Piles of black smoke Yanmar 3GM30

[Tim Mills]

My boat has been sitting for about 2 months. I went to run the Yanmar 3GM30 tonight and this is what happened. Starts fine, idles and runs great when not in gear up to 3,000 rpm. In gear, piles of black smoke and won't run more than 2,000 with almost no forward propulsion. Fuel looks good. New filters this season. Had a lot of work done last winter including new SS elbow and exhaust manifold, rebuilt and pop tested injectors and cleaned and tested cooler. Good cooling water flow. It ran great all summer including a 6 day trip with lots of motoring.

Stuck injector? Any thoughts?

 

[heritage]

The first thing I would look at are the injectors. Take all three to a diesel injector shop. For about $100 per injector, they can bring them back to life.

 

[Tally Ho]

Prop fouled? Sounds like the engine runs fine.

 

[NYSail]

Agree..... check your prop

 

[Ken13559]

3rd that...check prop for fouling.

Ken Y

 

[RoyS]

4th that, Prop. Put boat in neutral with engine off. Try turning prop shaft by hand from behind engine. Should turn easily in both directions.

 

[Claude L.-Auger]

5th the prop fouling also. Had it happen to me years ago when in Mississippi. My boat was left without being used for 2+ months. On my first outing after that period, I thought my tranny was ruined as I could not get the RPM above 2000 while in gear. A quick dive for a look-see revealed a prop completely covered with barnacles. Cleaning the prop solved the issue. And while at it. I had the diver clean the hull as well. Boat ran perfect after that. You say the boat ran great all summer so prop fouling is the first thing I would look at before getting into injectors and anything else. Good luck

 

[Tim Mills]

Thanks all. Will do.

 

[Ralph Johnstone]

Has anyone mentioned a fouled prop ?

 

[Tally Ho]

Has anyone mentioned a fouled prop ?

Dang,

Why didn’t I think of that

 

[Bluenose]

Did you ever find out what the problem was. I had the same thing, and it was a badly fouled bottom.

 

[Tim Mills]

Did you ever find out what the problem was. I had the same thing, and it was a badly fouled bottom.

All: you guys are awesome. Just had the hull cleaned this week. All is well with the world! It was the dirty prop.

 

[Ralph Johnstone]

It was the dirty prop.

I know that is something you just can't wrap your head around until the first time it happens to you.

Beginning of the season. As with you, my engine ran perfectly as always in neutral, but in gear, great clouds of black smoke and no push. Almost got kicked out of the marina for excessive pollution on my way over to the boat lift. When it came up, the prop looked like a basketball stuck on the end of the prop shaft. How it got me to the lift, well, they're still workin' on that one.

Even stranger yet is that it only happened that once and never again going on 10-12 years. If I get 1-2 barnacles on the prop, it's a bad year.