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Subaru still overheats after repairs - worth more work?

Hello everybody!

I have some trouble with my beloved 2006 Subaru Forester and hope you can help me make a smart decision:
Two months ago, out of nowhere, the car started overheating. (Maybe not completely out of nowhere, because my father came to visit me and decided the car needed more coolant and filled the whole overflow tank. But we think this is not causality, but just coincidence.)
While I am new to Subarus, I am great at googling, and self-diagnosed it would be either (and hopefully) the thermostat, or a blown head gasket, apperently a common breaking point.

The very friendly and well-reviewed mechanic had a good look at it and told me the radiator was leaking, and if I wanted to fix it, it would be sensible to also replace the thermostat and timing belt.
Asked whether it was worth it he kept the car for another three days to give it a thorough assessment and told me afterwards, yes, the car is in a really good condition, go for it. 900$ seemed to be a fair price.

The first few days on short trips the Subaru did not overheat. I was so happy. I was so glad to take it for a long drive. Unfortunately, after two hours of driving in the summer heat with some stop-and-go-traffic, all of a sudden the temperature display went from constantly in the middle to top-of-red.
I got it back home and back to the mechanic. That was three weeks ago.
The news today was: he exchanged the (new) thermostat again, he tried engine sealant, he tried another engine sealant, nothing works. He says it’s probably the head gasket and will come back to me tomorrow with an estimate.

Now, dear car talk community who has to bravely read my post this far, my questions:

  1. Can he be sure it is the head gasket now?
  2. Is it common that a mechanic first repairs the radiator and thermostat (and timing belt) before realising the car’s problem is its head gasket?
  3. Assuming it was the head gasket from the start (because what are the odds it blows right after the radiater has been repaired, right?), is it just bad luck I paid the 900$ for the other repairs or can I claim some kind of warranty?
  4. The car is not worth much ( says about 3000$ in the current condition, which I don’t quite believe), but I have invested so much already and after all, the main wear parts are replaced now. I need a car just for the next two years. Would you, in my situation, invest in a head gasket repair?

Thank you so much for reading and for the help!


  • Ella :blue_car:

If there were a blown head gasket or a bad thermostat, you wouldn’t have been able to go on a long drive without it overheating.

But if the radiator fans don’t come on in stop and go traffic, the engine will overheat.


Maybe the head gasket was already bad, but maybe it just went bad because of the recent overheating. Who knows. It is not going to be a cheap fix but also you won’t get $3000 for the car in its current condition. If the engine is not running, they will just pay you close to scrap metal price.
How many miles on the car? Seems like the previous inspection turned out fine, so I am assuming there is no rust and the rest of the car is in good condition. This is going to be a tough decision.

Since the radiator was leaking the replacement may have caused the coolant pressure to increase. This possibly may have pushed the head gasket problem. If the head gaskets really do need replacement I think it would be worth doing. Once that is done you should be fine for some time after these repairs are done. Make sure that the timing belts and water pump are checked also. If they haven’t been replaced yet then that should be done also at that time.

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You might ask Mr. Mechanic if he has checked to see if the cooling fans and the sensor that turns them on are working. He might also check to see if the sensor for the temperature gauge is working right. Did he recheck to see if the belts he did replace are properly tight?

When the engine overheated again recently, was the coolant low, or was it strangely normal? He can pressure test the cooling system overnight and see if it can sustain pressure, or if it leaks down. He can replace the radiator cap, especially if the coolant was low after the overheating even though the overflow bottle was still right.