How long should an engine last?

[skyflyer]

... on a 30ft sailing yacht where it is seldom used at high revs or for any great length of time. Occasional 15hr + stint at 2500rpm for a passage in calm winds but normally just coming alongside, pootling up and down rivers and so on, ie typically 1500rpm.

Basically the hours meter has just tipped 2000hrs, all seems well, good fuel consumption, (1-1.7 l/hr) occasional top up with oil, no smokey exhaust but cant help wondering when I need to start saving pennies for a replacement.

Diesel, 3 cyl, 28hp Westerbeke 30B. Serviced regularly.

What is a reasonable expectation do you think?

Thanks

 

[Tranona]

The basic engine should be good for 8000 hours. However it is the ancilliary bits that are more likely to fail - exhausts, cooling, electrics long before you get any serious problems with wear of pistons, bearings etc.

HOWEVER, your pattern of usage is the worst you can do to the engine. The 15 hours at 2500 is great - exactly what it is designed to do. The 1500 for short periods at the beginning and end of a passage is not good. You should try to run it at 2500 for enough time to get it up to full working temperature. Typical problems of lots of slow running are coked up exhausts and valves and bore glazing which results in loss of compression and high oil consumption.

 

[skyflyer]

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?

 

[pvb]

The car comparison is apt. Just using a car for an odd half-mile trip to the supermarket will wreck it very quickly, as it doesn't ever get up to a decent working temperature. On the other hand, cars in taxi use 24 hours a day (with multiple drivers) can do huge mileages without serious problems, because everything's operating at optimum temperature.

Just pootling around in and out of moorings, at tickover, as many boatowners do, is very bad for the engine.

 

[Tranona]

Yes, it is typical use in a sailboat, which is why engines typically last only 30 years or so - probably around 2500 hours. The base engines are designed for use in industrial applications such as diggers, refrigeration units, generators, farm machinery etc which often run 8 hours a day, 200+ days a year and last typically 5 years - but are run usually at 70% max power continuously.

There are many engines in charter yachts, particularly things like flotilla lead boats in the Med that run over 10000 hours without problems. Constant running at cruising revs and regular oil and filter changes is the secret.

You can potentially prolong the life of your engine by minimising the amount of short period low speed running - plus of course your regular maintenance..

 

[Tranona]

On the other hand, cars in taxi use 24 hours a day (with multiple drivers) can do huge mileages without serious problems, because everything's operating at optimum temperature.

The airport taxi service firm I used to use thought nothing of 250000 miles on the diesels in Ford Galaxys cruising up and down the motorway 3 or 4 return journeys a day.

 

[PerformanceSailor]

FWIW dept.....
An expert diesel mechanic that I know and allow to work on our boat advises owners of sailboats with small diesels to take them out for what he calls a "smoke run" about once a month. i.e. bring up to full revs under load for about 15 to 20 minutes or a bit more.

He also sez that short trips that do not put much of a load on these emgines and often do not even achieve operating temperature are the worst things you can do to them.

Check your operating manual for "cruising rpm" and be sure that you do run it at level, too.

 

[oceanpilgrim]

as already said,change oil and fillter every year,clean fuel fillters and run hard at times
as its a westerbeke it will do 25000 hrs no problem,mine was fitted in 1976 has been round the globe already had head gasket job in south africa ,pump serviced in florida in 2004,normal alternator,starter motor overhaul 7-8 years

 

[charles_reed]

Small boat engines

10K hours, if reasonably well looked after, would be commonplace.
However most get ignored, are run infrequently and expire due to accident damage by an incompetent engineer.
For most diesels optimum rpm are max torque rpm and if being run at low revs for any time, the engine needs a blast every 60' or so to 75%.

 

[status]

FWIW dept.....
An expert diesel mechanic that I know and allow to work on our boat advises owners of sailboats with small diesels to take them out for what he calls a "smoke run" about once a month. i.e. bring up to full revs under load for about 15 to 20 minutes or a bit more.

Also works with the mother in law's car, I know it as an "Italian tune up"

 

[skyflyer]

all great information, many thanks; however I need to be realistic too - sailors sail (or generally, they prefer to anyway!) so the original question perhaps remains - i.e. given typical useage what is a reasonable life expectation.

By comparison, light aircraft dieses are typically run for a minimum of an hour at a time, usually at a steady 2500rpm, are meticulously maintained and the engine goes back for a major overhaul every 2000 hrs. For this reason group owners (ie shared) generally keep contributing to an 'engine fund' to ensure theres enough in the pot when the time comes to replace or overhaul!

Of course the aircraft model will be built of lighter components to save weight so that explains some of the above, but unless i start offering waterskiing lessons behind the yacht I dont think I'm going to get 10000 hours from it?

Perhaps the better question would be; what will be the first signs that its on the way out - oil consumption, I would imagine?

 

[Salty John]

It seems that, in sailboats, engines of the older, heavier, slower running type such as Perkins 4108 and Westerbekes, last 25 - 30 years and the lighter, higher reving, engines, 10 -15 years.

How many hours the engine runs in this time seems to be irrelevant because it will be massively less than the engine was designed to do in its lifetime.

This conclusion comes from personal experience and through discussing this issue with other owners over many years. A highly regarded diesel mechanic in the USA told me a rough guide is to take the all up weight of the engine and divide it by the consumed horsepower and the answer is engine life (before major overhaul is required) in years. This seems to also suggest that weight is a significant factor in diesel engine life.

 

[Latestarter1]

The basic engine should be good for 8000 hours. However it is the ancilliary bits that are more likely to fail - exhausts, cooling, electrics long before you get any serious problems with wear of pistons, bearings etc.

HOWEVER, your pattern of usage is the worst you can do to the engine. The 15 hours at 2500 is great - exactly what it is designed to do. The 1500 for short periods at the beginning and end of a passage is not good. You should try to run it at 2500 for enough time to get it up to full working temperature. Typical problems of lots of slow running are coked up exhausts and valves and bore glazing which results in loss of compression and high oil consumption.

Good summary. Then marinisation parts which are subject to 'marine age' are most likey to bring a little puddele jumper, or for that matter any marine engine down.

Small Japanese diesel engines came as object lesson to us all, used to British and European junk.

Making ANY comparisons with automotive duty cycles is a complete nonsense. In addition automotive (LDA) engines have a totally different set of design criteria particularly in the area of crankshaft bearing area when compared with Japanese/Korean small industrial engines.

Typically I get asked to sort out problems with small gensets 99% powered with these wee motors. Usually generators are over specc'd leading to light load, 8/10,000 hrs they have excessive blow by. One drawback is that these little engines are not cost effective to overhaul.

Solution is to hire in a load-bank and give the little donk some REAL pain for about five hours. In majority of cases ring pack beds in again and they are ready to rock and roll again often for another 4/5,000 hrs.

How old is the OP? In a properly designed installation base motor will probably out live him in a pleasure application, the marine hang on's will not.

Forget all the 'dock talk' about running motor this way or that, just use it and enjoy it!

 

[skyflyer]

the engine was new in 1995;
It took some 10 years to do 800 hrs before going into shared ownership, so the next 1200hrs has been done in about 7 years.

anyway - sounds like I needn't worry just yet; as usual (tempting as it is to do otherwise) the old adage "if it aint broke, dont fix it" seems to be valid

 

[ex-Gladys]

Be interested in people's observations on mine- Lancing marinised Ford XLD 1.8 Fiesta mill, 700 hours in 16 years, max speed achieved at about 2/3 max revs (2100 out cf 3300). So it is an automotive engine and it does a run to the shops with the occasional motorway trip

 

[Tranona]

It seems that, in sailboats, engines of the older, heavier, slower running type such as Perkins 4108 and Westerbekes, last 25 - 30 years and the lighter, higher reving, engines, 10 -15 years.

How many hours the engine runs in this time seems to be irrelevant because it will be massively less than the engine was designed to do in its lifetime.

This conclusion comes from personal experience and through discussing this issue with other owners over many years. A highly regarded diesel mechanic in the USA told me a rough guide is to take the all up weight of the engine and divide it by the consumed horsepower and the answer is engine life (before major overhaul is required) in years. This seems to also suggest that weight is a significant factor in diesel engine life.

Not sure that is correct. The Perkins 4 108 is a high speed engine - in some applications it will rev to 4000. Small high speed engines did not really arrive until 1980s (Yanmars and small Volvos) and many of those are still running.

If you look at the engines that need replacement now they are typically the older, slower running heavy engines such as the popular Volvos (pre 2000 series). However, they do not typically wear out, but being seawater cooled they suffer from long term corrosion and cooling problems. They are also often killed off by high spares prices because they were low volume specialist products and out of production for 30 years or more.

The newer type engines, mostly Japanese industrial units are far better made (as Latestarter says) than any earlier so called marine engines and being freshwater cooled will outlast them. However, there is the universal caveat about neglect and in newer engines it is the heat exchanger and water pump and exhausts that are the weak points. Also the engines are not easy to rebuild so failure is more likjely to result in scrap engines. However, as already noted, proper use and maintenance should ensure they achieve their design life - which for a typical sailboat is about 50 years usage!

 

[Latestarter1]

It seems that, in sailboats, engines of the older, heavier, slower running type such as Perkins 4108 and Westerbekes, last 25 - 30 years and the lighter, higher reving, engines, 10 -15 years.

How many hours the engine runs in this time seems to be irrelevant because it will be massively less than the engine was designed to do in its lifetime.

This conclusion comes from personal experience and through discussing this issue with other owners over many years. A highly regarded diesel mechanic in the USA told me a rough guide is to take the all up weight of the engine and divide it by the consumed horsepower and the answer is engine life (before major overhaul is required) in years. This seems to also suggest that weight is a significant factor in diesel engine life.

More anecdotal 'dock talk'. Certainly no data to support the fact that older stuff lasts longer than modern designs.

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. Diesel mechanics are certainly not the people to comment about durability and almost bizarre that in the US the Westerbeke which was a part marinised Perkins 4.107/108 had a dreadful reputation for reliability due to simple design clangers made by Westerbeke in the marinisation. Litigation eventually forced the Perkins Westerbeke off the market...........

Took the Japanese to teach Perkins how to design a reliable leak free rear main oil seal!

 

[Latestarter1]

Not sure that is correct. The Perkins 4 108 is a high speed engine - in some applications it will rev to 4000. Small high speed engines did not really arrive until 1980s (Yanmars and small Volvos) and many of those are still running.

If you look at the engines that need replacement now they are typically the older, slower running heavy engines such as the popular Volvos (pre 2000 series). However, they do not typically wear out, but being seawater cooled they suffer from long term corrosion and cooling problems. They are also often killed off by high spares prices because they were low volume specialist products and out of production for 30 years or more.

The newer type engines, mostly Japanese industrial units are far better made (as Latestarter says) than any earlier so called marine engines and being freshwater cooled will outlast them. However, there is the universal caveat about neglect and in newer engines it is the heat exchanger and water pump and exhausts that are the weak points. Also the engines are not easy to rebuild so failure is more likjely to result in scrap engines. However, as already noted, proper use and maintenance should ensure they achieve their design life - which for a typical sailboat is about 50 years usage!

Oops looks like we are in violent agreement!

 

[GrahamM376]

10K hours, if reasonably well looked after, would be commonplace.
However most get ignored, are run infrequently and expire due to accident damage by an incompetent engineer.
For most diesels optimum rpm are max torque rpm and if being run at low revs for any time, the engine needs a blast every 60' or so to 75%.

Not long after we bought this boat, the engine blew all the oil out, rings had stuck in no.2 so massive crankcase compression.

When I contacted Diamond Diesels (Mitsubishi engine) for a ring set and gaskets the immediate comment was "been motor sailing a lot?" Advice was not to run below 1500 revs and regularly give it a good blast out with the throttle on the stop.

Low revs and very short runnning periods are one way to knacker a boat engine and running off load to charge batteries is another.

 

[davidej]

An expert diesel mechanic that I know and allow to work on our boat advises owners of sailboats with small diesels to take them out for what he calls a "smoke run" about once a month. i.e. bring up to full revs under load for about 15 to 20 minutes or a bit more.

I've heard it called 'an Italian tune-up'

A rather amusing name