3.7L Mercruiser knocking and power loss

[newberryfam]

I have an 3.7l mercruiser that I am having problems with. I had it out last week and everythng ran good. Today I took it out, it ran good for about ten minutes and then all of a sudden it sounded like a vavle started knocking and a major loss in power. At full throttle, I cannot get the boat over 10mph. When I put the engine at idle, the engine stops. The only way I can keep it running is if I keep the rpm above 1500 rpm and it still has a knock. Is there anyone who might be able to help me so I know where to start looking? Thank you.

 

[P 0 P E Y E]

Re: 3.7L Mercruiser knocking and power loss

Something has happened and now it's going to be a puzzle to solve.

I would suggest the following initial checks

Check your oil look for chocolate milk (water infiltration)

If no, check your fuel water separator for a whole bunch of water. Is there water in the gas? if yes fix it.

Check spark plugs for evidence of water, most like from the exhaust manifold or riser.

Report back here.

Welcome to the forum by the way. You posted in the right area. Some big gurus are here and will post any minute some helpful and enlightening tips.

 

[Bt Doctur]

Re: 3.7L Mercruiser knocking and power loss

Check the engine oil level
If in doubt it`s the engine, pull the drive and retest for knocking
remove valve cover and see if all the valves and springs are intact.
rotate engine making sure all rocker arms move
compression test with carb wide open.
report back with your findings

 

[newberryfam]

Re: 3.7L Mercruiser knocking and power loss

OK, So I have opened up the motor and have found 1 bent push rod. I have looked over the rest of the engine and cannot find anything. I checked the timing and it is dead on. Is there any ideas of how this happened? Do these things just happen?