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Old 22-02-2016, 19:44   #16
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Re: Why switch to a new engine

In my experience the main reason to replace an engine is that it needs a rebuild or overhaul. The cost to do that is often more than half of a new engine, and the new engine has a higher power/weight and more efficient and cleaner burning - and a lot quieter. Also quality repair parts can be hard to find on older engines.

If the engine is in good shape, any current problems fixed with quality affordable parts, then I would say that it is simply not worth considering replacement at this time.


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Old 22-02-2016, 21:45   #17
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Re: Why switch to a new engine

Well it seems as if the general opinion on this forum is to keep the engine and stop bugging all of you . This was kind of already my idea.

However it seems as if the general opinion in the states, where I believe most of you live, differ from where I live. It might have something to do with the fact that I live within a mile or so from the Volvo Penta HQ. I'd say that a majority of the sail boats built in the 70's and 80's now have replaced engines. However I like my 2Gm20 feels that it has enough power and I am not really keen on changing it.

What I wanted to hear were different failure modes, I can foresee a number of things, the mixing elbow being the most likely and probably worst failure. However continuous degradation of the engine is unavoidable but this does not happen over night. What I don't want is to have my vacation ruined by an unforeseen break down.

Regarding the engine hours, I have no idea, there is no hobbs meter. But I would guess 3-5000 hours.

Thanks anyway for all of your answers, still it would be interesting though to hear about actual failures and the failure modes.

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Old 22-02-2016, 22:10   #18
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Re: Why switch to a new engine

Lack of use seems to be really tough on diesels. I have seen them replaced with hundreds of hours. Failure to drive the engine, aka babying is actually rough on the engine. Short runs are rough.

If it starts well, doesn't smoke and isn't leaking, then why bother? Friends ancient Morgan 30 Perkins is still running strong.
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Old 22-02-2016, 23:05   #19
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Re: Why switch to a new engine

I replaced my 3GM30 in 2011 for the reasons you stated.

In 2012 a friend who owns a small marina needed to install some 18m 12" x 1/2" wall piles after the marina got wrecked by a flood. Since he was short on funds we built a pile drilling machine using bits of the wrecked marina for the floaty bits, parts from an old forklift he owned and powered it with my old 3GM30 which I had supposed was on it's last legs.

When we installed the piles the engine was required to run at full throttle for about five hours per day for about three weeks. I thought that under that service is would just lie down and die but it never missed a beat.

The engine was about 24 years old at that time and from what I observed I think it would probably be OK in another boat for about another 24 years. It is the raw water version and I checked it fairly regularly for corrosion and was unable to find any.

The belt drive Johnston, impeller type water pump">raw water pump had been replaced a few years before I removed the engine from my boat. When I priced a manufacturers spare pump I was quoted in excess of $850 for a new one. Since I had already priced the equivalent Johnston pump in a pedestal type and had been quoted less than $300 I used a piece of alloy angle to make a new mounting bracket thereby saving myself $500. I did the same with the alternator when it required replacement using a fairly low cost Bosch 85 amp model to replace the original 55 amp they wanted and arm and a leg for.

The GM series Yanmars are fantastic little motors and with the limited hours they run in boats have decades of life in them.
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Old 23-02-2016, 02:17   #20
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Re: Why switch to a new engine

If it ain't broke, don't fix it (regular maintenance not withstanding)

I've never heard of someone replacing an engine purely due to age.
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Old 23-02-2016, 07:57   #21
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Re: Why switch to a new engine

My record for a deisel engin is over 500,000 miles, assuming a 40mph average thats 10,000hrs. The service book said to change the pistons and liners AT 1,000,000 miles, yes it had a documented million mile service. Anyway you get the drift, if it ain't broke don't fix it. Most boat engines die of under-use and neglect way before the end of their service life so if there are no problems it's fine. Only advantage of a newer one will be that it is lighter and smaller for its power, which may also meet it has a shorter life!
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Old 23-02-2016, 08:29   #22
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Re: Why switch to a new engine

Just to mention:
old engines: 1500-2200 RPM, NO Turbo, No electronics
new engines: upto 3300 RPM, Turbo starts working at 2200 RPM, electronic controlled

saying: keep it simple. Things you have not got can't brake.

I would never ever change my Ford Lehman 85 hp with 1800 rpm (5,5l/hr) for a bloody new 50hp turbo (makes 85hp at ease) with 3l/hr

for the disadvantage of an unrepairable (on board) engine that lasts 40% of the old ones due to rpm's like in cars.

Think this is short and understandable.

p.s.: same with OLD Yanmar, John Deere, Mercedes OM, Volvo makes.
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Old 23-02-2016, 08:32   #23
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Re: Why switch to a new engine

I had a small Yanmar aircooled diesel running a generator, that after at least 30,000 hours (probably closer to 40,000 hours really. with mimimum 30 hours a week over 25+ years) which was still purring like a kitten when I donated it to a neighbour that needed a genny (I think it's still running ok too, it was last time I saw him).

With regular oil and filter changes, the only thing that failed was several changes of starter cord. and a silencer, so I shoved a small stainless steel one on it that I picked up cheap from a scrap yard.

PS Treat turbo's right, and they shouldn't fail for a very long time. The secret is to tick them over for about a minute at startup, to make sure the oil is getting to them before revving, and before you switch off, let them tickover for a minute, to get the revs down so you don't cut off the lube feed while they are still spinning fast.

I have never had to replace a turbo (though I do much prefer superchargers).
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Old 23-02-2016, 09:03   #24
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Re: Why switch to a new engine

PS Treat turbo's right, and they shouldn't fail for a very long time.

Friend of mine is servicing a pilot boat with 2 years old 2x 850 Hp turbocharged engines. One turbo was done after 14 month.
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Old 23-02-2016, 09:03   #25
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Re: Why switch to a new engine

The problem is, if your engine fails on a long trip or in a remote area. Then it is difficult to replace the old one with a new engine.

A lot of parts has to be changed. You probably need another propellor and the prop shaft.

Engine bed has to changed. Other instrument panel, remote controls, exhaust system etc. etc.

Better look for a used engine of the same type. Service this engine and keep it for spare parts. Or as a replacement for the present engine after a faillure.

Replacing an engine with same type is very easy to do. And a used older engine of same type is cheap to get.

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Old 23-02-2016, 11:18   #26
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Re: Why switch to a new engine

Although I recently sold my boat, it had a 1985 Volvo Penta B2002 (18hp). It was over 30 years old. It started instantly, even after the winter layup. It ran perfectly, every time. Did not smoke, leak, or burn oil. I kept the filters clean, and changed the oil regularly using the cheapest oil I could find. The more I used it, the better it ran.

IMHO, age is not an issue for a diesel engine. Abuse, neglect, and bad fuel cause diesels to fail. Keep your awesome yanmar, and enjoy your reliable, economical engine.
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Old 23-02-2016, 13:06   #27
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Re: Why switch to a new engine

Have a 65 HP perkins diesel 4-236 in my 73 WHITBY 42,IT'S THE ORIGINAL engine.
After more than 9000 hrs it still runs great and I would not replace it without a good reason.My know how on diesels tells me not to buy any of those new engines and get
the old perkins rebuilt.
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Old 23-02-2016, 14:54   #28
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Re: Why switch to a new engine

I have a 3GM30 which is about 18 years old, and it's really difficult to know how many hours, but it's in California where we get to sail virtually all year. I suspect it's in the 2000 hour range.

The mixing elbow (more like a U-turn than an elbow) was pretty cruddy inside, and I had some modest cooling issues, so I replaced it with a polished SS unit available on Amazon. It was under $200 including shipping, and I suspect it will last the life of the engine, plus.

Along with excellent fuel filtration (oversized Racor spin-on filter), and annual oil changes, I think the engine should be good for a decade. While I might want a new, cleaner replacement engine, I find it incredibly hard to justify the $10K or so that would require. I'd rather have a new suit of sails, or a larger cruising budget or something else.

I also wonder what the cost would be to pull the engine and have it reworked. Obviously depends on the condition, but does it ever make sense to take a working engine with lots of hours, and simply rebuild it? Could that cost, perhaps, $2500 and leave you with another 15 years of life?


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Old 23-02-2016, 15:54   #29
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Re: Why switch to a new engine

Unless there is a particular reason to change engines at this time, why not let the engine itself let you know?

Old and sturdy vs. new, and far more complicated. You might stock up on a set of the stuff you'd need for a head rebuild, and rings, as well as the known weak spots. Catastrophic failure of old diesel engines is rare. Occasionally head gaskets get blown, sometimes cracked heads appear, but the engine will still run, although not as well.
Ring wear announces itself with blue smoke and oily exhaust. Then address the problems. Of course, if you're concerned about losing the fun of your vacation, then maybe you want to do some prophylactic maintenance prior to the holiday. If you've already done that, then you should be good to go.

Re-powering will be a headache.


Try and find an engine that does not have electronics checks to run through prior to starting. Can you imagine not being able to start the new one due to a computer!
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Old 23-02-2016, 15:59   #30
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Re: Why switch to a new engine

Why switch to a new engine > same topic, same OP, same post .... but with 2 pages of replies

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