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Sabbatical II 08-04-2013 12:25

Yanmar Engine Life Expectancy?
I have a 75 hp turbocharged Yanmar engine fitted to my yacht built by Bluewater Cruising Yachts in Newcastle. Mine is the 4th such engine they have fitted. Disturbingly, I have found that number 1 engine has recently failed at 500 hours with a glazed bore on all 4 cylinders. It was using 4 litres of oil per hour in the end. The smoke haze was unbelievable and obviously it effectively, "engineless". It began using oil at 200 hours. I know the owner and he is reputably fastidious about maintenance. Yanmar are claiming it is "operator error" and are not playing ball at all. I think they are claiming excessive idling or low speed operation. I know that the particular engine in question was let sit idle in Cairns for 12 months but I can't see this is a factor. Our particular mechanic says we should be running this motor at about 2800 RPM. 3200 RPM is maximum but the motor is very thirsty at this speed. It uses less than half the fuel and runs sweetly at 6 knots at about 2200 RPM. Since I heard of his troubles, for every hour running, I'm giving mine a run a near maximum revs for a few minutes.
My question is; are these motors typically that fragile and am I doing enough?

gonesail 08-04-2013 12:35

Re: Yanmar engine life expectancy?
change the oil every 100 hours or less .. keep fuel filters clean .. run to the RPM where it feels good and smooth .. fix anything that breaks .. get a good visual on the motor as often as possible. mine ran best at around 2400 to 2600. sitting for a year does not sound like a good thing. i did hear you should vary the rpm when underway which is what i did.

Pete7 08-04-2013 12:45

Re: Yanmar engine life expectancy?
Greg, sounds like folk are killing these engines with kindness. You need an Italian tune up - rev the bollicks off it for a hard 10 hour trip at flank speed.

Idling a diesel at the dockside hour after hour is a death sentence and I am not surprised the manufacturer is walking away.

The piston rings are tapered so that under high pressure (lots of revs) they move out and achieve a good seal with the cylinder bore. At low revs the piston rings remain further inside the piston groves and skim over the bores allowing gasses to by pass encouraging engine oil to burn onto the cylinder walls which is then polished to a varnish like consistency. Once this happens it is very difficult to remove this without taking the heads off and re-honing the bores with a cross hatch pattern.

s/v 'Faith' 08-04-2013 12:48

Re: Yanmar engine life expectancy?
Not sure where 100 hour oil changes came from ? I guess if you only day sail....

I have been babying mine, with 200h oil (and filter of course)... Rarely run over 2000 rpm, but always with motor in gear and turning engine driven compressor...

Keep to the factory maintenance schedule and USE the motor. I will let you know, about to do the 1000 hour service on my 4jh.... Seen them at 8k running well.

mcerdos 08-04-2013 12:48

Re: Yanmar engine life expectancy?
With proper maintenance, the engine should exceed 6,000 hours, or more.

They do not like to be run at a constant RPM. If you are on a long trip, in idle or running for more than an hour or so, be sure to vary the RPM and rev the engine occasionally. This is in the operating manual but few boaters adhere to it.

Also, engines do not like to sit for very long between starts. If you are unable to run the engine bi-weekly, consider paying someone to do so.

neilpride 08-04-2013 13:00

Re: Yanmar engine life expectancy?
Yanmars are hig rpm engines, mean that rings , pistons, cilinder bores and all the related moving parts like valves , crank rods etc... take a beat in the long run, with properly oil changes using a good oil, filters etc can run fine for many thousand hours , but dont expect the same life expectancy as a good low rpm hig torque engine in the same circunstances, heat exchangers in yanmars and exaust elbows fail fast due quality, engine mounts same, and are expensive,,,, saying that , Yanmar ok as far you pull the pedal to the metal....:thumb:

cal40john 08-04-2013 13:14

Re: Yanmar engine life expectancy?

My Yanmar GM manual, and a YM manual I've seen both state how the manufacturer wants the engine to be run, particularly when the engine is new to not glaze the cylinder walls.

If the guy admitted that he didn't follow what the manual says to do, why should the warranty apply?

djmarchand 08-04-2013 13:16

Re: Yanmar engine life expectancy?
Here is my take on the subject, distilled from thousands of hours operating a diesel and maybe hundreds of hours reading the boatdiesel web site.

Diesels can glaze cylinders from running too slow. But it takes hundreds of hours of low speed, near idle operation to do it. Glazing occurs (as another poster correctly noted) when there is not enough pressure on the rings to seal them. Oil is sucked up and combustion gasses blow down and unburned diesel accumulates on the cold cylinder walls and forms a polymer like substance on the cylinder walls. When this happens the rings no longer seal at all and high oil consumption occurs.

A quick solution that sometiimes works, is an "italian Tuneup". Run the engine hard, within 200 rpm of top for several hours. The high temps will sometimes burn off the glazing. It can't hurt to try. If this doesn't work, the only sure remedy is to pull the head and pistons and run a hone down the cylinders. So to say the engine is trashed is a bit of hyperbole. It might take a thousand dollars of labor but not a whole new engine.

That engine is rated to produce 75 hp at 3,600 or 3,800 rpm (depends on the model). If you run it at least 2,00o that is enough to keep it up to operating temperatures and provide enough pressure to seal the rings. For extra measure, run it up to wot for 15 minutes every 10 hours of 2,000 rpm cruising to do a mni Italian Tuneup.

That engine will last thousands of hours if operated in the 2,000-3,000 band with proper maintenance.


motion30 08-04-2013 13:19

Re: Yanmar engine life expectancy?
I guess this is why I like the old low tech diesel engines does it seem like you yanmar has more than their fair share of problems. or is the situation is there so many of these engines out here you just hear about the problems more ?

FLLCatsailor 08-04-2013 13:19

Re: Yanmar engine life expectancy?
I've had charter boats with the 75hp yanmar turbo diesel with over 6000 hours on the engine... Yanmars are pretty bullet proof... Obviously you want to make sure you stay up on the maintenance...

Hudson Force 08-04-2013 13:37

Re: Yanmar Engine Life Expectancy?
I'll just toss in my annecdotal data. I have a natuarally aspirated 4JH3E 2001 Yanmar with over 6,000hrs. I change the oil and filters every 200 hrs. and I adjust the valves every 500hrs. This is usually just a check of the valves and not often an adjustment required. I run it at around 2600 and for a minimun of one-half hour a week if I'm not actively cruising. Over these 12 years of use my only failings have been replacing the oil cooler due to a metal fatigue crack at the water fitting and replacing the oil pressure sending unit three times. I have no idea why I can keep this oil pressure unit working for more than about 1700hrs!I'm remaing at 180 degrees F for the cooling water temp and running smooth while looking new! Of course, all this doesn't mean that my engine won't fail at any time!.... but it's putting on a good show!

Pete7 08-04-2013 13:40

Re: Yanmar engine life expectancy?

Originally Posted by FLLCatsailor (Post 1205780)
I've had charter boats with the 75hp yanmar turbo diesel with over 6000 hours on the engine... Yanmars are pretty bullet proof... Obviously you want to make sure you stay up on the maintenance...

Charter boats have a couple of advantages. Engines serviced on time but no more with the right brand of oil, not the latest hyper synthetic racing oil. They are operated by folk who don't care for long warm up times instead want to get going and will crack open the throttle to get to the destination quickly to make the most of their holiday. Finally they are used week in, week out not left for months on end unused. Ideal use for engines which will go on for year after year.

Kenomac 08-04-2013 13:56

Re: Yanmar Engine Life Expectancy?
We killed our Yanmar's turbo at less than 900 hours, likely due to an incompetent mechanic setting the Maxprop to the wrong pitch. Lot's of different circumstances can cause the early demise of a diesel or it's turbo. If well maintained and revved properly the Yanmar should last 8,000-10,000 hours, or so I hear.

Be sure to rev your engine up over 3,000 rpm for five minutes for every hour you run it at 2,000-2,400 rpm... otherwise bad things will happen.

sailorboy1 08-04-2013 15:43

Re: Yanmar Engine Life Expectancy?
People should read their manuals!!!!

You can idle the Yanmar as many hours as you what to. But you need to run it up in rpm every couple of hours LIKE IT SAYS IN THE MANUAL!

Dockhead 08-04-2013 16:28

Re: Yanmar Engine Life Expectancy?
It's important to use the right type of oil. Yanmar specify type CD, which is not even available anymore!!! You need a mineral oil with few additives -- read this: Oil for yacht engines

Synthetic or high performance oil can really cause bore glazing in a marine diesel engine.

I agree with Pete's advice above -- I think marine diesel engines need a certain ration of hard running every certain number of hours. I run mine at redline (3800 RPM) for twenty minutes every week or two. I also like to back down on my anchor at full throttle, which gives the engine a workout too.

If you use your main engine for charging batteries, it's good to put the engine in gear so it has some load.

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