Diesel engine advice

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davecr

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What is the acceptable maximum running hours before a diesel engine should be replaced. I'm looking at purchasing a 30 year boat fitted with an engine with 2850 hours on the clock. Cosmetically the paint on the top cover is flaking off and there is some surface rust. Your views and comments would be most helpful. Thanks.
 
2850 hours is nothing if the engine's been looked after. With regular servicing, marine engines can last for many thousands of hours. However, the problem with older engines is that parts may no longer be available if needed.
 
Typical yacht usage is around 100-150 hours a year so those hours are about right. Difficult to wear an engine out mechanically - life of 8-10000 hours is not unusual. Marine engines die from lack of hard use, long periods of no usage and poor maintenance. Cooling systems and electrics are the most common things that go wrong.

The engine (Volvo 2030) in my last boat did over 3500 hours in 13 years, most of it in the first 8 years as a charter boat and was running as well at the end as it was when new with no major replacements other than an alternator.

What engine is it?
 
A 30 year old engine is always going to be a bit of a lottery, but the one in my last boat was that age and was in excellent health - always started properly and never used any oil.

You want to see the engine start from cold - the block and exhaust manifold should be at ambient temperature; if they're even slightly warm, come back another day or, if the seller insists it is cold, thank him politely for his time and look elsewhere. It should jump into life in the summer; a bit of churning in winter is acceptable for engines that don't have heater plugs, as is a bit of smoke until it warms up, but it should go when warm. The oil pressure should jump up within a second or two. Any longer and I'd be suspicious of wear. You also want to see a good flow of water from the exhaust.

If it passes all those tests, see how it pushes the boat along. When I bought my first boat, it passed appeared fine, but had absolutely no guts. The ability to punch a tide or a lumpy sea and a good breeze is invaluable, and an underpowered boat is a misery in those conditions.
 
My 4-107 Perkins is a mid 50's lump and will see me out long before it gives up.

My engine literally looks like scrap rust lump ... but purrs like a kitten.

Diesel engines are strong workhorses built like proverbial ... on a boat - they rarely get pushed like car / truck engines ...

I would want to see it running and listen / observe it .... I am not so sure of anothers "block and exhaust manifold should be at ambient temperature; if they're even slightly warm, come back another day " ..... mine runs warmer than ambient .. I can still put hand on though.
 
Refueler said:
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I would want to see it running and listen / observe it .... I am not so sure of anothers "block and exhaust manifold should be at ambient temperature; if they're even slightly warm, come back another day " ..... mine runs warmer than ambient .. I can still put hand on though.
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Think he was referring to the engine having been 'warmed up' before he came to look at it. Rather than a start from cold that would show deficiences
 
Mine has done over 4000hrs and has never let me down in 7 years of ownership. The only alteration I have made was a wiring one - the solenoid/wiring connections were such that sometimes upon turning the key, it would just click.I added a relay to the system and now it starts first turn every time.

Don't be too quick to condemn an engine that can't push the boat along fast enough - growth on the hull and the prop can cause a very significant drop in performance.
 
Refueler said:
I am not so sure of anothers "block and exhaust manifold should be at ambient temperature; if they're even slightly warm, come back another day " ..... mine runs warmer than ambient .. I can still put hand on though.
Click to expand...

Stemar specifically said "You want to see the engine start from cold.." which is why he said the engine should feel at ambient temperature. I'm sure yours runs warmer than ambient - most do.
 
Boater Sam said:
Some of the worse engines have only been run for hours on tickover charging batteries, some of the best have been thrashed day after day, Diesels thrive on hard work.
Click to expand...

There's some truth in that statement. Our first full season with the boat we decided to do N Wales to Portugal and back. Just off Viana de Castelo, engine blew all the oil out. Stripped on Monday, found stuck rings in one cylinder and bores like mirrors, fortunately no bearing damage.

Phoned Diamond Diesels for ring and gasket set and first question was - have you been motor sailing or charging batteries a lot at low revs? I hadn't but didn't know about previous owner. Anyway, parts arrived next day by courier, new rings fitted, bores de-glazed and head overhaul, back in and running Friday. Very easy engine to work on.
 
pvb said:
Just shows you need to be careful about the quality of "advice" given on here, as with any forum.
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That said, I think there is a consensus that -
- 2,000 hours is, in itself, nothing at all to worry about. 2,000 hours will not get anywhere near wearing out a diesel engine.
- lack of use and/or regularly running only lightly loaded associated more with problems than hard work and hours
- it is often the peripherals - electrics, cooling, fuel supply - that let down an old engine, and/or lead to it becoming unreliable, rather than the fundamentals of the engine itself
- an older engine can be problematic if common spares are not available for that model, but there are numerous older engines with most spares still readily available (most are marinised versions of industrial and/or vehicle engines)
- an engine that has not been maintained is a worry, but a rusty surface does not necessarily (but could) indicate a lack of care and maintenance
- starting an engine from cold (i.e. ambient temperature) can tell you quite a lot about the condition of an engine if you know what to look/listen for (and as Stemar implies, if the owner wishes to start it from warm while trying to make you think its starting from cold, there are probably engine problems in addition to the problem of the dishonesty of the vendor).
 
As others have mentioned, hours is just one factor to consider, it needs to be balanced with the overall condition.

When I worked at an engine manufacturer (a long time ago now), we used 50mph as a comparative average when comparing marine engine hours to miles on the road. Based on that calculation, 2850 hours equals 142,500 road miles.

The caveat here is that you compare commercial road miles (i.e lorries/trucks), not cars. Marine engines usually need some major work around 5000 hrs (250,000 road miles), which compares well with a big truck engine.

So 2850hrs is a lot, but in and of it's own is not a reason to go one way or another. If you are unsure, with an engine of that age and use I advise employing a marine engineer to attend at the same time as the surveyor to carry out a mechanical inspection.
 
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