostat from a Subaru dealer, and put it back in. It cured all of my overheating problems, my fans hardly ever run, and my temp guage stays at about 3/8 into the normal. It seems like some things on these cars you MUST replace with factory parts, or it will NOT run right! My thermostat costed about $22.00, pretty cheap fix if this is your problem! Hope it helps!
You may need to replace the radiator thermostat and gasket.
You need to burp the radiator and cooling system.
You could have a bad thermostat, just because its new doesn't mean its good, TRUST ME ON THAT, or you could possible have an air pocket in the cooling system.
One reasons a Subaru Forester may overheat is because the radiator may need replaced. Another reason could be the thermostat.
Subaru 2.5 thermostat's are bass ackwards...follow the lower radiator hose to the block...there ya go...
In a 2004 Subaru Outback, the thermostat is located on the bottom of the engine on the driver's side. Remove the screws holding the fitting that the hose (from the bottom of the radiator leading to the engine block) is attached to, remove the fitting, and the thermostat will be underneath.
place the thermostat with the pointed facing out-ward away for the motor.
Under the engine where the lower radiator hose connects.
inside the thermostat housing where the lower radiator hose connects to the engine block.
Go to subaruoutback.org Subaru Outback > General > Do-It-Yourself Illustrated Guide > Replacing lights on the instrument cluster. Good luck...
I have a 2002 Subaru Impreza Outback and it have the thermostat on the right bellow the engine. You can fallow the hose from the radiator that goes to the bottom of the engine.
EVERY 50,000 KMS.