Engine - MOH or Repower?

[Talk Story]

It has been quite a few years since I had a cruising boat and I have a contract on a boat whose engine 'purred' at the showing, but has lots of issues.
The engine is a 1989, 77HP Yanmar and during the survey it was determined that it had no engine coolant, almost no transmission fluid, a bad starter and a hot alternator - all at about 4,200 hours. The engine has probably been this way for a couple of years and it has been started and run for 10 minutes a couple of times a month during that time. Not enough to overheat, but not good for the engine.

When I first looked at the boat, I was hoping to put some money ($2-$3K) into the engine to get it to 6,200 hours, but something tells me that if the current owner let all of those sytems sit like that, there is more to be done. Even without the survey in hand I can tell it needs a new starter, new alternator, trannsmission rebuild, a new heat exchanger, etc.

Rebuild? Repower? Wait to find a boat that someone else repowered?

[Pegu Club]

Two schools of thought on this, you can do either the rebuild or the repower, tally up the cost of parts and future Maintenance and longevity VS a repower, and and a new engines maintenance needs and longevity. From what you described it might be that a repower Is the way to go. The lack of maintenance by the PO makes one think it could be quite the mess when you get into a rebuild. There are lots of boats out there, so maybe a different one with a healthier engine, Just my two cents...

Fair winds,

[a64pilot]

It’s usually way less expensive to overhaul and way less problems as everything fits, engine mounts, engine panel etc, etc, it’s just a matter of R&R and the overhaul.

However I’d not give up on it, I’d be surprised that with good preventative maintenance that you don’t have years left in it. If it cranks easy, doesn’t leave a smoke trail after being warmed up, has good oil pressure, it’s most likely not bad.

On edit, personally I wouldn’t consider a repower unless the engine has some kind of inherent problem, known to be problematic, parts difficult or impossible to get etc. or if the boat was way underpowered or something.

You won’t know until sea trial, fill up the fluids and take it out and run it, run it hard for five minutes, if your really interested install a mechanical oil pressure gauge, and or get an engine survey

[flyingfin]

Go for the full rebuild, since the was closed cooling, but only if you can find a top quality diesel shop to do the job and you can obtain all parts, including rod bearings

[Pete7]

Have the starter and alternator rebuilt. Give it a really good service perhaps with a flushing oil, then take it for a run. You are in for a few hundred dollars, but if it works you have saved thousands. Exhaust elbow for carbon and the internal state of the exhaust hose also worth checking.

Pete

[ABJ87]

I’m in the get it running first camp. A 77 hp Yanmar is not a cheap engine, it’s worth trying to save. If you do decide to repower a running engine will sell for a lot more.

[tkeithlu]

Are you ready to take on a project boat at this time? You have not had a boat in awhile, and this one has the potential to keep you ashore during both the engine rebuild/repower and during all the other repairs and upgrades to a long (negected?) boat.

[grahamj]

If you've already priced in the starter and alternator what's the problem in running the rest until it quits?

[Exctyengr]

I don't think that you have enough information yet on the true condition of the engine and accessories. Obviously, if the starter and alternator don't work, you know these need to be replaced but unless the bearings are shot or the engine has overheated, it might be fine. As others have suggested, plan on replacing what you know is bad, get a good engine survey by a qualified, Yanmar experienced technician and negotiate from there. If the engine does need an overhaul, I would probably overhaul rather than replace. It is a lot easier.
Keep us informed and good luck.

[Talk Story]

Thanks for the replies; there is stil much to learn about the engine, but to one point made here, yes it has been a long time since I was on a boat and a minor refit is becoming less appealing.

[GeneM]

I have two engines, rebuilt one and did a long bock for the other. The long block isthe way to go!

[JohnBlythe]

I would add. If you have any mechanical ability and can remove the starter
and alternator do so. Take them to a reputable electrical shop and have them tested, repair or replace as necessary. Reinstall and TOP off all fluids.
Let it run in place till normal operating temperature is reached. Simply listen for any abnormal sounds. If you hear any shut it down. If not gently
increase the load. If you have the engine new break-in procedure USE IT

[RaymondR]

Originally Posted by a64pilot

It’s usually way less expensive to overhaul and way less problems as everything fits, engine mounts, engine panel etc, etc, it’s just a matter of R&R and the overhaul.

However I’d not give up on it, I’d be surprised that with good preventative maintenance that you don’t have years left in it. If it cranks easy, doesn’t leave a smoke trail after being warmed up, has good oil pressure, it’s most likely not bad.

On edit, personally I wouldn’t consider a repower unless the engine has some kind of inherent problem, known to be problematic, parts difficult or impossible to get etc. or if the boat was way underpowered or something.

You won’t know until sea trial, fill up the fluids and take it out and run it, run it hard for five minutes, if your really interested install a mechanical oil pressure gauge, and or get an engine survey

Good sensible post.

[Hoodsail]

Assuming the rest of the boat passed the survey without major issues, so engine is the only potential big $$$ for you..would price out alternator, tranny, and starter repair/replace & installation and reduce your offer by same amount. As noted earlier the engine might be fine, could also do a compression check to see if all cylinders read out about the same & close to spec...I have a 1978 westerbeke, 4 cylinder, that runs strong & starts quickly that may have been rebuilt once in the 1990's, so marine diesels are "bullet-proof".

[kmacdonald]

If you are doing the work yourself, rebuild. If not buy a Beta.

I wouldn't consider either option until I knew the engine was worn out. A new starter, alternator, rebuilt or new gear is a lot less expensive.