Did you know that a bad ground could cause electrolysis in your engine's electrical system? Use a digital voltmeter capable of measuring millivolts and attach the ground probe to the radiator. With the engine running, dip the positive test lead in the coolant not touching the radiator. If the reading is more than 150 millivolts, the coolant may be excessively acidic. If it reads anywhere near 300 millivolts, try adding a good ground from the chassis back to the battery.