I have a 1988 Mercruiser 3.7L I/O, 4 cylinder, with closed coolant system and a heat exchanger using lake water to cool the coolant. First time out this year I noticed coolant in the plastic reservoir went from half full to overflowing. A lot of coolant came out of the overflow hole in the plastic cap on the reservoir.
I noticed the coolant metal cap at the top of the engine (looks and works like a radiator cap) was not tight and thought that might fix it, but it did not. Any ideas on why quarts of coolant would over flow out of the reservoir?
I noticed the coolant metal cap at the top of the engine (looks and works like a radiator cap) was not tight and thought that might fix it, but it did not. Any ideas on why quarts of coolant would over flow out of the reservoir?