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Overheating after installing new thermostat


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I drive a 2001 Subaru Legacy, 2.5L 4V engine with automatic transmission.

Over the weekend I changed out my valve cover gaskets, spark plugs, water pump, and thermostat. Once I got the engine put back together I took my car for a test drive and found that it was overheating. I figured there might be air trapped in my cooling system so I ran the engine a few times with the radiator cap off to see if any air bubbled out. After doing this the engine still overheated when I ran it so I'm thinking there might be a different issue.

I also noticed that I have water pooling under my passenger side wheel well. I'm not sure if this is related.

Any ideas, comments, assistance are appreciated. I'm hoping to get my car back on the road soon.

Thanks!

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Are your radiator fans coming on when the temp gauge gets into the middle range?

 

Did you use the OEM Subaru thermostat? When the car is hot, are both top and bottom radiator hoses hot to touch?

 

When you say water is coming out, you mean coolant is coming out of the radiator overflow tank? Did you add coolant up to the full line in the overflow tank?

 

Tell us a bit more about the overheating behavior. Is this only when the car is climbing hills and working hard, or when the car is idling in traffic? Does the temp gauge come back down or just stay high once hot?

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Radiator fans are coming on. I did not get a thermostat from Subaru, that might be the issue. Top hose is hot, I'll check top and bottom hoses when I look at it again tonight. Yep, overflow tank is full, that does not appear to be leaking. I have no idea where the water is coming from, it's pooling on the opposite side from the overflow tank. I use 50/50 coolant/antifreeze and not water anyway. When the car is idling, it won't overheat but the needle hangs out pretty close to the top white line on my thermostat gauge. When I drive or rev the engine it'll push the engine into overheating. Temp gauge doesn't come down unless I turn the heat on in the car.
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Your symptoms sound like a thermostat problem is likely. Aftermarket thermostats tend to have issues, once you get a look at the Subaru OEM you will see the difference. It is much larger, heavier, flows better and opens at the correct temperature.

 

Your symptoms don't match air bubbles trapped in the block. These tend to cause transient overheating. The temp gauge comes down on its own when driving around.

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I tried to use a motorad thermostat once and it was a big mistake. I ended up using a gates that clearly stated “OE exact” on the listing. It was like $12 and it is identical to the OEM one. Also there is a drain tube on the passenger side of the car. That could be where your water is coming from, mine does it all the time.

 

 

Sent from my iPhone using Tapatalk

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Thanks everyone!

The issue ended up being a rookie mistake (this is my first time doing this fix). I put the thermostat in the wrong direction. Pulled it out and put it in the right way. I didn't have time to run the engine to see if it was still overheating but I'm pretty sure that was the issue. Live and learn..

Re: water draining: that makes sense that it's coming out of the drain tube, the water is pooling under the passenger side. I'm guessing it's not worth being too concerned about.

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A Subaru Tstat or the Stant 48457 which are made the same would have prevented this issue.

You can't install those backwards as the long pellet side wouldn't let you mount the cover.

 

O.

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