Find out what causes engine overheating-- and how to fix it

Dear Car Talk

Dear Car Talk | Aug 01, 2008

Dear Tom and Ray:

I was coming home from bowling the other night, and I passed my buddy going down the road. So we stopped in the road and were talking. Then all of a sudden he asked me, "What the heck is that?" I looked up at my engine, and it was either steaming or smoking. I was worried, so I popped the hood, and we opened it up. You definitely could smell antifreeze burning, and the smoke was coming from the radiator. Do you think that I have a bad radiator and need to replace the entire thing? Now there is antifreeze coming from under the car, so someone told me to put Bar's Leaks in the radiator. Oh yeah, I have a 1991 Pontiac 6000 LE, with a V-6. Thanks. -- Travis

RAY: I'd start by checking the simple stuff first, Travis. The thing I'd suspect first would be the cooling fan.

TOM: Let's say, just for the sake of argument, that your cooling fan bit the dust at some point. Like in 1998. Or last week. You might not have noticed because as long as you're moving, air is flowing through the radiator and helping to cool the engine.

RAY: It's only when you stop, say, at a railroad crossing, to let a 200-car freight train go by, or to chat with your buddy, that you really need the cooling fan to simulate the airflow you normally get when the car is moving.

TOM: So, while you sat there chatting for five, 10, 15 minutes, with no cooling fan, the engine was getting hotter and hotter. Finally, it overheated, your coolant boiled over, and that boiling coolant blew a hole in a weakened hose or maybe even the radiator itself. That explains the steam, the smell of hot coolant and the puddle under your car.

RAY: Now, it's possible that with a car this old, you may need a cooling fan, a new hose, a new radiator AND a new engine as well. So there are no guarantees here, Travis. But start with the simple, inexpensive stuff first, and take it a step at a time.

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