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New radiator but car is still overheating on hills

1998 Subaru Outback, 170K miles

While driving up a 5-mile hill recently, my car overheated. I checked under the hood, and the radiator fluid was gone. I filled it and took it to a mechanic.

The mechanic found a hole in the radiator and replaced the radiator ($500). The car runs fine on flat ground, but when I tried driving that 5-mile hill again, it overheated.

The car is back with the mechanic, but he says that he can’t get the car to overheat.

Any suggestions/help would be most appreciated.

The overheating from loss of coolant may have damaged the head gaskets. Subaru engines don’t tolerate overheating very well. I’d test for head gasket leaks.

Ditto to McP’s post.

I’d like to add that perhaps another mechanic is in order. Rather than trying to get the car to overheat again, he should be checking som ebasic stuff like cylinder leakdown (especially on a Subie), coolant flow, coolant system pressure testing, stuff like that. He should be able to diagnose the problem without making the engine overheat…which he should not be doing anyway.

Where it’s overheating only under load, my guess is also a headgasket.

If you have to go up that hill again, set the heater on full hot with the fan at top speed. This fixes nothing but might save some coolant.

Before you spend a lot of money, spend a little on a new radiator cap. New radiators do not come with caps and overheating on uphill drives is a sure sign of a cap thats not holding pressure. You can’t go by visual inspection either.

Ditto Keith and I would add change the thermostat when you change the radiator cap. Rocketman

Well, and the winner is . . . it was the head gasket. They took out the engine, replaced the gasket (and timing belt and water pump since they already went through the trouble of taking it apart), and it now drives as good as new (almost) – two grand later. Thanks for the suggestions.

Thanks for letting us know the outcome. These repairs aren’t cheap, but they’re much less than the cost of a new car. Now you can drive your Subaru another 170K miles.

You’re using the singular version of the word “gasket”. Hopefully the plural is what was done.