I have a OMC chevy 4 cylinder that will run at idle or low power all day long but if you increase power above say 30%, it will sieze the engine after about 30 seconds. The engine is siezed and the starter will not turn it over at all. The engine looses power, shutters and siezes. About a minute or so later, the starter will turn it over and it will restart. Water flow is good into the exhaust manifold. I noted that the rubber hose feeding the exhaust manifold was very hard to squeeze at power. Temp indicator shows 160 deg the entire time. Almost acts like the exhaust / water exit is blocked or something. Should the rubber hose feeding the exhaust manifold be hard as a rock with pressure when its dumping down into the lower unit? Engine seems to be controlling at thermostat temp and the engine does not feel hot. I am beginning to think the exhaust / water dump passage is partially blocked. Maybe back pressure is stopping water flow? Engine was rebuilt and performed well three times out. Fourth time down in the gulf, we went aground several times before getting out to the bay. Noticed the water temp dipped down for a few minutes at one time. After running aground in soft sand several times, we opened the throttle for the first time. thats when the engine first siezed up. It is siezed! starter wont budge it until it cools for a few minutes. Same thing every time now. timming is right, carb replaced thinking lean mixture but no change. Thermostat replace for the heck of it. Water flow verified into the exhaust manifold at at least 5 GPM. Note the rubber feed hose to the exhaust manifold is rock hard at 75% power. why so much pressure on this hose? Back pressure?
Ga cannon
Ga cannon
