Volvo Penta D6-350 White Smoke + Knock Sound

[Lax207]

Good day sailors!

Need your thoughts on something here. Our Starboard engine now, seems to blow out some white smoke following some knocking sounds just upon acceleration around +- 2000rpm. Main fuel filters and Racor has been changed. We run a 30 micron and 10 micron setup before fuel comes to the main fuel filters. There was quite some dirt on the filters before but before the test, filters have been changed and ran for a 3 hour cruise with good results on the filter ( not black in colour or sediments present).
We have also done an injector test, please see picture attached and videos. Can it be the injectors? Anyone experienced anything similar?

Video: https://www.youtube.com/watch?v=99N4xdoHQ0s


Thoughts appreciated!
Chris

 

[omega2]

overfueling on one??

 

[Lax207]

So injectors then? 1 & 3 seemed kindda much

 

[kashurst]

that knocking noise could be quite a few things
is it outdrive or an IPS boat?
have you/can you listen to the engines with the engine cover/hatch open. It could be transmission/drive noise or something knocking as the boat accelerates.
Not enough info to condemn the injectors just yet.
What kind of test did you do to the injectors?

 

[volvopaul]

This relates to a previous post when the engine required a major stripdown , I remember some parts falling into the sump .
Did you remove the engine for a full stripdown , if not then I’d say your definitely looking at one this time .
The D6 is a good engine , white smoke is poor combustion so I’d be looking at a compression issue for a start , if the injector was infecting neat fuel then the rail pressure would drop dramatically causing it to shut down .

 

[Lax207]

Hi kashurst, the engine uses a DPH sterndrive. This sound occasionally is also heard when gear is in idle and you rev the engine rather quick. A slight knock and then it dissapears. The white smoke is only during acceleration. During cruising speed around 2800rpm it is clean of white smoke.

 

[Lax207]

This relates to a previous post when the engine required a major stripdown , I remember some parts falling into the sump .
Did you remove the engine for a full stripdown , if not then I’d say your definitely looking at one this time .
The D6 is a good engine , white smoke is poor combustion so I’d be looking at a compression issue for a start , if the injector was infecting neat fuel then the rail pressure would drop dramatically causing it to shut down .

Hi volvopaul,
Yes previously was the port engine when it underperformed and spit out black smoke. It was 2 exhaust valves that created the problem and a broken rocher bearing on the rocker arm which fell on the sump. We got a few out but some still remains down on the sump. Knock on wood so far engine performs great. This time is the starboard with the white smoke only upon acceleration. Have you had similar experience with this? We are thinking to first check/replace injectors. Have bad some dirty fuel before so we are thinking this can be the cause. Maybe clogged injectors?

 

[Lax207]

Hi kashurst, the engine uses a DPH sterndrive. This sound occasionally is also heard when gear is in idle and you rev the engine rather quick. A slight knock and then it dissapears. The white smoke is only during acceleration. During cruising speed around 2800rpm it is clean of white smoke.

Oh and the injector test we did was justbthe return flow test as you can see on the picture.

 

[Lax207]

Update Video!

https://www.youtube.com/watch?v=1NoOctmj6Vs

You can hear at 00:20 the knock sound form Port engine. At this point it emits black/white smoke just as it tries to get off plane. Injector return flow test results picture attached. Seems like our first step is to replace injector 5 & 6.