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Re: Compression test 2GM20F
500 naut.miles would be 100 hours at 5 kts. A 2GM20 only holds 2 liters of oil in the crankcase. So, you burned about a liter, maybe a bit more, in 100 hours. That's probably more than a new engine will burn, but not a huge amount. I would keep a closer eye on the oil, check it every 24 hours or so of run time. And try running as heavy an oil as the manual recommends. In Singapore I would think you could run at least 40-weight, maybe 50-weight (but check the manual). In any case, avoid multi-grade oil, as it tends to "thin" more easily over time. And make sure you are using diesel engine rated motor oil, NOT oil for gas engines.
Also, I agree with asdf38. If you can get the revs up, but the boat isn't getting close to hull speed, it's not the engine that's the problem. A 32' Hunter shouldn't displace enough to over-burden a 2GM20, IF everything else is OK (if she's seriously over her designed displacement, that's another story). What size/pitch prop do you have? Are the bottom and prop clean? Is there something else on the bottom that is making it "un-fair"? Are the clearances between the prop and the hull, and the prop and the rudder adequate? Were you towing a dink? Was there a serious headwind?
"If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." --- E.B. White
Last edited by Puddin'_Tain; 05-12-2014 at 12:31 AM.