2002 Utopia Merc M2 210 Compression

[sahalstead]

I had my boat in the shop to get plugs changed, pump oil, etc... The mechanic told me he ran a compression test and that one side showed 120 compression on all three and the other was at 110 on all three. He said because they were the same on each side that it wasn't much to worry about. It strikes me as trouble on the way. Can someone please chime in and let me know your thoughts? What is possibly causing this. Thanks!

 

[Dr Honda]

I would also say things may not be happy. The Merc engines are normally 125~135, depending on the version. So... 110 psi is starting to get low. When the compression starts to drop... that means the rings are leaking. When the rings leak... hot combustion gasses get past them. When that happens... it over heats the pistons, and burns away the oil that is trying to protect the engine.

And....

When that happens... you melt a piston.


I guess if it was mine... I would double check the compression, and go from there.