Oil in exhaust when underway

[Nickm9921]

My GK 24 has a Volvo MD5a and when underway at high revs the exhaust blows out an oil slick and black smoke. Note this only happens when underway and not when alongside even at full revs. Does anyone care to enlighten me?
thanks

 

[earlybird]

[QUOTE="Nickm9921, post: 7752880, member: 1876
Note this only happens when underway and not when alongside even at full revs.
[/QUOTE]

Black smoke and a slick point to overfuelling. A number of possibilities, fouled prop, blocked exhaust elbow , possibly a fuel system issue.
Are you in gear or in neutral when alongside? You would not expect this effect in neutral.

 

[Refueler]

My Perkins when full revs has similar and that is because it is definitely getting too much diesel when loaded (in gear)

Black Smoke is the diesel that is burnt (too much). Slick is from the unburnt diesel.

You may be able to reduce it a touch by having injectors cleaned / calibrated - but doubt it will make much difference.

 

[Paulg25]

Blocked air filter?

 

[Refueler]

Blocked air filter?

Could be ... all to do with air to fuel ratio of course ... and how much fuel energy needed for the load at the time ...

 

[Nickm9921]

[QUOTE="Nickm9921, post: 7752880, member: 1876
Note this only happens when underway and not when alongside even at full revs.

Black smoke and a slick point to overfuelling. A number of possibilities, fouled prop, blocked exhaust elbow , possibly a fuel system issue.
Are you in gear or in neutral when alongside? You would not expect this effect in neutral.
[/QUOTE]
It doesn’t happen even when in gear alongside

 

[Refueler]

Black smoke and a slick point to overfuelling. A number of possibilities, fouled prop, blocked exhaust elbow , possibly a fuel system issue.
Are you in gear or in neutral when alongside? You would not expect this effect in neutral.

It doesn’t happen even when in gear alongside
[/QUOTE]

mmmmm interesting ..

 

[anoccasionalyachtsman]

Black smoke and a slick point to overfuelling. A number of possibilities, fouled prop, blocked exhaust elbow , possibly a fuel system issue.
Are you in gear or in neutral when alongside? You would not expect this effect in neutral.

It doesn’t happen even when in gear alongside
[/QUOTE]
How clean is the hull?

 

[Boater Sam]

If a diesel engine cannot reach the revs that the fuel pump expects due to overloading it will produce black smoke and unburnt fuel in the exhaust. If you back off a bit does the smoke clear?

 

[ean_p]

Black smoke and a slick point to overfuelling. A number of possibilities, fouled prop, blocked exhaust elbow , possibly a fuel system issue.
Are you in gear or in neutral when alongside? You would not expect this effect in neutral.

It doesn’t happen even when in gear alongside
[/QUOTE]
have a read here.......https://www.capitalremanexchange.com/causes-of-diesel-engine-smoke-by-color/

 

[black mercury]

Make sure your cold start lever and plunger on the engine are returning after the engine has started. Even though the pull knob is pushed fully home it's possible the plunger can stick on the engine.