Too Many Engine Hours?

[karkauai]

Would be worth having a mechanic survey the engine. Might cost you $500+ but could save you a bundle.

[Elcapt]

Hi Everybody,

I have a 1988 Yanmar 2GM, raw water only with over 9K hours. It runs perfectly, have always followed maintenance.

the exhaust elbow has been replaced three times. Its a known problem.Keep a spare.

At 5K hrs I replaced injectors

at full load 3400 rpm pushing a 10 ton gaff rigger w 2 blade prop it will burn a little oil with 24hrs flat out running. Not bad.

For a 14 month world voyage in 2000-1 I refitted the alternator with a 100 amp w outside regulator, but no fancy battery stuff, only a 1-2 /both/ off/ switch. BUT if you run down a G27 battery to 12v then it must be started on the full spare battery and switched over to the run down one after warm up It will take 300 rpm off and belt will slip if not properly tightened. Then it will charge right up.

You will have to replace the exhaust elbow and keep an eye on it. Otherwise good fuel, and change the filters . I also have a fuel tank sump with an accessible drain/draw off hose to get the dark bugs off the bottom. It may not meet yacht standard, but it works brilliantly.

You may also have a problem;em with the drive/shock plate on the flywheel. easy to replace but nasty if the springs get weak.

The transmission drive cone can be a weak point and I would keep a spare. And learn how to replace it before voyaging.
Had to ship a new tranny into Patagonia when it lost fwd gear. very very$$!!

keep a few belt spares for water pump and alternator. Spare lift pump, injectors, starter, alternator, fuel filters, you will not have to worry about your motor.

keep many water pump impellers and learn to change them in 5 minutes. Plastic bags, jellyfish and occasional defects will put you in a bad position if you do not learn how to do this quickly and accurately.

You need to ascertain the history of the motor. Starting up to leave a slip or unmoor and shutting down is the worst possible thing. Must be warmed up and run hard a bit every time.


If everything else good, I might replace the gearbox or rebuild it at 5K hrs.

Best, for my 2c Elcapt

[Icarus]

Originally Posted by Roniszoro

Looking at a boat for sale with a 24 year old Yanmar with 4500 hours? What is a reasonable life, in hours, for an engine? At what point, in engine hours, are they normally replaced?

That's about 3½hr a week ...that's nothing.

I clocked up 11000 over the last 26 years on my 40 hp ISUZU
All it needed so far was a new fresh water pump and a cylinder head overhaul, filters and yearly oil change.

One normally one doesn't replace an engine unless there are major repairs required...

Some truck diesels have 4million miles on it.

[mdenize]

I'm no mechanic, but from experience the engines that I've had that lasted the longest are the ones that were designed and used at revs appropriate to long life. Eg a earth mover, tractor or displacement boat. All these tend to be heavy and designed to go all day for a long time, 10000 hours... no problem. Take the same engine and run it at maximum revs in a race car/boat/tractor and it won't last very long at all. In extreme cases an hour or two would be amazing. So while oil and everything plays a part in long life of an engine at the end of the day it's the nut on the wheel that is one of the main factors. So if like sailor boy you know how it was used for most of its life you have some idea of how long it's going to last.

[skipperpete]

I know that the OP has decided not to buy the boat but the question is still a good one. In his case it would have been useful to know which Yanmar model he was considering, a 3QM yanmar is one of the best small marine engines, possibly THE best followed closely by The GM series and both these models will reach 8-10,000 hrs before overhaul if the wet exhaust doesnt kill em ( or seriously wound), JH series are a little less robust, still good, but turbo’s usually indicate that a lot more power is being extracted from a less powerful base engine and with the JH’s it’s a 50 hp base engine that gets boosted to 125hp so fairly unrealistic to expect a long life for the turbo models. The YM series are not an engine I like very much but that base engine in an industrial application … frigmobiles, generators,farm equipment has a pretty good track record for longevity.

[Siberian Sea]

Engine hours are like miles on your car. It’s not so much how many miles of in your case hours but rather what kind of hours. If the engine was well maintained, never ran too hard and not excessive idle not under load it can last many more hours then what you have now. i have an Isuzu C-240 diesel in a fishing boat in Alaska that has just over 31,000 hours. It’s runs wonderful and has never been rebuilt. This is a 4cyl 60 hp engine. I change the oil every 150 hours and never run it over 1700 rpm. Of course normal things like the starter, alternator, water pumps, injection pump with injectors i have changed when needed.
So take care of your engine and it shall take care of you. You should be able to get over 20,000 hours with proper care.

[Epikur]

Diesel engine life expectancy is 30,000 operating hours.

[Dockhead]

Originally Posted by Roniszoro

Looking at a boat for sale with a 24 year old Yanmar with 4500 hours? What is a reasonable life, in hours, for an engine? At what point, in engine hours, are they normally replaced?

There is no answer to this. Sailboat motors get replaced or overhauled at 1,000 hours, at 4,000 hours, at 8,000 hours, even at 20,000 hours.

They die from different reasons, many of them not related to hours of use.

Does it have good oil pressure? Does it smoke? Does it use oil? Does it have good compression (so starts instantly)? No untoward sounds? Doesn't overheat at redline under load?

If checks out for all for all of that, you might very well get another 24 years out of it, if you take care of it (change oil religiously, avoid harmful regimes, etc.). Or you might not. Old diesels are always a bit of a crapshoot.


I disagree what a lot of what is written above. There is nothing at all wrong with turbodiesels; these actually have a big advantage for sailboats which rarely need full power but sometimes do. That is because for a given full power rating they can be smaller displacement which runs better under low loads. And the turbochargers themselves are very reliable. Diesels and turbos go together like cookies and cream.


The Yanmar turbo JH models, for example, are excellent engines; you will use the 100hp or 120hp under full boost very rarely, and the rest of the time you are using 20hp in a healthy regime since it's only 2000cc; much better than a 4.4 liter Perkins which will not be able to warm up its cylinders using only 20hp. Now if you put one of these in a motorboat and run it wide open all day long, that's a different story, but in a sailboat these are great engines. Half the weight of the Perkins as well.

[MHTinkler]

Diesel powered trucks regularly run over a million miles with just regular oil and filter changes. No reason a boat engine wouldn't last a very long time if treated with the same care. Particularly considering the vastly cleaner conditions marine diesels operate in. The only caveat being that many marine diesels (including on my boat) do not have air filters. This was total hearasy to me, so I added one. I don't think I will regret investing the little time, money and effort it took.

[skipperpete]

One of the reasons that highway truck engines often last so long is that they have bypass lube oil filters, get good quality regular maintenance by mechanics who actually know what they’re doing........ and most importantly, don’t have the destructive wet exhaust system used on marine engines.

[freshalaska]

What are the issues with wet exhaust?

[skipperpete]

Here are just a few pics of some causes of catastrophic failures due to wet exhausts, if you browse this forum you’ll find pages of tales about seized pistons, rusted crankshafts, bent conrods from hydrolocking, ruined turbochargers, corroded cylinder heads and stuck valves.

[sailingharry]

Originally Posted by skipperpete

Here are just a few pics of some causes of catastrophic failures due to wet exhausts, if you browse this forum you’ll find pages of tales about seized pistons, rusted crankshafts, bent conrods from hydrolocking, ruined turbochargers, corroded cylinder heads and stuck valves.

A pretty compelling case for periodically removing and inspecting, or preemptively replacing, the wet exhaust components (heat exchanger and exhaust elbow). Not that that is easy or cheap, or something that isn't easily put off until "next year."