Volvo Penta MD2010 black smoke no power

[jbm1967]

Hi All, I hope someone can help. I have twin MD2010 engines. They have been working fine and then suddenly one of them has developed a problem. It was fine at start of journey and was reving nicely at about 2500rpm. Then I noticed black smoke. The reeves had dropped to about 2200rpm and would not go higher (Normally 3000+). If I pulled throttle back the black smoke stops so works fine at about 2200rpm. Get in the marina and the faulty engine was very very slow to pick up under load even to get to the 2200 max. In neutral it revs fine and picks up quickly but still lots of black smoke over 2500rpm. So I had 2 thoughts. 1) Blocked exhaust elbow but can’t believe this would just happen so suddenly? 2) Fouled prop but why the black smoke when in neutral? So I’m stating to think it may be something else. Changed filters and fuel but still the same. The filter was a little a gunky so could it be a blocked injector? Any help much appreciated sorry for long thread.

 

[maggietwo]

had this problem some years ago on a nani 3 thought it was dirty fuel but someone suggested injectors it turned out to be fuel pump timing

 

[Stork_III]

Sounds like exhaust elbow to me. I had similar, MD2020, came on very quickly, elbow reduced to pencil sized pipe.

 

[jbm1967]

had this problem some years ago on a nani 3 thought it was dirty fuel but someone suggested injectors it turned out to be fuel pump timing

Thanks. Sounds like I may have to take in to a workshop.

 

[jbm1967]

Sounds like exhaust elbow to me. I had similar, MD2020, came on very quickly, elbow reduced to pencil sized pipe.

Thanks. I think I’ll have a look at exhaust elbow before I take to a workshop

 

[peteK]

Blocked exhaust elbow common problem with this series of engines.

 

[jbm1967]

Think (Hope) this is the problem. Now to clean it reassemble and pray!

 

[RichardS]

That looks like the problem. You should check the other elbow as that will probably be heading the same way.

Richard

 

[jbm1967]

Bingo! She’s working fine now. I’ve cleaned as best possible the hole is a lot bigger than before. I’m on my travels so will do properly when I return. I am amazed how quickly this come on. Within the space of 2 hours she goes from running fine to some serious problems.

 

[duncan99210]

Be careful when cleaning the elbows out if you’re away from a source of spare parts. It’s very easy to knock a hole through the casting when you’re trying to shift the built up crud. I got away with it once (down in the back end of the Peloponnese), next time the screwdriver went straight through the wall of the elbow = 10 day wait for a new bit to arrive from Athens...

 

[jbm1967]

Be careful when cleaning the elbows out if you’re away from a source of spare parts. It’s very easy to knock a hole through the casting when you’re trying to shift the built up crud. I got away with it once (down in the back end of the Peloponnese), next time the screwdriver went straight through the wall of the elbow = 10 day wait for a new bit to arrive from Athens...

I was fearful of something like that so I went pretty gentle. Hole is nowhere near the size it should be but she’s running fine and I don’t want to push my luck.

 

[PetiteFleur]

I also had this problem on my previous boat, elbow blocked but my screwdriver went through the casting so had to get a replacement - the Perkins version was slightly cheaper!

 

[Neeves]

Though it looks as if it is blocked with carbon - that is just a 'pigment'. The actual blockage is calcium, carbonate or hydroxide - not sure which. It dissolves in acid - and you can clean the elbow (once only) with acid - much less hassle that bashing with a screwdriver. You can only do it once as the acid, at the concretion needed to completely clean quickly (overnight) also dissolve iron (or Fe). Possibly if you use the acid at a low concentration the Fe will not dissolve - but it wouldltake longer to clean - I'm impatient.

The elbow blocks slowly - but the final few mm of blockage takes the engine from apparently working perfectly to a liability. Its worth taking elbows off every couple of hundred hours to check. I think ours blocks at about 1,000 hours.

The idea that having two engines offers safety and redundancy is a myth. If something goes wrong with one engine the same fault usually develops within hours on the other engine (assuming you keep the hours similar).

Jonathan

 

[grafozz]

Though it looks as if it is blocked with carbon - that is just a 'pigment'. The actual blockage is calcium, carbonate or hydroxide - not sure which. It dissolves in acid - and you can clean the elbow (once only) with acid - much less hassle that bashing with a screwdriver. You can only do it once as the acid, at the concretion needed to completely clean quickly (overnight) also dissolve iron (or Fe). Possibly if you use the acid at a low concentration the Fe will not dissolve - but it wouldltake longer to clean - I'm impatient.

The elbow blocks slowly - but the final few mm of blockage takes the engine from apparently working perfectly to a liability. Its worth taking elbows off every couple of hundred hours to check. I think ours blocks at about 1,000 hours.

The idea that having two engines offers safety and redundancy is a myth. If something goes wrong with one engine the same fault usually develops within hours on the other engine (assuming you keep the hours similar).

Jonathan

I have replaced both elbows with new stainless ones much better and the same cost , now .
I take them off and clean them often easy job and it gives advance warning of blocked elbow .
and I agree moving a boat , cat ? with one engine is tricky !