Yanmar 4JH 3E Lifespan

[loowigi]

Apologies if this has been asked before, but if you take the law of averages, what is the life span of a 4JH 3E diesel engine in hours. I know it depends on how it has been looked after, but average? Thanks

[Sabbatical II]

I've just bought one and haven't got it wet yet, so hopefully a real long time.

Greg

[swagman]

Ours is past 2,000 hours and nothings yet gone seriously wrong with it and I'd expect it to last at least 20,000 hours.

But your question is a tricky one for anyone to answer so I relate it to a car diesel engine.

I'd expect one of those to be good for at least 150,000 miles - average speed say 40 mph gets you 37,000 hours.

Knowing the boat engine is working in a harsher environment I'd almost halve that to the 20,000 - and just ensure we exchange oil and filters just as often as we can.............

Cheers
JOHN

[shakey doug]

G'day,

Some local crayfish boats have jh series running freezer compressors that are merrily chugging along with 18000 + hrs in the bag with nothing more than regular servicing.
At trade tech college we where taught 1000 eng hrs = 33,000 miles based on 30 mph.
150,000 miles --- 40mph= 37,000 hrs ??

[loowigi]

Thanks for the feedback, lot more hours than I thought!!!! Was thinking around 10000 would be the time that an overhaul would be necessary.

[FraidNot]

mine is still running like a sewing machine (touch wood) at 5700 hours. Beautiful clean oil and no exhaust colour.

[Dockhead]

Originally Posted by swagman

Ours is past 2,000 hours and nothings yet gone seriously wrong with it and I'd expect it to last at least 20,000 hours.

But your question is a tricky one for anyone to answer so I relate it to a car diesel engine.

I'd expect one of those to be good for at least 150,000 miles - average speed say 40 mph gets you 37,000 hours.

Knowing the boat engine is working in a harsher environment I'd almost halve that to the 20,000 - and just ensure we exchange oil and filters just as often as we can.............

Cheers
JOHN

Umm, 150,000 divided by 40 is 3750, not 37,500.

I can't imagine any car which is used much in town averaging 40 mph over its life. My Range Rover keeps track of cumulative average speed, and at the moment it is 20 km/h (12 mph). Admittedly in a large metropolis.

At 20 mph average speed, 150,000 miles would be 7,500 hours.

At 12 mph (like my RR), 150,000 miles would be 12,500 hours.


If we forget car engines and think about real experience with boat engines, we had a Perkins 4-108 with 10,000 hours on it without major work other than a valve job here and there, and still started and ran very well (leaked oil all over the place, but that's a design feature, as the software guys say).

I think 10,000 hours is pretty old age for a boat engine, especially if it has any complications like turbochargers. But as far as I understand, 5,000 hours ought to be trouble-free for any decent marine diesel.

[djmarchand]

That question was asked of a Mack Boring representative at a cruisers conference. The guy was a real mechanic, not just a rep. He said that they have 4JH engines in some of the water taxis at Annapolis. Admittedly these are used every day and probably get superb maintenance. He said they routinely pass 10,000 hours, some have hit 20,000.

Real world average, I would guess maybe 5-10,000 hours.

David

[Chief Engineer]

I worked on the watertaxis in Baltimore.....The engines held up well with good maintenance.....The reduction gears didn't that was due to the "Captains" spasmodic shifting......AMB (Ain't my boat) Syndrome.

[David M]

Originally Posted by Dimitri

Apologies if this has been asked before, but if you take the law of averages, what is the life span of a 4JH 3E diesel engine in hours. I know it depends on how it has been looked after, but average? Thanks

The life of a diesel engine does not depend so much on its brand and model number. It depends mostly upon how frequently you change the oil and how much it runs at greater loads during its lifetime. The greater the load, the longer it lasts. Running diesels at low loads shortens their lifespan.

[loowigi]

Hi David mentioned brand and model as the boat I am considering has that particular diesel engine powering it. Motor has heavy hours and looks to be quite close to needing an overhaul.

Thanks for your info!

[MitchM]

before making a purchase deicision : 1) ask if the previous owner kept a maintenance log and look at it 2) get repair records for the engine from him 3) get a qualified diesel mechanic to do an engine survey , run some compression tests on the cylinders and go over the turbo and pumps.

some brokers won't let you survey unless there is an offer on the table -- if so make a lowball offer and write 'offer to be withdrawn without penalty if fault costing more than $500$? 1000? _____ is revealed by any surveyor.' FAULT is defined to include lack of recommended maintenance, design fault, installation fault, or component or system nonfunctional or needing replacement or repair due to failure, age or deterioration .' (this language saved us 10K$ when buying our last boat. the airconditioning system installed by the previous owner of our boat had a design fault of not only being 6kBTU undersized for the boat, but also being improperly installed...too small a seacock, insufficient prime to pump, bad AC wiring.. )

by the way engine manufacturers generally recommend service intervals for each engine --usually 50, 100, 300, 500, 1000 hrs, owners should not be waiting for 500 or 1,000 hrs to do service...under the FIWIB 'fix it when it breaks' theory of boat ownership...

[Dockhead]

Originally Posted by David M

The greater the load, the longer it lasts. Running diesels at low loads shortens their lifespan.

I know that this is in accord with the popular wisdom, but I don't believe it. Load and heat = wear. This is elementary for any mechanical system. So the less load, the less wear, and the longer the life, for a diesel engine, just like any other mechanical system.

With diesel engines, at a certain point -- 20% of full power? 10% of full power? -- the trend reverses, because other bad effects come into play. Bores get polished. But it is false logic to deduce from this that "the more the load, the longer the engine will last". No. The less the load, the longer the engine will last, as long as you have at least enough load to keep your bores from getting polished and so forth.

[Hudson Force]

I have 5,000 hrs. on my 4JH3E. I am on my third oil pressure sensor (my only disappointment). I did require a Kanzake transmission rebuild, but that was due to a cable position error. At 4,980 hours I had to replace my oil cooler due to metal fatigue at the water effluent hose barb on the cooler. I've required no other repairs and I've kept to a oil change schedule and run the engine at least one half hour every week. Take care and joy, Aythya crew

[GordMay]

Originally Posted by Dockhead

I know that this is in accord with the popular wisdom, but I don't believe it. Load and heat = wear. This is elementary for any mechanical system. So the less load, the less wear, and the longer the life, for a diesel engine, just like any other mechanical system.

With diesel engines, at a certain point -- 20% of full power? 10% of full power? -- the trend reverses, because other bad effects come into play. Bores get polished. But it is false logic to deduce from this that "the more the load, the longer the engine will last". No. The less the load, the longer the engine will last, as long as you have at least enough load to keep your bores from getting polished and so forth.

Indeed.
The key is to bring the engine up to specified operating temperature.