Obviously. I was confirming that the coolant levels are fine. The water pump will be replaced.
Why does a cooling system with good coolant levels overheat? A leaking pump still provides flow. Does a tiny leak lower the system pressure? From 15psi to 12 psi to 2 psi?
Is it airflow? Engine load? Air temp? Life?
While the engine is cold, remove the radiator cap and start the car. If coolant gushes out of the radiator, you have a head gasket problem. If it’s a little problem, you might get a small geyser, and you should get a pal to start the car while you inspect.
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When I remove the radiator cap water immediately flows into the reservoir tank. Is this what you mean? If so, I will take it to a shop to replace the head gasket and water pump. Thank you!
No. I mean out of the cap orifice and onto the top of the radiator.
I’d find a good Subaru shop and have them diagnose it. My bet is on head gaskets.
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Don’t just tell a shop to do something that may not be needed. Find a Subaru shop , pay the diagnostic fee so you will fix what is really wrong.
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Your engine has two head gaskets, so make sure that they are both replaced… if a bad head gasket is indeed the source of the problem. Also, insist on the installation of Subaru’s updated head gasket design, along with Subaru’s cooling system additive.
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-from a friends legacy-on a legacy forum
It seems a bit premature to blame head gaskets at this point. You say the thermostat is working fine. Based on what?
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Oh, I didn’t know that was possible. Thanks for sharing. In my case it goes up to the red (left of H") and then back down to normal (mid) repeatedly.
I tested the thermostat in boiling water to confirm that it was opening all the way and closing.
I agree, but a lot of people seem to think it’s the head gasket, and I’ve read that’s something that needs to be replaced immediately when damaged.
I feel like the car will be damaged further before I figure it out myself, so I will schedule someone to look at it.
By the way, after testing the thermostat I figured I’d buy a new one just in case. They are inexpensive and I don’t know how old mine is. I’ll put it in tomorrow morning.
Just make sure it’s a Subaru shop, they have lots of quirks.
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Nether did anyone else on the forum
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Just a note on testing the thermostat. When you put it in water, put a candy thermometer in there too to note at what temp it opens and what temp it closes again. They can open way too late but I’ve only had one bad one. Cheap? I think my last one was $25.
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If you have any leaks in the cooling system (e.g. the water pump weep hole), you should repair those first before presuming the problem lies elsewhere. Leaks create air pockets in the coolant, and even small air pockets can cause this symptom. While repairing all the leaks common sense says to replace the thermostat and the radiator cap at the same time, if they haven’t been replaced in the past 2-3 years already. There’s a downside to replacing stuff that may be working ok, as the new part may fail. But its pretty easy to check a new thermostat in a pot of hot water to make sure it opens at the correct temperature and the correct dimension, and brand-name radiator caps are rare failure items as replacement parts.
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Replacing the water pump requires replacing the timing belt. I wouldn’t go to that expense until I had determined whether the head gaskets are bad.
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All of the replies have merit. Have also seen wide variations in indicated temperature (on a BMW) due to an electrical issue affecting the gauge. While this probably is a rare problem, you can try using a non-contacting infrared thermometer to check temperatures independently.
Check first for air in the system, that’s easiest to fix. Another indicator of air is poor heater operation. An owner can look for signs of water in the oil (head gasket leak) and perform a cooling system leak down test (a head gasket leak as well as other things can cause this). You can have exhaust and open radiator sniffed (with electronic tools) for exhaust gases, also indicating a head gasket leak. Anything with the head gasket needs to be fixed asap before incurring major damage.
What’s the point of sniffing for exhaust gasses in the exhaust? You know there will be exhaust gasses there. Just asking.
Sniffing for exhaust gasses at the radiator.