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White smoke in reconditioned Bukh engine

tmtracey

Member
Joined
29 Nov 2009
Messages
52
I am getting a fair amount of white smoke from the exhaust of my reconditioned Bukh DV24 engine. Please can someone give me a set of practical steps to identify the issue!

I installed the engine 2 years ago. It generally sounds very good, and starts first time, although sometimes slightly sluggish to get going.

It didn't smoke initially but has got worse, and really increases with more throttle.

I haven't used the boat very much in the last couple of years. The diesel in the fuel tank is probably a year old.

I am on a swinging mooring and bring her out in December. Is it best to address this now or once back on dry land (when it’s colder and likely to exacerbate the white smoke)? A series of starter steps to help narrow things down would be very helpful.

Many thanks for any help. Toby
 

jamie N

Well-known member
Joined
20 Dec 2012
Messages
3,524
Location
Fortrose
Common Causes of White Smoke:
• Damaged Injectors
• Faulty Injection Timing
• Damaged Crankshaft Keyway
• Damaged Timing Gear
• Low Cylinder Compression
• Damaged Rings or Cylinder Liners
• Water mixed in the Diesel Fuel (Cracked Head Gaskets, Cylinder Head or Block)
• Damaged Fuel Lines
• Low Fuel Pressure to the Fuel Pump
• Damaged or Incorrect Fuel Pump Timing.
This was copied from this site. Good luck.
 

tmtracey

Member
Joined
29 Nov 2009
Messages
52
Yes it definitely is smoke, has that strong smell.

Some more information:

There was some liquid on the top of the engine - having cleaned this up and checked it while running, I believe this is oil leaking from the cylinder head cover gaasket.

I don't think the injectors are leaking.

I was wondering if it's worth trying some cheap and easy solutions first before taking the thing apart - eg. Wynns Stop Smoke Oil Treatment. Which might show valve blow-by.
 

cherod

Well-known member
Joined
2 Dec 2018
Messages
4,847
compression test ,,,,,,, i always thot white smoke was a water issue , head gasket .
 

Biggles Wader

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Joined
3 Mar 2013
Messages
9,306
Location
London
Im thinking simple checks first
More throttle,more smoke suggests overfuelling which might be caused by dirty air filter or exhaust constriction.
Also fouling of prop or dirty bottom-engine labours and smokes.
 

Boater Sam

Active member
Joined
14 Mar 2020
Messages
574
Location
Philippines and Thailand
Increasing white smoke with revs would point me towards retarder injection timing. Can you mark the pump's present position and advance it by a few degrees to find out? To advance. it needs to move in the opposite direction to normal rotation.
 

neil_s

Well-known member
Joined
28 Oct 2002
Messages
1,204
Location
Chichester
My Bukh DV20 is the same! Was accosted by passing boat and told my engine was 'cooking'. Temp gauge said 60 C. With a following wind, the exhaust smelled of diesel smoke - no unburnt fuel component at all. It was running at full throttle at the time, though, on it's last outing before lay up. I don't think I will worry too much about it!
 

tmtracey

Member
Joined
29 Nov 2009
Messages
52
I know that Bukhs do have a tendency to smoke a little but mine is quite a chugger!

Boater Sam- you may be onto something there. At idle, it hardly smokes at all, but it increases with revs, and is pretty much full blown at full throttle. So maybe a timing issue..

It also runs quite cool so I don't know if that suggests anythin - I ran it for half an hour on Monday, and the head cover was completely cool to the touch and the engine block only slightly warm - though temp gauge was normal 60C.
 

vyv_cox

Well-known member
Joined
16 May 2001
Messages
23,340
Location
France, sailing Aegean Sea.
Bukhs are renowned for steaming, probably due to the cooling passage design. Two areas to check are the water injection point into the crankcase, behind the flywheel, and the elbow. Carbonate deposits at either location can increase steaming. The steam will often smell of diesel.

When I have had white smoke due to injector problems it was unmistakeable, huge clouds of stinking smoke that hung around for 15 minutes.
 

Boater Sam

Active member
Joined
14 Mar 2020
Messages
574
Location
Philippines and Thailand
Bukhs are renowned for steaming, probably due to the cooling passage design. Two areas to check are the water injection point into the crankcase, behind the flywheel, and the elbow. Carbonate deposits at either location can increase steaming. The steam will often smell of diesel.

When I have had white smoke due to injector problems it was unmistakeable, huge clouds of stinking smoke that hung around for 15 minutes.
Good call, you need to establish if its steam or fuel. A rag over the exhaust should give the game away, if its steam it will just be wet, if its unburnt fuel it will get oily and show rainbows in the water when you wash it out.
 

LittleSister

Well-known member
Joined
12 Nov 2007
Messages
13,438
Location
Me Norwich - Boat Orwell & Southwold
Are you sure it is smoke, and not steam?
Bukhs are renowned for steaming, probably due to the cooling passage design. Two areas to check are the water injection point into the crankcase, behind the flywheel, and the elbow. Carbonate deposits at either location can increase steaming. The steam will often smell of diesel.

When I have had white smoke due to injector problems it was unmistakeable, huge clouds of stinking smoke that hung around for 15 minutes.
Good call, you need to establish if its steam or fuel. A rag over the exhaust should give the game away, if its steam it will just be wet, if its unburnt fuel it will get oily and show rainbows in the water when you wash it out.
Thanks both. I will have another check and report back.
I've been Lakesailored! In fact double-Lakesailored! :oops: :D
 

wiggy

Well-known member
Joined
13 Jun 2001
Messages
1,439
Location
Portsmouth Harbour
My reconditioned engine (new pistons needed) smoked after being reinstalled. The guy who did the work gave me some running in oil to put in it for a few weeks, apparently it’s helps new rings seal properly) after a few weeks the smoking had stopped and I replaced the oil with standard diesel oil. All sorted.
 

Moodysailor

Well-known member
Joined
7 Sep 2020
Messages
606
As mentioned by a few, white smoke is either from water, or incomplete combustion. In the latter, it is usually a fuel system issues (fault with injectors or fuel injection pump), but I the relatively low temps might indicate that the engine is running too cool and this is causing the problem. You may have something as simple as the incorrect thermostat fitted during rebuild that is preventing the engine getting up to temperature.

Either way, you have a couple of options the way I see it: use the advice on here and other places and work through a process of elimination (start with the lowest cost), or get a good engineer to take a look. They won't be able to check for this type of issue out of the water, so if using an engineer do it before you come out or when you go back in.
 

tmtracey

Member
Joined
29 Nov 2009
Messages
52
Well, I learnt a few things about the engine yesterday chugging up and down the Deben!

It was a fairly warm day (16-17C) and the smoke wasn’t as bad as I’ve experienced before. On a cold day, it can be much worse.

On start-up, there was big smoke for about 10 seconds and then it disappeared. I let it idle on the mooring for 30 mins (about 900 RPM), and then set off, gradually building the revs over about 2 hours. There was no smoke whatsoever until it reached 1700 rpm when a faint small cloud starting coming from the exhaust. At 1900 rpm it had thickened but was not extending much from the boat. From 2000-2100 rpm, it started to smoke heavily from the exhaust. It was greyish white (mainly white), and extended about 5 feet back from the boat, before dissipating.

I’ve put a video here of it running at 2100 rpm
Engine smoke

2100 rpm is the highest available with my throttle set-up. The company that reconditioned it suggested a cruising speed of 2000-2400 rpm, so I would like to be able to achieve that smoke-free..

Some noticeable things were-
  • It took over an hour to get to 60C water temperature and only gradually reach that – is that normal? After 30 mins idling, it was only at 50C. Once it got to 60C, it stayed on that the entire trip. I could only hold my hand on the engine block itself for about 5 seconds,, which seems normal.
  • The amount of smoke dramatically increases from 2000 rpm - so once it reaches a threshold, it really smokes.
  • However when on the mooring and in neutral, I put the engine up to 2100 rpm. There was NO smoking whatsoever. So something about being under load is creating smoke.
I am fairly sure it was smoke, not steam. As it only smoked on the move, it was tricky to check but I tried holding a rag on a stick in the fumes close to the exhaust – it didn’t get particularly damp (to indicate steam), or absorb any fumes to create a rainbow effect in water, as someone recommended checking. Anyway it certainly looked like smoke to me.

Apart from the slow initial increase in the water temp, the other gauges read normal the whole session. The air filter and exhaust look new and clean. I cleaned the cooling water ‘poker’ last year and flush it every winter. The volume of water coming from the exhaust was good (about 12 L/min when idling after the trip).

Hopefully this helps with understanding the issue - any further advice/comments much appreciated.
 

Beneteau381

Well-known member
Joined
19 Nov 2019
Messages
1,107
Well, I learnt a few things about the engine yesterday chugging up and down the Deben!

It was a fairly warm day (16-17C) and the smoke wasn’t as bad as I’ve experienced before. On a cold day, it can be much worse.

On start-up, there was big smoke for about 10 seconds and then it disappeared. I let it idle on the mooring for 30 mins (about 900 RPM), and then set off, gradually building the revs over about 2 hours. There was no smoke whatsoever until it reached 1700 rpm when a faint small cloud starting coming from the exhaust. At 1900 rpm it had thickened but was not extending much from the boat. From 2000-2100 rpm, it started to smoke heavily from the exhaust. It was greyish white (mainly white), and extended about 5 feet back from the boat, before dissipating.

I’ve put a video here of it running at 2100 rpm
Engine smoke

2100 rpm is the highest available with my throttle set-up. The company that reconditioned it suggested a cruising speed of 2000-2400 rpm, so I would like to be able to achieve that smoke-free..

Some noticeable things were-
  • It took over an hour to get to 60C water temperature and only gradually reach that – is that normal? After 30 mins idling, it was only at 50C. Once it got to 60C, it stayed on that the entire trip. I could only hold my hand on the engine block itself for about 5 seconds,, which seems normal.
  • The amount of smoke dramatically increases from 2000 rpm - so once it reaches a threshold, it really smokes.
  • However when on the mooring and in neutral, I put the engine up to 2100 rpm. There was NO smoking whatsoever. So something about being under load is creating smoke.
I am fairly sure it was smoke, not steam. As it only smoked on the move, it was tricky to check but I tried holding a rag on a stick in the fumes close to the exhaust – it didn’t get particularly damp (to indicate steam), or absorb any fumes to create a rainbow effect in water, as someone recommended checking. Anyway it certainly looked like smoke to me.

Apart from the slow initial increase in the water temp, the other gauges read normal the whole session. The air filter and exhaust look new and clean. I cleaned the cooling water ‘poker’ last year and flush it every winter. The volume of water coming from the exhaust was good (about 12 L/min when idling after the trip).

Hopefully this helps with understanding the issue - any further advice/comments much appreciated.
its steam, much as vyv cox said, doesnt look excessive to me.
 

vyv_cox

Well-known member
Joined
16 May 2001
Messages
23,340
Location
France, sailing Aegean Sea.
Definitely steam. The water passages and supply on Bukh are quite small, e.g. the standard seacock is only 1/2 inch, unlike every other engine. Add in a little deposit in the two places I mention, plus in the manifold adjacent to the head, and boiling water at the elbow is the result.
 
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