Its getting HOT in here....

Greetings everyone. Have a quick question. My 05 Subaru Legacy GT is running hot from time to time. Never into the red, but dangerously close. I've noticed that it doesn't more frequently when the air conditioner is on, but that's not always the case. I replace a thermostat and flush the cooling system out.... and yes I removed all the air that I could out of the radiator system. Any other ideas on how this overheating event might be happening?

 

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What is the current coolant level in the overflow tank, when the car is cold ?

 

Are both fan's working ?

Has the radiator ever been replaced? How many miles on the car/rad?

 

Is it worse when the weather is warmer, going uphill or when the A/C is on? Does the temp go down if you turn the heater on full blast?

 

Radiators are a wear item, especially in subarus, the cross tubes get build up on the inside, sometimes to point of completely clogging. I had to replace the rad in my spec B at about 250K, even with occasional flushing and always running clean quality coolant they have a lifetime. Mine was around 50% plugged by the time I pulled it, only passing coolant through a few tubes at the top and bottom, the center was stone cold after running the car. I have seen the same issue on most of the (high mileage) Subarus I've owned.

 

Gary

https://legacygt.com/forums/showthread.php/idea-web-links-saved-various-parts-219238p9.html

 

See post # 327.

 

I thought I heard something like this recently...

What is the current coolant level in the overflow tank, when the car is cold ?

 

Are both fan's working ?

Hey there. Current cooling level with the engine cold is in between the min in the max in the reservoir tank. I haven't had to add any more coolant to it after I flushed it and replace the thermostat. And yes, both fans are working, however, they don't both always run. One of them will run when the car is this that normal operating temperature, then when the AC cuts on, they both turn on pretty high. I think they're cycling on as required. What is the fan speed procedure the verify they are running properly?

 

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Has the radiator ever been replaced? How many miles on the car/rad?

 

Is it worse when the weather is warmer, going uphill or when the A/C is on? Does the temp go down if you turn the heater on full blast?

 

Radiators are a wear item, especially in subarus, the cross tubes get build up on the inside, sometimes to point of completely clogging. I had to replace the rad in my spec B at about 250K, even with occasional flushing and always running clean quality coolant they have a lifetime. Mine was around 50% plugged by the time I pulled it, only passing coolant through a few tubes at the top and bottom, the center was stone cold after running the car. I have seen the same issue on most of the (high mileage) Subarus I've owned.

 

Gary

Hey Gary. Thanks for the feedback. It's very sporadic. It doesn't always do it when the AC is on, and it doesn't always do it with the engine under heavy load. It's kind of Hit and Miss really. I have not been able to correlate engine speed or air-conditioning functionality to the overheating issue. The car has 210000 miles on it now and it's probably the original radiator. You're probably right. I believe the radiator may need to be replaced. I just wasn't sure if there was another temperature module or relay or something that might need to be checked before replacing the radiator

 

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Ever mix coolant colors like green with blue?

Run the car until it’s fully up to temp, let the fans cycle on and off a few time to be sure. Shut it OFf, then try and reach through the fans and feel the face of the radiator from top to bottom, if there are any cold sections it’s time to replace it.

 

If it’s sporadic and not related to heat load it could be something else. Some cars benefit from being nose up (ramps or jack stands) while burping air from the system. Though I find that turbo cars with the high mounted tank don’t really need this. Has the water pump been replaced (hopefully when the timing belt was done)?

Run the car until it’s fully up to temp, let the fans cycle on and off a few time to be sure. Shut it OFf, then try and reach through the fans and feel the face of the radiator from top to bottom, if there are any cold sections it’s time to replace it.

 

If it’s sporadic and not related to heat load it could be something else. Some cars benefit from being nose up (ramps or jack stands) while burping air from the system. Though I find that turbo cars with the high mounted tank don’t really need this. Has the water pump been replaced (hopefully when the timing belt was done)?

It was, in fact, the radiator. The car has 210000 miles on it now and that was the original radiator. Best of my knowledge anyhow. I'd say that's pretty good. Thanks for the Pearls of Wisdom

 

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