rebuild or repower

[Ereiss]

Well, learned that the 20 year old 3gm30 has a bent rod or piston (described as a "hard spot" when they try and turn it in the forward direction). Will have a discussion with the yard this weekend about the possibilities of rebuilding or replacing. Don't have costs for either yet.

Anyone have advice? I do realize that the 3gm30 is undersized for the F38 so one benefit of repowering is getting a proper sized engine and having a fresh engine when the time (hopefully distant) comes to sell her. Obviously the disadvantage is some delta in cost.

Thoughts or experience would be appreciated.

Still p**ssed at myself for causing this, arrrgh.

[GeoffSchultz]

Ed,

Sorry to hear that this was the diagnosis. I can certainly understand your frustration. Costly lesson! I've learned to close the seacock as soon as the engine doesn't start right away.

I don't have any direct experience with repowering. I'd suggest that that you talk to various engine places to see how much the options are and then make a decision. Clearly a newer/higher-HP engine would be great, but is it worth the cost? Also, I guess that after taking that diesel engine course a while back that you're not up to rebuilding it, huh?

-- Geoff

[Ereiss]

yes, the lesson was about a year's tuition. Even though I was start student in the 3 day diesel class, I think a rebuild would be well beyond me what with still having a full time paying job and living in a condo (the space/time continuum). I'll see what Burr Brothers has to say on Saturday on my choices.

Thanks for the condolences.

[Mike Holibar]

Hi Ed,
sorry to hear about your engine. Have you reached any conclusions yet ? A bent con rod might not necessarily mean a full rebuild is required. Iv'e had a bit to do with this sort of thing over the years and there are quite a few points to consider. If your engine is in good condition corrosion wie it may be worth keeping. 20 years of age could mean less than 5000 hours on the clock so plenty of mechanical life remaining. If it is heat exchanger cooled, that might be another matter.
Next, if you repower, replacing like with like is the most economical option beacuse you should be ablt to get away with reusing the propeller, exhaust system (same size and side), mounts and mounting positions, fuel lines, wiring, auxilliary equipment such as freezer compressor and so on. If you go to a bigger engine practically all this will have to change, different mount positions maybe modify beds, new larger exhaust system, gooseneck and through hull, bigger seawater suction, new brackets and pulleys for auxilliary gear, modifications to engine space, new propeller - is there enough room to swing a bigger prop? possibly a bigger prop shaft will be required, and once you have gone to all this expense, you'll have to buy the engine as well! The 3GM might be a bit light for the job but it is a good engine and very capable when matched with the right prop for the job. I had one in my Rasmus 35 which I thought was a bit small. I changed the reduction to 2.8:1 and matched a bigger prop to it and it was like getting a new engine - that might be worth considering to get a little better performance.

Best wishes,
Mike.

[Ereiss]

Mike, thank you for your thoughtful note. Well I decided to go for the rebuild by Mack Boring. while people say the 3gm30 is undersized I really found it adequate and given that replacing it with larger would double the cost of the whole operation I'm good with my decision.

Now if the weather will stay fair through the end of the month (boston area) I still need to get the boat to Bristol, RI, a 50 mile trip after the work is completed. Think warm thoughts.

[Mike Holibar]

Good call Ed. Warm thoughts thought!
Cheers,
Mike.

[Ereiss]

Thanks, Mike. Just learned engine isn't repairable. Bent crankshaft took out some of the block. When I screw it up, I really do it to perfection, no?

Well, nice shiny engine will add to boat value some day.

Have a good weekend.

[Mike Holibar]

Bad luck Ed. I suppose lowest cost option would be to replace with the same engine if you can get one or alternatively if a short block is available you could transfer the marine components over.
Best regards,