Yanmar 27 HP smoking when around 3000 rpm

[Samaral]

Have a friend in Brazil that asked this to me. He noticed that when he revs up his engine to 3000 rpm it starts to smoke. Taking back to 2700, 2600 everything looks fine. He said he has a engine maintenance scheduled to October. Does this problem sounds really bad or you guys think he can wait until October to have the engine serviced? I have no clue about Diesel engines and I don't know what to say to him.

 

[JohnShannon]

what color? Each color means something different white is one thing (water I think) black is another (overfueling?) etc.

 

[centerline]

just guessing but maybe try and clean the air intake filter..... could be dumping more fuel in to go faster but the air system could be restricted so as not having enough air to burn properly.... or it could be an injector problem....

 

[seadaddler]

Lower Rpm's

Should not be a problem until he has it serviced,he should not run the RPM's at 3000 that often and 2400-2600 is a good cruising speed.
Nick

 

[Gunni]

Has he changed his prop? Smoking exhaust can be a sign that the engine is being bogged down by an incorrect prop pitch. And it is an immediate concern because the engine may be loading with carbon and the mixing elbow may clog. Overheating to follow.

 

[Benny17441]

Would venture to say he has a fouled bottom or prop. The engine is likely overfueling at 3000 RPM emitting a dark black smoke. The best service is to dive the boat and scrape and clean any marine growth from the hull and prop.

 

[Samaral]

Thank you all for the replies. I think, but not sure, he didn't replace the prop and also I think the hull it is fairly clean. I would go with air filters and maintenance related problems, once he mentioned he is overdue with the schedule maintenance.. Anyways, I will pass to him all these suggestions..and also suggest his to subscribe to the forum. )
Thanks again!!!!

 

[Ross]

Diesel engine try to ru at the demanded speed. If the load exceeds the hp the engine will emit black smoke.

 

[Samaral]

Just a quick feedback: the problem was growth at the propeller. After a nice clean up the engine is working like a charm!!!! I can not believe the difference that makes. Thanks again for all the replies.
Sergio.