Yanmar 3gmd Question

[nk235]

I had a 25' boat with an outboard but just put a deposit down on a 32' boat with an inboard Yanmar 3GMD. I do not know really anything about inboard motors but I do know Yanmar is very popular and makes a good motor.

I plan on having the entire boat surveyed but one of my concerns is this motor. The owner was a former mechanic rebuilt it less than a year ago and according to what he gave me he did:

Engine (Yanmar 3GMD 20 HP): The Yanmar 3GMD was completely rebuilt in 2007 to include NEW- Starter, Motor Mounts, Valves, Valve Guides, Pistons, Rings and Rod Bearings. Racor Fuel Filters, Fuel Lines, Fuel Pump and Engine Raw Water Pump have also been replaced

He says it runs perfectly and it only has 20-30 hours on it since the rebuild but my concern is that I do not know this person where is if the work was done by a yard I would have a warranty on the motor. Besides dropping the boat into the water for a sea trial, is there any other tests a surveyor or mechanic can do to see if this was rebuilt properly? Do surveyors usually include this? Is the Yanmar a complicated motor that I should be concerned with the fact that it has been rebuilt? How much does it usually cost to have a Yanmar mechanic inspect the motor? Is it worth it to do this or is the Sea Trial enough?

The rest of the boat is in immaculate shape and the owner has been very forthcoming about everything else so I believe him when he says it runs well, but I am not about to buy a boat on that. I want proof for myself. Any suggestions?

Thanks in advance

[timebandit]

You can ask for parts receipts and check the dates.

[JohnRPollard]

If you have serious concerns, it might be best (if only for peace of mind) to have a separate engine survey performed. This would be by a certified engine surveyor, not the guy/gal you've hired for the rest of the boat.

Personally, I would consider it a plus if the engine had been properly re-built. A bigger concern to me would be whether this particular engine is raw or fresh water cooled. You might also ask what precipitated the re-build?

Also, most 3GMs I'm familiar with had a higher HP rating (our 3GM30F for instance is 27hp peak, 24 hp continuous), but yours could just be an older version that I'm not familiar with.

Good luck to you!

[timebandit]

Check the log book.

[billangiep]

The 3GMD is raw water cooled unless a heat exchanger was added at a later date also I beleive the 20 HP rating is @3400 and the 22HP is @ 3600.
"QUICKLINKS"

Model	HP	from	to
YSE	8 & 12	1974	1976
YSB	8 & 12	1976	1977
YSM	8 & 12	1977	1980
2QM20	22	1975	1980
1GM	7.5	1980	1983
3GMD, 3GMF	22.5	1980	1983
3HMD, 3HMF	30	1980	1983