You're not overheating, probably just missing a heat shield.

Dear Car Talk

Dear Car Talk | Jun 01, 2000

Dear Tom and Ray:

I really need help getting mechanics to take me seriously. I drive a '92 Honda Accord EX that runs hot. It overheats. In spite of having the thermostat replaced and the radiator back-flushed, the engine fan still turns on almost immediately after I park. The warmer the ambient temperature, the more aggressively the fan kicks in. It doesn't seem to turn on at all when the air temperature is under 35 F. Mechanics won't take me seriously. They all say this is perfectly normal, and the fan is doing its job, helping the engine cool down. "Yeah," I say. "Then tell me why the car is overheating." They say they don't know. They ask if the temperature gauge is above normal (it's not). But I can feel heat radiating up from the floor beneath the driver's seat like when the heater is on. What's going on? -- Jim

RAY: Well, I'll tell you what's NOT going on, Jim. Your car is not overheating. The mechanics are right that the fan is doing exactly what it's supposed to do. When you
turn off the ignition, the engine actually gets hotter -- briefly -- before it gets cooler. That's because the cooling system shuts off along with the ignition, and the ambient
heat accumulates in the closed engine compartment.

TOM: So a sensor reads the coolant temperature, and if it's above 200 degrees or so, it turns on the electric cooling fan until the temperature comes down to an
acceptable level. That's not only normal, it's necessary. So your fan is working fine.

RAY: And since the dashboard gauge reads normal, there's no real reason to believe that the car is running hot. The heat you're feeling is probably from the catalytic
converter that's under the driver's seat.

TOM: When this car was new, you had a piece of metal called the heat shield that sat between the top of the catalytic converter and the floor of the car. My guess is that
it's rusted off and has been missing since about 1998. Without the heat shield, some of the heat from that 800-degree converter is bound to penetrate through the floor
and provide an unwanted bun warmer -- especially in hot weather.

RAY: So instead of asking about overheating, ask a mechanic to check the heat shield -- especially the piece on top of your converter. And if it's missing, ask him to
replace it. And if you want to be taken seriously, Jim, do what my brother eventually did: Stop going into the repair shops in that silly Mary Poppins outfit.

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