Very odd cooling problem

[unsullied_spy]

My 04 Legacy is overheating when the engine is warmed up and idling (coasting or stopped at a light) but if you wind up the engine to 4k or so the temperatures drop right away. Near as I can tell from my IR temp gauge (not 100% accurate) it's running perfect temps. I get 175-185 at the crossover pipe right before the upper radiator hose and about 180-185 at the cylinder heads. It has 87k miles on the clock with new water pump and hoses at 72k, HGs and all other gaskets changed at 74k, new cooling fan at 75k, new thermostat at 85k, new thermostat 2 weeks ago, new radiator last week, and a new coolant temperature sensor a couple days ago. After taking the following video my upper radiator hose measured about 140 but the lower was 80. The heater core inlet was around 180 and the outlet around 170. I am completely lost at this point as far as why my gauge pegs out whenever the engine idles for more than 30 seconds.

The temp I got in the video was off of the crossover pipe. Any guesses as to what the squeaking noise is are appreciated as well. My best guess is the tensioner pulley for the A/C but I haven't really looked into it yet.

http://i140.photobucket.com/albums/r37/Unsullied_Spy/th_M4H03347.jpg (http://s140.photobucket.com/albums/r37/Unsullied_Spy/?action=view&current=M4H03347.mp4)

[harrymaneuvers]

Did you use an OEM thermostat?

[unsullied_spy]

OEM thermostat and temperature sensor

[unsullied_spy]

Also seems to indicate that it's overheating once the engine has been running and up to temperature for a while and the RPMs drop below 3,000. It climbed up again on my way home today after running some errands after work so I pulled over and the upper radiator hose was only 170, cylinder heads were around 180. I highly doubt it's anything related to the water pump, thermostat, or radiator.

[harrymaneuvers]

If your RPM's need to stay above 3,000 in order to keep cool than that tells me that your cooling system is not moving the coolant fast enough at idle.


If you were to let the car warm up and then drive around and come to a stop... it sounds like the car would start to overheat. Can you then just put the car in neutral and rev up to 3,000 RPM (while not moving) and watch the temps drop back down to normal?

If so, then I can only imagine that it is a waterpump issue. If the temps dont come back down while stopped and reving to 3,000 RPM, then I think it could also be a fan relay or something else not causing your fans to start.

[unsullied_spy]

If your RPM's need to stay above 3,000 in order to keep cool than that tells me that your cooling system is not moving the coolant fast enough at idle.


If you were to let the car warm up and then drive around and come to a stop... it sounds like the car would start to overheat. Can you then just put the car in neutral and rev up to 3,000 RPM (while not moving) and watch the temps drop back down to normal?

If so, then I can only imagine that it is a waterpump issue. If the temps dont come back down while stopped and reving to 3,000 RPM, then I think it could also be a fan relay or something else not causing your fans to start.
That is correct, it will overheat at idle and cool when revved. Is there a way to test the water pump or does it just need replaced? It's just over a year old and I bought a Paraut (supposed to be very good quality) so I'm hoping it's not the pump...let alone trying to swap water pumps when it's 10 degrees out. The fans are both coming on and blowing, and the main fan has been replaced once.

[unsullied_spy]

Got a chance to track down my coolant leak today, looks like it's coming from the thermostat housing. The car overheated a few months back, perhaps the housing warped a little bit causing it to leak and perhaps introduce a little bit of air into the system? I'm going to try to get into a Subaru mechanic on Wednesday and see if they can come up with anything. Don't have the money to leave it for a proper repair but hopefully get an assesment.