BUKH DV20 advice sought

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SimonJ

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I have been operating my Sadler 34 with a Bukh DV20 for 30 years and thought I had a fair knowledge of problems and repairs. I did a major rebuild of the original engine (liners, bearings, valves etc etc) in 2003 followed by lots of motoring to/from east coast of USA, Intracoastal, Canadian lakes etc. Following that in 2010 after returning to UK (motoring much of the way from Antigua!) I replaced it with an ex canal boat (“overhauled”) version. This engine has always been a difficult starter (better once a pre heater was fitted) but has been smoke free and seemingly a good runner apart from a rear crankshaft seal leak.
Now the problem.
It was put to use 10 days ago having been laid up ashore since last September when unfortunately various covid related issues prevented a fresh water/anti freeze flush once ashore. Fuel tank was left full and filters were clear. Before launch a couple of 15 minute runs ashore identified nothing more than the need to overhaul the dripping water pumpseal (a non standard bearing type pump and there had been no water ingress to the lub oil system. After launch two hours motoring to my mooring and then a few days later a brief 6 hour cruise up the coast in no wind conditions went well. On returning engine was started to enter the river to my mooring and while running at low speed in gear after 10 minutes it cut out. Prop fouling was suspected. Restarting proved difficult even though engine had warmed up. When tried in gear it was ok astern but made a rubbing sound going ahead. Was able to proceed slowly to my mooring but there was a background mild growling sound when in gear. Prop was checked next day and not fouled. Tried engine again and had same noises ahead. Then a few minutes later in neutral it cut out After an earlier one off tingling sound. Could not then restart. After about a couple of revolutions the starter could not turn engine. Rocking back and forth by hand cleared the resistance but only for the same thing to happen again.
A few years back at this point I would be calling the wonderful Al and Norman - whose guidance is sadly missed - can anyone else advise?
What further checks can I do? Is that the end of the engine? Could it be the gearbox, water pump/start drive seizing up? Since the inability to rotate issue occurs even when engine decompressed I do not think I have water in the cylinder(s). Can a gearbox issue affect the engine rotation while in neutral? Could a totally failed injector cause the problem. Lub oil level and colour normal.
My first thought for a quick solution was to cut my losses (all parts are very expensive!) and pop in another “overhauled” DV20 or a DV24. Unfortunately none seem available although widely advertised by one well regarded company.
Any advice, ideas would be very much appreciated. And if you happen to know or have a replacement DV20 or 24 ......!
 
I suspect it could be the drive train and first of all with the engine in neutral check if you can turn the prop shaft. This may or not indicate a problem on some gearboxes. However I would then remove the gear box and check the drive plate on the engine and see if the gearbox input shaft can be turned. If the problem still shows up with no gearbox connected I would start thinking Counterbalance shaft and drive inside the engine and hope the engine was rebuilt correctly? Hopefully any damage incurred can be sorted.

I accept that you might have problems doing the above if a Saildrive.
 
First I don't know what your problem is...

But I did have a Bukh 20 until last year and have done an overhaul to a similar depth as you did so I have some familiarity with the engine.

Regarding the reluctance to turn over, will it turn over by hand when decompressed?

The tinkly sound, could that be something to do with the cylinder head valve mechanism? Have you lifted the rocker cover to check?

On the gearbox, are the linkages to the morse control working properly? Have you checked its oil level, they make a noise when they lose it as I discovered when it threw its oil seal out when the prop caught something which stopped the engine dead.

As already suggested, can you turn the prop shaft when out of gear?
 
SimonJ said:
I have been operating my Sadler 34 with a Bukh DV20 for 30 years and thought I had a fair knowledge of problems and repairs. I did a major rebuild of the original engine (liners, bearings, valves etc etc) in 2003 followed by lots of motoring to/from east coast of USA, Intracoastal, Canadian lakes etc. Following that in 2010 after returning to UK (motoring much of the way from Antigua!) I replaced it with an ex canal boat (“overhauled”) version. This engine has always been a difficult starter (better once a pre heater was fitted) but has been smoke free and seemingly a good runner apart from a rear crankshaft seal leak.
Now the problem.
It was put to use 10 days ago having been laid up ashore since last September when unfortunately various covid related issues prevented a fresh water/anti freeze flush once ashore. Fuel tank was left full and filters were clear. Before launch a couple of 15 minute runs ashore identified nothing more than the need to overhaul the dripping water pumpseal (a non standard bearing type pump and there had been no water ingress to the lub oil system. After launch two hours motoring to my mooring and then a few days later a brief 6 hour cruise up the coast in no wind conditions went well. On returning engine was started to enter the river to my mooring and while running at low speed in gear after 10 minutes it cut out. Prop fouling was suspected. Restarting proved difficult even though engine had warmed up. When tried in gear it was ok astern but made a rubbing sound going ahead. Was able to proceed slowly to my mooring but there was a background mild growling sound when in gear. Prop was checked next day and not fouled. Tried engine again and had same noises ahead. Then a few minutes later in neutral it cut out After an earlier one off tingling sound. Could not then restart. After about a couple of revolutions the starter could not turn engine. Rocking back and forth by hand cleared the resistance but only for the same thing to happen again.
A few years back at this point I would be calling the wonderful Al and Norman - whose guidance is sadly missed - can anyone else advise?
What further checks can I do? Is that the end of the engine? Could it be the gearbox, water pump/start drive seizing up? Since the inability to rotate issue occurs even when engine decompressed I do not think I have water in the cylinder(s). Can a gearbox issue affect the engine rotation while in neutral? Could a totally failed injector cause the problem. Lub oil level and colour normal.
My first thought for a quick solution was to cut my losses (all parts are very expensive!) and pop in another “overhauled” DV20 or a DV24. Unfortunately none seem available although widely advertised by one well regarded company.
Any advice, ideas would be very much appreciated. And if you happen to know or have a replacement DV20 or 24 ......!
Click to expand...
Sounds a little like a gearbox bearing, when a ball cage breaks the balls can group together and make the shaft difficult to turn , this can be cleared by rotating back and fore but before long total seizure. The tinkle can be caused by the balls rotating without a cage. But separating the gearbox would be my first step.
 
From my limited knowledge -

SimonJ said:
What further checks can I do?
Has the starter disengaged?

Is that the end of the engine?
Unlikely, but possible.

Could it be the gearbox, water pump/start drive seizing up?
Either are possibilities.

Since the inability to rotate issue occurs even when engine decompressed I do not think I have water in the cylinder(s). Can a gearbox issue affect the engine rotation while in neutral?
Yes. E.g. if (input) drive shaft seized, won't matter if it's connected to the (output) driven shaft.

Could a totally failed injector cause the problem.
I can't see it myself.
Click to expand...
 
Thanks James for commenting. Am starting to build list of checks!
Gearbox linkages/position seem ok - but will check more closely. Engine did stop dead, albeit from very slow - so seal ejection an interesting check.
Can turn shaft out of gear.
Nothing untoward seen with valve gear (had a broken valve spring once in the previous engine so know to look closely!).
Engine similarly becomes tight to turn even when decompressed. Definite feeling/sound of rubbing somewhere but hard to pin down the source.
Have not yet checked gearbox tor lubricant/debris/colour. Will do that on next visit (boat is a dinghy row away on mooring).
 
If it is the gearbox, maybe Marine Enterprises may have a spare one?

They offer a trade in your old engine, when selling you their ex lifeboat engines and I'd be surprised if they didn't have a suitable gearbox lying around their yard for you.

That said, I think they'd be surprised to be asked, they seem to think the Bukh 20 gearboxes are very robust.
 
Whatever it is, it sounds fairly major. If you don’t have access to the gearbox then removal of the engine and box is going to be needed I suspect.
As has been asked already, is the oil level OK? (
 
europe172 said:
Sounds a little like a gearbox bearing, when a ball cage breaks the balls can group together and make the shaft difficult to turn , this can be cleared by rotating back and fore but before long total seizure. The tinkle can be caused by the balls rotating without a cage. But separating the gearbox would be my first step.
Click to expand...
Thanks. More good thinking. That would fit the scenario I have tried to describe. It s the original gearbox and I have motored much more than most. Up and down the ICW twice, Bay of Biscay on three calm occasions plus a lot more. So perhaps even this usually robust gearbox has reached end of life. (And a while back it was the victim of a sudden engine stop with a mid Atlantic cargo net entanglement which sheared two engine mounts.)

I am very grateful for all the many sensible suggestions so quickly given. I will report back after further checks but it may take a while.
 
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