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I drive a 1993 Chevy Corsica which has had an internal water leak for 3 years. I am told by mechanics that the water is going into the engine block or that the heater core needs repair. Because I cannot afford the repairs, I keep the overflow tank filled to prevent overheating. In the winter I add 50/50 coolant, but in the summer, to save money, I use water. As I understand, using water can cause quicker corrosion to certain parts that the water flows through.
My car has lost some power recently when I need to accelerate. I know there are probably many reasons why this could be happening. But my question is that if I were to presume that the other causes were to be ruled out, where should I look first for a problem that is caused by the prolonged use of water as a coolant for an internal leak during the last 3 summers and in what order to look for them.
For instance, maybe start with checking the spark plugs for corrosion and moving on from there.