coolant pressure

[jeffkemp]

i have a 485 merc cruiser rebuilt with a 3inch heat exchanger and my coolant fluid is pressuring up and blowing out my rad cap. Lost all my coolant out of my engine and it was replaced with lake water. Is this a crack or hole in my heat exchanger or something else? How can I test to see what the problem may be

 

[stonyloam]

Re: coolant pressure

Possibly a blown head gasket pressurizing your cooling system. Need to do a cooling system pressure check and a compression check. You can borrow the tools to do both from Autozone.