My old Volvo MD11C - and soot

[AiniA]

My MD11C starts well and seems to have good power ... but generates quite a bit of soot that collects on the wide, flat transom of my Nonsuch 30. What I have done so far is take off the exhaust manifold and exhaust elbow and acid clean them. The injectors have been serviced and the tech said they were fine.

From my research other things to try (in order from easiest to hardest to do):

• Clean the air intakes
• Remove and clean the rubber exhaust hose (about 6' long
• Remove the fuel from tank and clean tank and fuel

Any thoughts?

[bil56]

if it smokes, it’s working!
propeller and hull are clean ?
si le moteur tourne haut, quelle couleur la fumée ?

[AiniA]

Originally Posted by bil56

if it smokes, it’s working!
propeller and hull are clean ?
si le moteur tourne haut, quelle couleur la fumée ?

I happens after being on the hard with new bottom paint. There is relatively little smoke but seems. black, but not oily on a paper towel

[Wotname]

Is this a new issue or has it been doing it 'forever'?

If it is a long term problem, your prop maybe is the wrong size.

Can you achieve max rpm at wide open throttle with clean bottom and prop in calm water? IIRC, max rpm for the MD11C is 2,500.

[Lepke]

Soot is part of having a diesel. But too much fuel or too little air creates soot. If you have an air filter, take it out and see if it helps the soot problem. Most big marine diesels don't use an air filter, just a screen.