Lifespan of a Diesel Engine - Page 3 - SailNet Community
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post #21 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

Industrial diesels using pretty much the same motors as found in many boats run somewhere between 8000 and 12000 hours if not longer in some cases. However, these engines tend to run continuously and at constant speeds rather than in the smaller bursts as happens on sail boats. I'd really think that time/corrosion is the killer on a boat engine assuming that water ingress doesn't do it first.
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post #22 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

Here's the way I see it.

If you start with a brand new diesel, maintain it very well and run it properly, you will get substantial life out of it.

However, buying one run by another is a crap shoot. Whether with 500 hrs or 5000 hrs. First, they need to be broken in by running them very hard. That's counter intuitive, so some owner may baby their new motors, which can improperly seat the rings to the piston walls. You can't know. You can't tell how often oil was changed (the smartest thing you can do is change it frequently, even if you don't do the filter).

The good news is, diesels are pretty simply mechanical devices. A good mechanic (although very hard to find) can generally diagnose the current condition of a motor. Compressions, noises, smoking, oil analysis for metal wear (must be done after running at sea for a while), etc. Wear items can be replaced: belts, hoses, exhaust elbows, fuel filters, etc. Cooling passages can be descaled, tanks can be cleaned, etc. What they can't do, is tell you how well it was routinely maintained, therefore, how long it will likely last.

The further problem with diesel surveys is many aren't worth a cent. They visually inspect, fire it up at the slip, run it for 15 mins, take a compression and send you a bill. If you are getting one at all, they need to take a few things off to see inside, such as the elbow for starters.
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post #23 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

Quote:
Originally Posted by Waltthesalt View Post
A big factor in reducing life is not running the diesel at power. Running for short periods and not letting it to get to temperature causes early failures.
I agree. Other than overheating I bet the biggest killer of inboard diesels is "kindness".

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post #24 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

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Originally Posted by Don0190 View Post
I agree. Other than overheating I bet the biggest killer of inboard diesels is "kindness".
Yes, run it often, run it hard, torture it a bit...regular oil changes, clean fuel and she'll run a long long time. Warp speed, Scotty....
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post #25 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

Most industrial 'prime mover' diesel engines are usually selected/operated at ~75% of max. rpm so to obtain maximum service life. The same approx. 75% of max rpm is the design selection on most boat diesels.

Running hard and often for a cast iron marine engine allows a thick internal buildup of 'black' or ferrous rust which is protective. Over time of long term inactivity the black rust will convert to destructive 'red' / ferric rust. So, if shutting down for long periods of time consider to add antifreeze containing anti-rust compounds to preserve that black rust. Draining a cast iron engine for long term layup accelerates the formation of 'red' rust, which may be the severe form of 'red' rust - *SLAB rust* which are huge 'platelets' of red rust which can 'push apart' the natural stratifications in the cast iron casting.
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post #26 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

Mercedes-Benz museum in Germany has 1988 200D with 1.9 million km on the original diesel. Used as a taxi in Portugal. Assuming 50 km/h average, which is probably generous for a taxi, this is 38000 hours.
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post #27 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

The comments suggesting that hard use, full warm up have been echoed by every diesel mechanic I've known.

It is ironic that most sailors use their engines to get in and out of the harbor, in short bursts and not fully warmed up.

Without trying to start an alternate discussion (or fight!), this is a good argument for the good old Atomic 4 gas engine. Gas engines do well the manner many sailor use their auxiliaries - short duration, on/off...which is why their are many 30-40 year old A4s still out their, mine included.

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post #28 of 87 Old 04-08-2015
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Re: Lifespan of a Diesel Engine

Quote:
Originally Posted by Waltthesalt View Post
A big factor in reducing life is not running the diesel at power. Running for short periods and not letting it to get to temperature causes early failures.
Unfortunately the above scenario is an almost perfect use of a sailboat's auxiliary engine...

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post #29 of 87 Old 04-09-2015
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Re: Lifespan of a Diesel Engine

Question for the class: what's considered best practice, considering you are going to run for just a few minutes to get in or out? Let it warm up at idle at the slip till the temp gauge jumps? Warm up at a fast idle? Screaming idle?

Buy a long shaft two-stroke kicker that will take infinite abuse for marina maneuvers and save the diesel for motor passages?
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post #30 of 87 Old 04-09-2015
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Re: Lifespan of a Diesel Engine

I warm up for at least 15 minutes at the slip, to get to temp. Easy to do, while other cast off tasks are underway. Once clear of the harbor, I usually open her up to position myself in the best spot for the first tack. Why not. Good for the motor, less goofing around and off I go.
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