by Pat Goss
There’s a lot more to checking for an overheating car than just belts, hoses and the thermostat. See, lots of times debris will clog the front of the radiator or the front of the air conditioning condenser. And when you look through the grill, the only thing you really see is the front of the condenser. If that’s dirty it needs to be cleaned, but maybe it looks perfectly fine.
Sometimes what we find is that debris has collected between the condenser and the front of the radiator. This is actual debris that we took out of a car, and we have now glued it to this radiator. That’s what it looked like. Now, you need to get rid of all of this stuff. How do you go about it? Well, one thing that you don’t do is you don’t use a brush, simply because the brush can damage the fins on the radiator and it can lead to poor cooling efficiency. So no brushes. You can use a garden hose as long as the pressure isn’t too high. You do not use a pressure washer. But the garden hose has to be applied to the back of the radiator so you’re pushing this stuff to the front. You could use compressed air to do it, or you could use a vacuum cleaner. But be careful not to damage the fins in the radiator.
All right, so that’s one problem that we see a lot of. Another problem deals with the cooling fan. Virtually all cars these days have electric cooling fans. Now, these are controlled by a temperature sensor that’s immersed in the coolant. The temperature sensor sends a signal to the fan relay, a little black box usually like this. It controls the flow of electrical energy to the fan. It turns it on. All right, now, as these fans get older, the bearings in the motors wear. When they wear, the fan turns more slowly so it doesn’t move as much air through the radiator. It also draws more electrical energy.
So if you have a repeated failure of the fan relay, that usually suggests that you have a bad cooling fan motor. Have your technician check it using an amps probe to see if the current draw is more than it should be. And don’t be surprised if you have to replace the cooling fan. Some tips that are a little bit different about overheated engines.
If you have a question or comment, write to me. The address is MotorWeek, Owings Mills, MD, 21117.