So I have a 96 Impreza L 2.2 AWD that seems to only over heat when I go up I-90 at Snoqualmie pass. I snow board and used this car last year without any problems. But now it over heats. In the last month I've replaced the radiator, thermostat, water pump, timing belt, hoses, and headgaskets. And it still over heats when I go up the pass. I've raised the front.of the car when I refilled the coolant and filled by pouring directly into the upper rad hose and then let it burp with the cap off and the heat on. I'm out of ideas.. the thernostat is.in the correct upside down way, there is never any bubbles coming from the overflow tank or radiator while.its running... Any ideas?

OEM thermostat, or parts store? These engines really do not agree with anything other than OEM.

Are the radiator fans working as they should?

Guessing it's probably pretty cold. Try flushing the heater core it could be plugged. The heater core is part of the bypass system and routes hot coolant back side of the thermostat. In very cold weather it's just enough to keep the thermostat open when all of the coolant coming out of the radiator is below 170 degrees.

Did you use a Subaru t-stat or one from the parts store? Check that the fans come on and also check that you super burped the radiator.

A clogged heater core will make your car overheat on these cars, and also as mentioned before OEM or Exactfit t-stat is the way to go.

It's a genuine Subaru thermostat, and it was about 50degrees F outside when it over heated, if the heater core was blocked would it still blow out hot air? The fans are working correctly, i have burped it about ten times and no air comes out, but when its hot or over heating the upper hose is hot but when i squeeze it it feels like there is nothing in it... And then as it cools I.can hear and feel the hose sucking the coolant back in from the over flow tank also the bottom rad hose is sometimes cool to the touch when the upper is piping hot

50 degrees shouldn't be cold enough for that to happen but it's hard to say.

If the core is partially plugged you could still get heat, and not have enough flow for the coolant to keep it's temperature by the time it gets back out to the thermostat. 190 degree coolant in the core can still make plenty of hot air, but not be hot enough when it gets back to the engine to keep the thermostat (which opens at 170F degrees) open. The lack of flow could mean the coolant stays in the core just long enough to cool down below 170.

 

Did you ever replace the radiator cap?

What about the small rubber hose that attaches to the side of the water pump? (that is the bypass hose that brings coolant back to the thermostat).

I wonder if it's a factor outside of the cooling system? If it's running really lean, that would cause very high EGTs and possibly overheat?

 

Anyone?

If the thermostat is okay and it's not loosing coolant, and it overheats under load (higher speeds and long uphill climbs) I would suspect a partially clogged radiator. I don't suggest a backflush on the radiator since you can spend that $50 on a new radiator which is about $100.

 

Fans have nothing to do with it since you're travelling fast enough to get proper air flow through the radiator. Fan only comes into play if you are stopped for any length of time with the motor still running.

 

Sorry, just re-read your original post and you already replaced the radiator. Just a long shot since you've had quite a bit of work done on the car already. Check the air flow with the fan(s) running. If your mechanic inadvertantly reversed the wiring on the fan and the fans push air forward (against the direction of travel), then this would give you those symptoms. The car starts to overheat, fan comes on to get more air flow through the radiator but instead it pushes air forward causing worse air flow through the radiator causing more overheating. Unusual, but I've seen it happen.

 

If you want a very experienced Subaru mechanic to troubleshoot/fix this problem, drop me a PM with your number or email and I'll pass along that information. He's located in Snohomish which isn't too far from Seattle and he's well below the cost of a dealer or any quality independant I've seen.

Edited January 9, 201214 yr by edrach

I wouldn't buy another radiator till I checked the coolant with a test from the parts store for bad HG.

radiator has been done.

 

In the last month I've replaced the

 

radiator,

thermostat,

water pump,

timing belt,

hoses, and

headgaskets.

 

And it still over heats when I go up the pass. I've raised the front.of the car when I refilled the coolant and filled by pouring directly into the upper rad hose and then let it burp with the cap off and the heat on. I'm out of ideas.. the thernostat is.in the correct upside down way,

Sounds like HG's to me. Cold bottom hose while the top is hot indicates the water pump is cavitating.

 

You may have just done them - but did you have the heads surfaced or checked for cracks? HG replacement takes patience and attention to detail and can easily go sideways if you don't know what you are doing.

 

GD