Overheating 50 HP 4 stroke

[Seaduced]

Alright?. Lets see if you guys can come up with something here we?re missing.

50HP working great.

One day starts to overheat at high RPMs
Runs like hell?. Alarm goes off.

Let it cool and runs great till higher RPM.

Okay.. something is screwed up. Lower 2 cylinders running 30-40 higher than the top 2.

Step one: Replace water pump parts (didn?t need it but did anyway)? one, same problem.

Next Check compression for the worse case?. Checks all in normal compression and less than 5lb difference. Passed leak down test.

Okay bad news, need to pull the head, but all chambers were very clean, no blockage.

Pulled power head next, no visible blockage.

I?m out of ideas?. Anyone please help!

 

[longshanks]

Re: Overheating 50 HP 4 stroke

if it's an older model, and it's been run in salt water, you may want to do some research about a possible corrosion-related blockage between the power head and mid-section. I remember that some of those motors had a plate that would corrode and restrict cooling water passage, leading to overheating eventually. If so, the powerhead needs to be pulled and this part replaced. I'd do some online searching first. good luck.