robmcg
Well-known member
What are the weak points on the Bukh dv36 engine? Are there any known weaknesses? Would the freshwater cooling conversion have helped with longevity? Anything I should look closely at?
Cheers
Rob
Cheers
Rob
Bukh dv36 what to look out for?
- Thread starter robmcg
- Start date
KenMcCulloch
New member
We (syndicate) bought our boat with a 30 year old indirect cooled DV36 just over a year ago. The advice we were given at the time suggested that yes, the freshwater cooling does contribute a lot to the longevity of these engines. Since taking over the boat the only engine problems we have had have been;
1) Shaft coupling bolts falling out/ shearing. Not a problem related to Bukh-ness.
2) Exhaust waterlock leaking. This was a 30 year old S/S fabrication, again nothing to do with Bukh. We had a temporary repair done and a new GRP waterlock and exhaust hose are going in this winter.
3) Starter intermittently failing to engage. I think that's the kind of thing that happens to all starters on 30 year old engines. It's at the menders and is not expected to cost a lot to fix.
4) We have recently detected a minor coolant leak. Again not a huge problem and relatively easily fixed.
In summary I would have no qualms about setting off on a long voyage with this engine provided it had been recently serviced and such minor problems as noted above, fixed. These engines are approved for installation in ship's lifeboats, a recommendation that must carry some sort of weight I think.
1) Shaft coupling bolts falling out/ shearing. Not a problem related to Bukh-ness.
2) Exhaust waterlock leaking. This was a 30 year old S/S fabrication, again nothing to do with Bukh. We had a temporary repair done and a new GRP waterlock and exhaust hose are going in this winter.
3) Starter intermittently failing to engage. I think that's the kind of thing that happens to all starters on 30 year old engines. It's at the menders and is not expected to cost a lot to fix.
4) We have recently detected a minor coolant leak. Again not a huge problem and relatively easily fixed.
In summary I would have no qualms about setting off on a long voyage with this engine provided it had been recently serviced and such minor problems as noted above, fixed. These engines are approved for installation in ship's lifeboats, a recommendation that must carry some sort of weight I think.
robmcg
Well-known member
Thanks for the vote of confidence Ken. I am sure I have sailed past Cherry Ripe on the Clyde. Are you based up there?
jerrytug
N/A
This is hearsay,worth checking though: The fresh water circulating pump seals can leak,allowing coolant to leak INTO the engine,contaminating the oil. Apparently not visible from outside,double check for mayo!
KenMcCulloch
New member
I think that's definitely hearsay. The freshwater circulation pump is external, driven off the back of the seawater pump and it's hard to see how even a catastrophic seal failure would let coolant into the crankcase. Perhaps a different engine.
Apart from a year or so in the Caribbean a decade ago she has been in and around the Clyde for a long time. We have had her on the East Coast (of Scotland) this year and she is going to the west, near Oban, next season.
LittleSister
Well-known member
Yes, about 628lbs!
p.s. We have a baby Bukh (10hp) - a mere 353lbs (+ freshwater pump and heat exchanger)!
LittleSister
Well-known member
Yes. The issue Jerrytug refers to relates to the DV 10 and DV20. It's a very different pump arrangement on the DV24, 29, 32, 36 and 48.
KINGFISHER 8
Well-known member
....... a Beta! ... :encouragement:
Ashley W
New member
I think these engines are basically sound and long lasting. However from personal experience watch out for:
Freshwater pump, the impeller not rotating with the shaft causing overheating under load.
Rawwater pump leaking saltwater onto steel oil cooler pipe,corroded right through and leaked. Found when oil pressure siren came on because of no oil in sump.
Same rawwater pump leak sprayed saltwater onto engine block and corroded through crankcase, again found by oil leak. Found oil in bilge and eventually found the problem hiding behind pipework and raw water pump. With hindseight the rawater pulp had probably been leaking for ages, possibly years but due to the automatic bilgepump doing it's stuff in the background, visual access virtually zero and obviously it only leaked when the engine was running I was not aware. On the upside the raw water pump can be overhauled very cheaply using bearings and lip seals from an industrial outlet. Take the precaution of specifying stainless springs in the lip seals, couple of extra quid each. Moral of the tale is for the sake of £25 worth of bearing and seals overhaul the rawwater pump before it's an issue!
Freshwater pump, the impeller not rotating with the shaft causing overheating under load.
Rawwater pump leaking saltwater onto steel oil cooler pipe,corroded right through and leaked. Found when oil pressure siren came on because of no oil in sump.
Same rawwater pump leak sprayed saltwater onto engine block and corroded through crankcase, again found by oil leak. Found oil in bilge and eventually found the problem hiding behind pipework and raw water pump. With hindseight the rawater pulp had probably been leaking for ages, possibly years but due to the automatic bilgepump doing it's stuff in the background, visual access virtually zero and obviously it only leaked when the engine was running I was not aware. On the upside the raw water pump can be overhauled very cheaply using bearings and lip seals from an industrial outlet. Take the precaution of specifying stainless springs in the lip seals, couple of extra quid each. Moral of the tale is for the sake of £25 worth of bearing and seals overhaul the rawwater pump before it's an issue!
TNLI
Active member
Thinking of buying a fully overhauled and serviced DV36 RME, with keel cooling as standard. I've noted the points about fitting top quality circulating pump parts, but would be very interested in any other weeak points. Also does anyone know how good the standard gearbox is in terms of output bearing issues. It does use hydraulic fluid, BUT I get the impression it's a simple manual box like the Yanmar 2GM. So if that is the case, has anyone had any problems with gearbox bearing or seal failures ??
Thinking of fitting a 12v prop shaft generator if the gearbox bearing is a tough one, so I also need to know if the gearbox output bearing is a tough one, or easy to change. Finally any opinions about how good Marine Enterprises Ltd near Dorchester in Blighty are ??
Thinking of fitting a 12v prop shaft generator if the gearbox bearing is a tough one, so I also need to know if the gearbox output bearing is a tough one, or easy to change. Finally any opinions about how good Marine Enterprises Ltd near Dorchester in Blighty are ??
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TNLI
Active member
Sounds like you might be getting mixed up with the injection pump seals leaking ??
penfold
Well-known member
They're big and heavy and some spares are rather expensive, but they're well-built and looked after will last as well as any rivals. I wouldn't seek out a boat because it had a Bukh but I certainly wouldn't discount one either. No idea about the gearbox, but that's not a bukh component so if there was a congenital weakness it would be the maker's(probably PRM or ZF) problem not Bukh's.
LittleSister
Well-known member
Note the DV36 has been available with different gearboxes over the years. You would be more likely to receive informed feedback if you can say what make and model the gearbox you are considering is. (They will also be used on non-Bukh engines.)
My DV36's gearbox is different from the current standard Bukh offering - mine being a ZF brand, model BW-7, which uses the same oil as the engine, not ATF (automatic transmission fluid) which is used in some gearboxes (but it doesn't mean they are hydraulic gearboxes!).
Presumably you are referring to the comments by Jerrytug in post #4 (which relates to the way the seawater pumps are mounted on the DV10 and DV20, not the different arrangement on the DV36), and by Ashley in post #9. The latter does relate to the DV36, which originally had the seawater pump somewhat hidden above the oil cooler on the stbd. side of the engine. I note that the current version of the DV36 has a very different arrangement pictured on the Bukh.dk website, with a belt driven seawater pump mounted on the front of the engine. That should avoid most likely problems, if the engine you are considering has that arrangement, but periodic check and replacement of the impeller is still important, as it is on any engine.
penfold
Well-known member
He mentions keel-cooling so he won't have an impellor to change(obviously the circulating pump has an impellor, but it's not a service part).
LittleSister
Well-known member
That's correct for keel cooling, but that is so rare on leisure boats* I suspect it's just the engine is described so by the seller as 'keel cooling' as that's what it was originally set up for (i.e. an ex-lifeboat engine, presumably). Unless he's actually got keel cooling on his boat, he'll also need a heat exchanger and a sea water circuit, including a sea-water pump.
*(Except for canal narrow boats, perhaps?)
TNLI
Active member
Many former lifeboat engines have keel cooling only, and I want the boat I am building to be both ice worthy and capable of running the main engine whilst beached, or hauled out. One conversion I will be making is to fit a small car radiator and fan with a Y valve, so I can select between cabin heat or keel cooling. I'm also going to look at how I might fit the cooling plate inside the aluminium hull, rather than outside.
A good keel cooling system is far superior to a heat exchanger and sea water pump system. More reliable and no real service requirements.
I managed to meet 2 local fishermen today that both said the company I was looking at are very good. So the only real question now is about the hand start option, and which exact models are available.
LittleSister
Well-known member
On my 1979 DV36 the hand-start 'option' just involves buying a crank handle (and perhaps a gym membership!). Bukh spares being what they are, the crank handle was about £100 last time I looked, but it's simple enough that someone with engineering skills and equipment could make their own.) On my engine the handle can go in either at the forward end of the engine (top side port), or the aft end, roughly above the gearbox, to suit your installation. A shaft runs between the two ends, and if I recall correctly is connected to the engine by a chain.
I'm not sure that hand-start shaft is now standard, and it, or some substitute, may now be an optional extra.
TNLI
Active member
I'm going to buy a reconditioned Bukh from an old decomisioned lifeboat, not a new one. Alas the actual engine model varies from country to country, and with which type of lifeboat and year. Some of them are fitted with some type of spring assisted start, rather than a handle. Plan to visit the engineering shop fairly soon, so hope to be able to find out which model is which in terms of the type of starter units.
Just to confuse things further, I'm having second thoughts about the size of engine required. My lifeboat is 27ft LOA, BUT nearly 2ft of that for the rudder. So in long range fuel economy terms a 36 hp diesel is something of an overkill. The other negative is the weight, as the 36 RME has a net weight of 265 kgs !! That's around 65 kgs more than a Vetus M4.45 which is rated at 42hp.
Weight is very important in both performance and self righting C of G related calculations, So I'm starting to look at some of the other Bukh engines, like the 2 cylinder turbo. Also the same company can supply reconditioned diesels like the Vetus M 3.29, which is rated at 27 hp, and only weighs 134 kg dry including gearbox.
I suspect the free fall lifeboats were fitted with a lighter engine, so a 2 cylinder turbo might be the way to go, as Vetus engines are all painted yellow, and I prefer red!
Tranona
Well-known member
Marine Enterprises also have Yanmar ex lifeboat engines which are also sometimes keel cooled. There are also keel cooled versions of Yanmar, Beta and Mitsubishi used in canal boats. While building in a double bottom, either sealed or open with a cooling coil is common in steel boats, not sure about how that would work with aluminium, although aluminium is commonly used in high performance car radiators.
TNLI
Active member
General slightly off topic reply:
Yes, they recondition most types of small to medium sized dielsel engines. My last yacht, a Van Der Stadt 34 design, with the basic hull and topsides welded together by a yard in Holland, had a 3 cylinder Vetus based on a Mitsubishi block. That engine might have been rather more vocal, and a bit more thirsty than a Yanmar, BUT it was the real McCoy in terms of how it could tolerate serious abuse, as are many types of old rattlers, (Non close tolerance blocks). It never failed in 5 years and nearly 50K miles offshore, including a full circumnavigation. Like the Hydrovane self steering I fitted, it was in the same perfect condition the day I sold Dicha, as when I purchased her. I don't like Yanmars because I had 3 serious failures in 2 years with a 2GM that was fitted to my first yacht, a Pacific Seacraft Dana 24. Injection pump siezed, blown out injector tip and finally, a leaking head gasket.
One word of warning about fitting old Vetus or some other older diesel engines, is that you must read the instructions about fuel feed supply pressure. Fitting some daft fuel filter, like a CAV 296, or similar car or truck part, can result in a lot of problems with lack of power or wondering RPM. The solution often involves fitting a real full flow filter unit, like a Racor 500 FG, (Or correct Vetus filter and supply pump units) with the correct filter rating. If the fuel filter has a glass bowl it must not be located in the main engine bay to pass a commercial inspection, due to potential fire spread risk. It also makes sense to fit emergency bypass Y valves to allow the element to be changed whilst the engine is running.
Aluminium is incredible in terms of how good a thermal conductor it is, so I plan to fit an internal heat transfer system, which might be based on a set of aluminium pipes and plates. Not keen on fitting an outside cooler plate because I'm planning to cover the entire hull below the waterline with very high grade genuine epoxy with about half a dozen layers of fine glass cloth, not the junk polyester or commercial floor epoxy that most boat builders use.
I've done enough research now to know that the engine I need is going to be a Bukh with an emergency start handle and dual keel or inside cabin radiator systems.
As a final backup aux power system, the forward survivors cabin plan includes a small air cooled diesel generator that can supply a pair of 12v electric outboard trolling motors. Should be good for canals, or even slow speed live bait trolling for Marlin, Tuna or Mako sharks, (2 kts with a small Bonito, or large Mackerel).
BIG QUESTION IS WHICH BUKH, as the 36 RME is rather heavy and a tad over the top in long range efficiency terms. So looking at a 24hp model or two at present. Fitting too big an engine can be bad news in long term block life, as older non close tollerance diesels do not like running at near idle power, (Below about 1200 RPM in most cases), as that results in fouled up cylinders in the long term. That issue can be reduced by using max continous RPM for around 30 mins for every 10 hours of idle or low power use.
Any forum member bought an engine from Marine Enterprises Ltd in Blighty ??
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