A car that always runs hot may need to be seen by a radiator specialist.

Dear Car Talk

Dear Car Talk | Jul 01, 1993

Dear Tom and Ray:

My wife owns a 1987 Nissan Sentra. She is always concerned about the temperature gauge reading close to or at the end of the "H" range. This happens especially while going up hills on hot days. The dealership checked it out and diagnosed the thermostat as the problem. They changed it and the problem still occurs. One year later, we changed it again. Still, not much of a difference. We've changed the radiator cap, flushed out the radiator, and added new antifreeze as was suggested by the dealership. Still, no change. Neither the radiator nor the water pump leak, and all the belts are fairly tight and new. Is it normal for this make and model to be doing this? Please help put an end to this frustration.

RAY: Well, John, I usually put an end to this sort of frustration by selling the car to a close family member. Then I stand in front of a mirror and rehearse the line: "Gee, it didn't do that when I owned it."

TOM: This car is certainly old enough to have a plugged up radiator, John. And flushing out the radiator with a bottle of "radiator tidy-bowl" you buy at an auto parts store is not necessarily going to clean it.

RAY: You should really take the car to a radiator shop. They'll take the radiator out and "flow test" it. If they determine that the passages inside the radiator are clogged, then there are a couple of choices.

TOM: They can try acid-bathing it. I used to do that to my brother when mom wasn't around. If that doesn't work, they can always replace the radiator.

RAY: And if the radiator's flow turns out to be fine, then I'd suspect a weak water pump or even a leaky head gasket. Good luck.

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