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Warning display screen indicated that the car was low on engine coolant and was overheating

Q: I drive a 2000 Cadillac Seville with approximately 100,000 miles on it. Recently, the warning display screen indicated that the car was low on engine coolant and overheating of the vehicle was subsequently occurring. The dealer suggested that I either replace the radiator or water pump. I opted for the new radiator since the water pump and thermostat had been replaced at 55,000 miles. The problem, however, continued and a new water pump and thermostat were installed. Still, the problem persisted and you guessed it, the coolant reservoir had to be replaced. That solved the problem. Is there a test other than trial and error to determine where coolant is leaking? I enjoy your column and look forward to your answer and comments.” Thanks in advance.
Ken G.

A: Coolant leaks require a visual inspection to locate them. It is a simple procedure using a tool called a “Coolant Pressure Tester.” If a vehicle comes in with a coolant leak, the first thing we do is look at all the components in the system and see what part (or parts) are leaking. GM vehicles use Dexcool, which is red and easy to see and will also leave a stain you can follow back up to the source of the leak. If the leak is not obvious, we attach the Pressure Tester to the cooling system and increase the pressure. Kind of like a garden hose, you may not see the leak until you turn on the water. Guesswork is never required, if you can’t see the leak, don’t replace the part.