Determining 'health' of potential new boat's engine ashore.

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fredrussell

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I'm currently thinking of upsizing and have found a boat that ticks most of the boxes for me. Main drawback is that it has its original Yanmar 3GM 27hp raw water cooled engine. It is described as running well and regularly serviced. Its a 30 year old boat/engine, and the way the rest of the boat has been maintained I have no reason to doubt that the engine has been looked after and serviced as it should be. There is no hours meter on the engine unfortunately.

Is it possible for an engineer to do some tests and determine how much life is left in the old donk? I'm thinking compression tests and oil analysis and the like. The current owner would I think be fine with the engine run up ashore by an engineer (with coolant feed seen to obviously).

Is it cost effective to home-refurbish these engines? I rebuilt classic car engines professionally not too long ago so have the tools and ability I feel, but does the cost of parts make this a fools errand?
 
before I bought mine (Nanni 375 ) I had a chat with the shipyard where it was serviced, they were very happy to verify the advertised condition. I also downloaded the Workshop Manual and user manual prior to viewing. Certainly the maintenance is not too onerous, and with the benefit of a workshop manual you obviously have the skills. My engine is a 3 Cylinder Kubota plant engine, spares are easy to get, I needed a new starter motor which in France I was quoted over 500€, but sourced one on UK ebay for 130£.
I'm sure if you search you ll find out lots about your Yanmar, if you can download the manual do a search for spares, then maybe think about calling in a diesel engineer.
I also put a retraction clause that the engine must be seen to Start and Run when on the water

Good luck !
 
The raw water 3gm30s are still good engines. The problems often associated are with salt(calcium/magnesium) deposits in the head. The symptoms are steam in the exhaust (not smoke). Easily cured by a vinegar or Rydlime flush (to-from a bucket under the exhaust). Is the oil clean? what is the service record looking like? assume 100 Hours per year? Running from and to a bucket in the yard for a short while, (out of gear!) is perfectly feasible, with care.
Is the owner amenable?
 
There's a very limited amount you can do with an engine ashore, other than seeing if it starts easily. A diesel mechanic won't be able to add much except for a compression test, which won't reveal much more than seeing how easily the engine starts. Equally, oil analysis won't reveal much if the engine has been given a fairly recent oil change. Oil analysis is likely to be more useful in a larger, more stressed motorboat engine anyhow, not a sailboat auxiliary motor.
I'd save my money, make sure it starts easily ashore and then give it a good work out as part of the sea trial, which should form part of the purchase process. (Offer, survey, sea trial, fault rectification/price adjustment if required, completion.)
 
Thanks guys, the sea trial thing hadn't occurred to me - I'll contact the broker tomorrow and see if owner is happy with that.
 
I think the broker may want a deposit before a sea trial and I don't think I'd be too keen on anyone doing compression test on a boat of mine without first paying a deposit. 3 injectors to remove and reseat without creating leaks isn't always easy.
 
fredrussell said:
Thanks guys, the sea trial thing hadn't occurred to me - I'll contact the broker tomorrow and see if owner is happy with that.
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Remember that a sea trial is a proper 'conducted activity' with a list of things to do, conditions to meet and a pass/fail criteria. It isn't just a 'buzz around the harbour' and 30 minute sail to see what it feels like.

To justify the sea trial you will need to state why you want it and list the items that will be trialled during the activity. Also, expect to pay someone to be aboard and also the owner for use of the boat.
 
It's an old engine.
It may be fine, it may be on its last legs, it's probably 'a bit worn but still goes OK'.
Your sea trial will probably be inconclusive.
You may get results like, it's mostly fine but smokes a little bit flat out.
Your sea trial will cost hundreds.
Even running the motor ashore will cost you for de-winterising and re-winterising?

Even if the engine passes your sea trial with flying colours, it's still an old engine that might curl its toes up in 3, 5 or 7... years.

So if I were buying this boat, I would be taking the view that a new engine might be needed while I own the boat.
Maybe take the view that in say 5 years time, either the boat isgoing to be reduced in value because the engine will then be even more tired, or you will have spent a few grand on a new engine, and the value of the boat will be enhanced by some fraction of that.
At the end of the day, boat engines are a wasting asset.

As for can you rebuild/refurb it?
Yes you can, but IMHO a 're&&&&ed' old engine is still just an old engine. So the best you will get out of that is the engine keeps working while you own the boat, but come time to sell, buyers should just see a vintage motor that runs and will be in the same position you are now. You could have it apart and either spend thousands on it, or just give it a decoke and new rings and it would be improved at sensible cost. Either way, it will still be an old engine.

So maybe I'd guess the cost of that sea trial and put that money into a (virtual) little pot called 'new engine fund'.
But maybe your plans for next year are not compatible with not knowing exactly where you stand with the engine?
 
A couple of things to check: Oil leaks at the flywheel housing which is indicative of the main bearing oil seal failing, the external oil feed pipe behind the starter motor check for corrosion and leaks, crankcase breather, if it's blocked it will inevitably lead to the rear oil seal failure.
Oil analysis is a waste of time although it might show significant metal but it is something that is done periodically and the results and trends analysed. The oil is likely to be new and clean anyway although it will appear black. Is the engine bay, bilge and engine reasonably clean if it is dirty and showing signs visual and odour of old oil then it is a sign of lack of attention.
Spares for Yanmars and Volvos for that matter are notoriously expensive and by the time you have finished rebuilding you will be well on the way to a new engine in price.
A sea trial is the way to go which is going to cost you the lift in and out fee, if it starts easy there is no smoke under full load and it doesn't overheat it should be OK.
A lot will depend on how the engine has been used and for how long but at 30 years old it is going to have 3000 Hrs plus on it and the usual service life quoted is 5000 Hrs. Think about a diesel engine in a car doing 60 mph for 5000 Hrs = 300,000 miles, sounds about right.
A re-engine with all the other bits which if you are doing it could cost north of £6K so if you are going to keep the boat for any length of time then you may well have to fork out that amount at some time in the future so best factor that in in your annual running costs.
Finally with a 30 year old boat the age and condition of the engine should have been factored into the selling price, you know what it is and if it starts and runs OK without exhibiting the obvious faults then that is what it is a 30 year old engine in a 30 year old boat.
 
Fr J Hackett said:
A couple of things to check: Oil leaks at the flywheel housing which is indicative of the main bearing oil seal failing, the external oil feed pipe behind the starter motor check for corrosion and leaks, crankcase breather, if it's blocked it will inevitably lead to the rear oil seal failure.
Oil analysis is a waste of time although it might show significant metal but it is something that is done periodically and the results and trends analysed. The oil is likely to be new and clean anyway although it will appear black. Is the engine bay, bilge and engine reasonably clean if it is dirty and showing signs visual and odour of old oil then it is a sign of lack of attention.
Spares for Yanmars and Volvos for that matter are notoriously expensive and by the time you have finished rebuilding you will be well on the way to a new engine in price.
A sea trial is the way to go which is going to cost you the lift in and out fee, if it starts easy there is no smoke under full load and it doesn't overheat it should be OK.
A lot will depend on how the engine has been used and for how long but at 30 years old it is going to have 3000 Hrs plus on it and the usual service life quoted is 5000 Hrs. Think about a diesel engine in a car doing 60 mph for 5000 Hrs = 300,000 miles, sounds about right.
A re-engine with all the other bits which if you are doing it could cost north of £6K so if you are going to keep the boat for any length of time then you may well have to fork out that amount at some time in the future so best factor that in in your annual running costs.
Finally with a 30 year old boat the age and condition of the engine should have been factored into the selling price, you know what it is and if it starts and runs OK without exhibiting the obvious faults then that is what it is a 30 year old engine in a 30 year old boat.
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In principle, all true: except the comparison with a car. My 2.5 litre diesel car revs to 5,000, and develops 215 hp, or 86 hp per litre. My approx one litre boat engine revs to 3,400 and develops 27 hp, an awful lot lower wear and stress. And few cars average 60 mph over their life, except for the almost now extinct motorway repmobile. 30 is more like it. My last same model car engine was fine at 193,000 miles until a valve stem broke, on stripping the engine the bores were near perfect, according to the diesel mechanic who bought the dead car from me after I'd bought another similar one.
 
jwilson said:
In principle, all true: except the comparison with a car. My 2.5 litre diesel car revs to 5,000, and develops 215 hp, or 86 hp per litre. My approx one litre boat engine revs to 3,400 and develops 27 hp, an awful lot lower wear and stress. And few cars average 60 mph over their life, except for the almost now extinct motorway repmobile. 30 is more like it. My last same model car engine was fine at 193,000 miles until a valve stem broke, on stripping the engine the bores were near perfect, according to the diesel mechanic who bought the dead car from me after I'd bought another similar one.
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If your car is anything like mine, it spends most of its time very much below peak rpm.
My 2 litre car averages about 45mpg and 40-45mph, so it's burning similar litres per cylinder capacity per hour, so the stress it's under might be remarkably similar most of the time.
Big difference might be that my car has done its 3,000 hours on well specified synthetic oil.

A boat engine might run a few dozen hours per year, or many hundreds. It might be a lucky one or a lemon.
After 30 years it could be good for another 20 years of careful use or it could be just about to fail horribly.
But then a ten year old motor might be the same, just the odds are a little different?

I guess if one does 'sea trial' an engine and it blows up under full throttle the vendor might be justifiably upset.
 
PCUK said:
If it starts readily from cold (feel the block before starting!) and doesn't smoke, has good oil pressure and no nasty rattles then it's going to be OK.
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I'd agree with this, rough and ready but as long as the engine is fairly clean, as good as anything on an old vessel.

If you are intending to keep the boat for the long term you will end up changing the motor at some stage so boat condition and price is much more important.
Fear the worst if the owner has a sheaf of pretty non-specific invoices for work done.
 
duncan99210 said:
There's a very limited amount you can do with an engine ashore, other than seeing if it starts easily. A diesel mechanic won't be able to add much except for a compression test, which won't reveal much more than seeing how easily the engine starts. Equally, oil analysis won't reveal much if the engine has been given a fairly recent oil change. Oil analysis is likely to be more useful in a larger, more stressed motorboat engine anyhow, not a sailboat auxiliary motor.
I'd save my money, make sure it starts easily ashore and then give it a good work out as part of the sea trial, which should form part of the purchase process. (Offer, survey, sea trial, fault rectification/price adjustment if required, completion.)
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I remember reading previously that oil analysis is only useful if there's a history of previous oil analyses for comparison - that a single test on its own won't tell you much unless there are iron filings in it!
 
You could spend a lot of money on experts doing tests on the engine, possibly a significant % of what the engine is worth. Id be satisfied with the basics---Does it start and run? Does it make noises it shouldn't? Does anything leak from it where it shouldn't?
If it passes those tests then budget accordingly on your purchase price. If it fails those test budget even more accordingly.
 
AntarcticPilot said:
I remember reading previously that oil analysis is only useful if there's a history of previous oil analyses for comparison - that a single test on its own won't tell you much unless there are iron filings in it!
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Yes, very true. I have some experience of oil analysis. It is a useful technique when used as a regular monitoring method for industrial engines but as a spot check it is close to useless. I was involved in the failure diagnosis of some large diesel engines used by a bank to power many ATMs in the Netherlands. Oil was sampled on a regular basis but this bore absolutely no relationship to oil changes, so sometimes the oil sampled had barely done one hour, whereas other engines had completed 4000 hours. One engine ran its big-end bearings in a big way, although the oil analysis said it was perfectly OK.
 
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