My 1992 Legacy 2.2litre always acts like it's overheating. At idle, the temp stays right at the middle, but once I start driving, the temp shoots up to the red. I open the radiator cap and stick my finger in there and it's not even luke warm...

 

what the heck? I dont have a book but is there a temp sensor that could be out?

First off I'd suggest bleeding the air out the cooling system. If there are any air bubbles it can cause weird sensor readings, and if there's a bubble at the tstat, it won't open, thereby causing the radiator to not flow coolant while your motor overheats!

My 1992 Legacy 2.2litre always acts like it's overheating. At idle, the temp stays right at the middle, but once I start driving, the temp shoots up to the red. I open the radiator cap and stick my finger in there and it's not even luke warm...

 

what the heck? I dont have a book but is there a temp sensor that could be out?

 

Take out the thermostat and toss it in a pot of boiling water to make sure its opening up. Sounds like its sticking and not flowing coolant to the radiator.

replace thermostat like he said, don't run it hot and let us know what happens.

while the hoses are disconnected for the thermostat install you can run water through the radiator to make sure it's not clogged as well. once you're done diagnosing, drain and refill the radiator with distilled water and antifreeze before hooking the hoses back up. no need for tap water in the system, you want distilled.

First off I'd suggest bleeding the air out the cooling system. If there are any air bubbles it can cause weird sensor readings, and if there's a bubble at the tstat, it won't open, thereby causing the radiator to not flow coolant while your motor overheats!

 

i've tried letting it run and run wit the cap off to let out the air.. doesn't seem to make a diff.. is there another way?

Take out the thermostat and toss it in a pot of boiling water to make sure its opening up. Sounds like its sticking and not flowing coolant to the radiator.

 

replaced the thermostat- same results..

i've tried letting it run and run wit the cap off to let out the air.. doesn't seem to make a diff.. is there another way?

 

People put the car up on ramps and let it run. Do you get good heat also?

a cold radiator at the top indicates no flow. If the bottom hose is hot, and the upper hose is cold, your radiator is clogged. If both are the same, it cna be an air bubble or a eroded water pump impeller.

 

nipper

i've tried letting it run and run wit the cap off to let out the air.. doesn't seem to make a diff.. is there another way?

 

Best way in my experience is to start the car with the cap off and let it run until the temp gauge starts going up. Then turn on the heater full blast. This will ensure flow of coolant thru the heater core. It will take a while for the tstat to open since you're sucking heat out and only idling, but don't get anxious and jump on the throttle. Just let the stat open up, and once your radiator gets hot let it idle for another ~5 minutes or so. You'll lose some coolant in this process. Just make sure your overflow is at the correct level. Once it's hot, throw the cap back on, and take it for a drive. Check your overflow level after your drive and again after the system cools down.

 

You should have a bleeder screw somewhere, possibly near the top rad. hose. I'd unscrew that while it's warming up as it helps get air out of the system.

 

EDIT: I also squeeze and tap the top/bottom hoses while it's warming up, this helps to get any air bubbles stuck in there out.

There's a bleed screw on the passenger side of the radiator. This MUST be removed in order to get all the air out.

 

Also, if you are using anything but an OEM thermostat, replace it with an OEM subaru thermostat.