How long should an engine last?

Latestarter1 said:
More anecdotal 'dock talk'.

Lower revving argument certainly holds no water, Perkins 4.108 had a maximum rated speed of 4,000 rpm in pleasure applications, most if not all Japanese industrial motors are 3,600 rpm.
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The 4.108 in sailboat applications most usually runs around 2,500 rpm where it generates around 35HP and has a lot of torque. Mine lasted 27 years, many are much older, I'm sure some fail before their time.
I replaced a knackered Yanmar 3GM20F that was 13 years old but I'm sure many last longer.

Hard data is difficult to come by; anecdotal 'dock talk' can be interesting and entertaining and, surprisingly often, it turns out to be true.
 
There were a lot of 4-99/108 and BMC engines around because they were the smallest automotive units to be had 40/50 years ago the alternative being the marine units ie sabb bukh and Volvo which resulted in big hp gains with little on no weight space gain.
As latestarter says the boatyard bits gave up first often causing consequential damage to the base engine.
The marinised engines could be replaced or repaired cheaply as they were mass produced for a market that would not support higher priced spares and yes the automotive units leaked oil which did not matter as it dropped onto the road not into bilges.
None of the " marine " engine makers ever offered a short engine which would have made refurbishment an economical option.
I spent many years trying to convince one manufacturer that a person who decided not to rebuild an engine because of the price of spares would be the last person to buy a new one even if the new unit spare were much cheaper and that they should write off the built in inflation of spare parts which caused the prices to escalate .
BMW did this with car parts with older parts being discounting allowing their cars to be run for longer as the owner profile lowered .
 
Salty John said:
The 4.108 in sailboat applications most usually runs around 2,500 rpm where it generates around 35HP and has a lot of torque. Mine lasted 27 years, many are much older, I'm sure some fail before their time.
I replaced a knackered Yanmar 3GM20F that was 13 years old but I'm sure many last longer.

Hard data is difficult to come by; anecdotal 'dock talk' can be interesting and entertaining and, surprisingly often, it turns out to be true.
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4.99 and 1.5 BMC's they were all new when I was young and seemed cutting edge. Then I was introduced to the Mercedes OM 636 an altogether better class of old motor in the similar displacement node.

Your long lived 4.108 would have been the 3,000 rpm rating and propped to operate at 2,500 rpm was living around peak torque and making a lot of soot in the lube oil, requiring frequent lube servicing.

The advent of flotilla holidays led people to look seriously at yacht machinery and Yanmar won hands down in demanding duty cycles.

Doubt if our 'knackered' Yanmar was failure of the base engine. UK MOD and BAE systems have almost unreasonable preference for Yanmar based on hard data. Personally I favour Kubota. Volvo gave up on thump thump engines years ago switching to the Perkins Shibura.

In the US Yanmar pretty much own the puddle jumper market and Universal and Westerbeke had to get real. For example the three jug Westerbeke referred to by the OP is a Mitsubishi K Series base motor.

My warm feelings about BMC Perkins and even the OM 636 evaporated in the 1980's when I started to encounter the nice reliable AND LEAK FREE japanese stuff.
 
A few years back I was chatting to a marine deisel mechanic with around 30/35 years experience. He said he'd never ever seen a dead marine diesel engine (used for propulsion) that was worn out - they'd all died through other causes as discussed above.
 
My warm feelings about BMC Perkins and even the OM 636 evaporated in the 1980's [/QUOTE]

that was the oil leaks that gave you the warm feelings!
 
I think decently looked after most older engines can be almost indestructable. My first car in 1963 was a 1928 Austin 12/4 which did sterling service for me as daily transport till I joined up, the car was then laid up but resurected some years later and I believe is still running. Most slower running old engines should go on for ever if given decent maintainance, they were in general over engineered and designed to be renovated more than once in their lives
 
Hi all,
Old engineers rule for diesels: 3/4 load 3/4 revs or more at all times = 5000 hours.
Full load / full rated continuous revs = 6000 hours (20% more)
Low load / low revs ( half or less)= constant rebuilds. 1000hrs? 500 hrs? less?
Diesels are high compression heat engines. The higher the load the more they like it.
Proven over thousands of hours on plant machinery.
 
Aw c'mon the classic 4.108 has a rope type of oil seal as did a great many automotive engines of that era. "Why?" you may ask. Well its fairly simple, asbestos rope can stand up to the heat produced by drivers slipping the clutch. Nowadays most automotive engines have a heat-resistant rubber seal that isn't even rubber. Its a fluoro-elastomer which can allegedly be dangerous if burnt and hosed-down. The problem is that small traces of HF (Hydrofluoric acid) can be produced which can ruin your whole day! In England there are companies that will modify the 4.108 so that a modern seal can be fitted. Unfortunately if such a seal leaks it cannot be fixed from underneath as its an engine-out job as the flywheel needs to be removed. Incidentally the Japanese engines are by no means Rolls-Royce as often on the small raw-water-cooled models the heads rust through. At this point they can be stripped of any useful parts then used as a door-stop. On the other hand an old colleague nicknamed "Captain Bligh" told me about a friend of his who is still running a seventy year old Bolinders engine in his fishing boat. They just don't make 'em like they used to!
 
Times have changed and oils and fuels have changed. For example motor insurance policies in the "good old days" often included moped cover. This was so that the car owner could ride his moped in the summer during the annual de-coke. Talking of coke (the carbon type, not the type sniffed by bankers!) an engineer where I worked in the 1960s had a Standard Ten motor car which he had bought new. He nursed that car which by all accounts had never been run at over forty miles per hour. One day he arrived at work by bus, "What's happened to the car?" people asked. "Its broken down" he said "the engine is all clogged-up with carbon." Decades later the problem was still around on the Rover 2600s which were infamous for getting clogged with black sludge and allegedly this is still an enormous problem for high-end Italian sports cars which can never be run fast enough on public roads. Possibly a High Detergent oil intended for diesel engines would be a better lubricant?

Incidentally I have witnessed "black butter" in the sump of a Perkins 4.108 engine that was still in running order. Presumably "boundary lubrication" lasted long enough for the black-butter to melt and work like oil!

As to engine durability, the six cylinder Triumph 2000 engine had a block cast from Chromalloy. This resulted in superb durability to the extent that one engine would probably outlast several body-shells. Unfortunately such engines cannot be retro-fitted into poor quality cars that have modern basket-case engines as emissions laws won't allow it.

Incidentally how much pollution is caused by having to constantly replace poor quality items that have a pathetically short lifespan?
 
QUOTE=rustybarge;3692819]Hi all,
Old engineers rule for diesels: 3/4 load 3/4 revs or more at all times = 5000 hours.
Full load / full rated continuous revs = 6000 hours (20% more)
Low load / low revs ( half or less)= constant rebuilds. 1000hrs? 500 hrs? less?
Diesels are high compression heat engines. The higher the load the more they like it.
Proven over thousands of hours on plant machinery.[/QUOTE]

Hmm I'm not so sure. I used to work at a transmitter station that had six 500 KVA diesel generator sets. The marine style engines produced 750 BHP at 300 rpm but they were troublesome. The lubricating oil was cheap recycled stuff (several forty gallon barrels were needed so GTX was out!) and the big-end shells appeared to be white metal but they were quite large. Before starting we would pump-up the oil gallery by hand with a semi-rotary hand-pump. Eight psi had to be maintained for at least ten seconds before applying the 300 psi starting air. The crank and flywheel assembly weighed twelve tons but the air would twirl it around effortlessly. Another station had diesels that had huge electric starters like car starters but bigger. These were next to useless as the pinions were always wearing out. I suspect that those engines were meant to be decompressed before starting as allegedly the bills for new starter motors were phenomenal! A third station had its diesels clap-out owing to lazy staff not pumping up the lubricating oil before applying the air. Several of our engineers were absolutely outraged and said that the repair bills should have been docked from the salaries of the lazy staff! Three of our diesels were by English Electric and were of course truly brilliant, the other three were not so good and one had a piston seizure which tore-off the big end cap. On the next turn of the engine the crankshaft smashed the con-rod through the side of the block. Oops, good job no-one was standing there!

It did seem that whatever English Electric built would be absolutely top class. One example being the English Electric Lightning which at the time was the only fighter that could catch up and overtake Concorde!

The big diesels in the power station at a British owned location were truly disastrous as after a while the engine blocks failed. Allegedly the engine blocks and their feet parted company leaving large holes in the crankcases. Allegedly the foreign suppliers of the engines paid a huge bung of hush-money so that the customer could pay to get the blocks repaired. Personally I would have advised vibration dampers as well as its odds-on that resonance effects were occurring. Rubber and a heavy mass will damp resonances but the rubber may need replacing from time to time.
In short diesels, even big ones, do go wrong. Small ones go wrong more often but often this is caused by abuse such as driving in 5th gear at 20 mph in the quest to save fuel. IMHO wet exhausts kill more marine diesels than anything else as whilst a diesel car engine will start OK after years of idleness a marine diesel probably won't. The difference is what is in the silencer!

Other thoughts are that marine gearboxes usually shred long before the engine wears out. Take a Thermo-King engine designed to run a fridge for 10,000 hours. Curiously an identical engine for marine use is "Pleasure Rating Only 750 hours maximum per year" (13.33 years to reach 10,000 hours)

Blue Water Cruising is NOT IMHO "pleasure use" as its more akin to industrial 24/7 use. Commercial fishing is not pleasure use either and small gearboxes will fail prematurely.
 
skyflyer said:
Yes i realise its like only ever taking the car to the local shop and back, but probably fairly typical, nevertheless, for a sailboat?

8000 sounds a lot - i was doing rough comparison with a car doing 2000 rpm, say 50mph, that is 400,000 miles?
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Most cars average 25-30 mph overall, lots of near tickover in slow traffic balanced by high speed bits. So 2000 hours = 25-30K miles, at which point a car diesel will be just approaching nicely run in, and unless you wreck it by loads of very short runs and few oilchanges should be good for at least 150-200K miles. That more or less corresponds to the 8,000 hours often quoted as the design life of yacht diesels. Most though get replaced long before then, because owners wreck them by underuse.
 
You can't really change your type of use to suit the engine. So the argument is pointless.
jwilson said:
Most cars average 25-30 mph overall, lots of near tickover in slow traffic balanced by high speed bits. So 2000 hours = 25-30K miles, at which point a car diesel will be just approaching nicely run in, and unless you wreck it by loads of very short runs and few oilchanges should be good for at least 150-200K miles. That more or less corresponds to the 8,000 hours often quoted as the design life of yacht diesels. Most though get replaced long before then, because owners wreck them by underuse.
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As said modern diesels have a life of 8,000 hours. Engines such as the Volvo MD series had no design life. I asked Volvo what it wold cost to build a modern engine to MD standards - £16,000 and that was about 10 years ago.
 
davey said:
In England there are companies that will modify the 4.108 so that a modern seal can be fitted. Unfortunately if such a seal leaks it cannot be fixed from underneath as its an engine-out job as the flywheel needs to be removed.
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Surely to change the old rope-type crankshaft oil seal you had to remove the crankshaft as the upper half was behnd/above it in a groove in the end main bearing housing - that was certainly the case with my MD21B. To change a modern crankshaft oil seal in a boat installation would be much easier; gearbox out, bellhousing and flywheel off and there you go.
 
prv said:
Doubly so when it all happened four years ago until some Cornish insomniac dredged it back up :p

Pete
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Are we really going to go through all this again? :ambivalence:

("Engines have a pre-destined life" threads are like "the anchor chain does the work" threads ...... after the umpteenth repeat you just want to crawl away and die :( )

Richard
 
KellysEye said:
As said modern diesels have a life of 8,000 hours. Engines such as the Volvo MD series had no design life. I asked Volvo what it wold cost to build a modern engine to MD standards - £16,000 and that was about 10 years ago.
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Another piece of useless claptrap. The "MD" series of Volvo engines covers all the Marine Diesel range up until 2005 - including the tens of thousands of Peterborough and Japanese built Perkins based engines which will outlast most of the old clunkers you admire so much.
 
I've been dismantling an old Volvo Penta for spares recently and can vouch for the fact that they were solidly built. The single cylinder model only produced 8hp but weighs a ton. Most of the components are still in useable condition and the crank assembly is extremely robust. The thing that killed this particular lump was that at some time it has frozen up resulting in the water jacket and the exhaust mixer have split.
 
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