Ask Bob: Overheating

by Bob DeP.

My friend's car has recently started overheating while driving. A repair shop thought that it was the thermostat, so they replaced it and refilled the radiator fluid. Two weeks later, while driving, the engine temperature gauge shot up. When they pulled over, they noticed that the radiator fluid level was extremely low. Do you have any idea as to what may be the culprit?
Nathan G.

Does the car have any leaks? There may be a small high-pressure leak that would not leave a puddle under the car. Nevertheless, you can still smell it. Antifreeze has a distinct sweet smell to it. To notice this "high-pressure" leak, drive the car around for a while, until the engine is up to operating temperature. Then park the car somewhere safe and open the hood. Look around at all the hoses, but be careful, the engine is hot.

You may see a small thin stream flowing from a hose, usually around the area of a clamp that has been overtightened. Another possibility is a bad radiator cap, or a small pinhole in the radiator causing the loss of coolant. The worst possible case is a bad head gasket. This can be determined by looking at the engine oil dipstick. If is comes out another or color than normal engine oil, i.e.. white, gray, creamy, mayonnaise like, then the coolant is entering the oil and you have a bad head gasket. Or you can go to the rear of the car and see if there is an antifreeze smell in the exhaust. The coolant is entering the cylinder and is being burned with the fuel. You may also see bubbling in the radiator. Another possibility is a bad water pump.
Good Luck!
Drive Safely!
Bob, The Auto Answer Man

Have a car care question? Visit our automotive maintenance section and see if we've already answered it or a similar question.

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