OK Guys I need some Ideas. Here is my story. Last summer I broke a ring in my 1983 140 hp Mercurser Last Fall I pulled motor and had a sleeve installed put it all back together with new termostate and raw water pump in foot. Ran it on muffs to set timing and check for leaks every thing looked and worked fine. Due to high water in march thrugh May boat sat on trailor wating for water to resede. Finally put it in the water last weekend and made one round with a skier (Me) When i was swimming back to the boat it blew a hose off. Steam went every where. Temp was pegged at 240. Drug it back to the bank let it cool pulled the thermostat out filled it back up with water after replacing hose cranked and ran fine for 3minutes and temp went back to 240 pulled it out of the water hooked up the muffs water is circulating through heat exchanger so I know there is no restriction then pulled the water circulating pump cover nothing broken there. put it all back together ran again on muffs and it still runs hot just takes longer for it to get there. I check all hose for kinks and put laser thermometer on heat exchange hosees 220 on the exchanger in and 190 out.any ideas would be greatly appreciated. also checked plugs and compression and for water in cyl. or faulty temp quage . Maybe head gasket no problem there. tired of scrathing my head.
