95 Mariner 90 power head

[bstig60]

I recently purchased a what I believe to be a 9590 hp mariner on a 17 foot Key West. The middle and bottom cylinders have 95 lbs compression the upper cylinder has none




Any thoughts?

 

[GA_Boater]

The top piston has a hole in it. Lean mixture probably caused the hole.

 

[racerone]

Remove the 20 or so bolts on the exhaust cover and have a look at the top piston.

 

[bstig60]

We replaced the powerhead with a new one from Mercury at great expense, but now the engine runs fine.....

 

[racerone]

??---Not sure why you would do that.---But did you determine what caused the problem, yes or no ?----If not then be prepared !

 

[bstig60]

Yes, the boat had set for some time, the seller didn't bother to tell us how long. The carbs were lean and it blew a hole in the top piston. We had a new oil pump installed and the carbs gone thru and adjusted properly. We got a years warranty on it, so hopefully, it will be OK.