Smoky Bukh DV10

bumblefish

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Back in the water and finally out for first potter around marina. Engine starts well enough, runs smoothly but when I give her some welly I get dark smoke and a bit of oil from the exhaust. Piston ring?
 
G

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Piston rings allow blow past and you will get high pressures in the sump.

If it is black as opposed to blue smoke then the engine is either getting too much fuel for its revs or too little air.

Is the shaft seized? rope on prop?
Is the air inlet blocked? Some have gauzes that need washing every blue moon?
Is the crank case breather shooting oil into the air inlet? Disconnect it?

Or is it that you have serviced the control linkage and you can now open the throttle past where it used to go?

Is the oil you see actually very fine black powder on the surface of the water. Get a sample? It might just be the un-burnt fuel.

Exactly how much "welly". A boat at rest will take more power to turn the prop than when at top speed. Does it get better when the boat is at speed?
 

bumblefish

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Thanks, I have a feeling it is an air inlet problem. Just re-checked the manual. My air filter is a bit compromised by the companion way steps and may need a re-configuration? However the control linkage has also been adjusted so I will have another look. Thanks again for the pointers.
 

oldharry

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Black / dark smoke is basically caused by incorrect air/fuel ratio. Commonest cause: Overloaded engine - oversize or fouled prop preventing engine revving out fully.

Other common causes: Injector fault giving too much fuel, restricted air intake, incorrect injection timing, incorrect injector pump settings.
 

curious

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If the suggestions you already have do not sove your problem, get on to those most helpful chaps at Bukh, Poole
 

RichardTaylor

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Our Volvo had got smokey over the past 2 seasons, but this season we found the engine unbearably smokey. The injectors were removed and taken to our local diesel service centre (Panda in Fareham) for service.

Having installed the injectors our engine is nearly smoke free and considerably more powerful. £40 well spent
 

curious

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A Bukh 20SME is fitted in our boat and the lads at Bukh Poole correctly diagnosed a problem with the injector pump so off to Panda at Fareham it went who serviced it, fitted new parts and she has gone like a good 'un since.
 
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