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"Does anybody have any advice on how to evaluate the diesels on used boats? Will a good surveyor be able to adequately check the engine over?"
A diesel mechanic is who you are looking for. He can do a compression test, engine oil analysis, and borescope the cylinders (if he has a borescope). Oil pressure will tell you about the bearings. There should be a maintenance log, and a visual inspection will give a clue to the quality of the maintenance. The engine should be clean and without leaks. Look in the bilge area under the engine.
Others can tell you better than I can, but I believe that Atomic is gasoline, and Universal is a diesel Atomic. I was looking at the Westerbeke website the other day , and I got the impression that Westerbeke distributes the Universal. I like the bore/stroke ratio on the Westerbeke better than the Yanmars; the Westerbeke should have a flatter torque curve. I haven't been able to see the power curves on Yanmar (not on their website), but I did note that they like to exaggerate their horsepower ratings; look at the continuous power rating at 2900 RPM. How they get an additional 10% more horsepower from 100 RPM is a mystery to me. Also note that the displacements for a given configuration (2, 3, or 4 cylinders) are different between the two brands; the strokes are close to being the same, but Yanmar goes to a bigger bore. Yanmar markets to the yachting segment. I have the idea that the government is Westerbeke's major customer, hence the red paint all over everything like an industrial engine.
IIRC, rules of thumb for engine selection are 1 HP per foot of length, and 2 to 2 1/2 HP per ton of displacement.
The only diesel engine I have torn into is a 4-71 GMC, so I can only offer impressions about these engines. Hope it's been some help.
Last edited by jones2r; 01-09-2007 at 12:45 AM.