Volvo Penta AD31

[steve157]

Hi everyone, have just joined up so go easy on me.
Have a problem with my engines, they have trouble getting to full revs under load, they will spin up to 4000revs plus but as soon as they are put in gear they struggle to get past 2000 revs and are blowing black smoke, it does seem the longer they run the better they get but are really struggling to get the boat up on the plane.
Have had them serviced but the engineers were crap, he did seem to think they had new turbos on.
Any ideas would be greatly appreciated.

 

[Viscount]

I have 2 x AD31 and will perhaps be able to help you. Can you fill in your profile so that we know what boat you have? Also useful to understand your outdrive type, final drive ratio and prop type and size. Whilst the black smoke sounds a bit of a problem, it could be that your boat is not set up correctly and that the engines are under unreasonable load.

 

[Channel Ribs]

[ QUOTE ]
...Whilst the black smoke sounds a bit of a problem, it could be that your boat is not set up correctly and that the engines are under unreasonable load.

[/ QUOTE ]

Indeed, the smoke and low revs seem like a symptom of a root problem.

Poor air flow would do it, as would a partially siezed bearing.

I had an AD31 glued to a jet drive and the intake only had to become slightly obstructed and the black smoke / low power thing would happen.

 

[studgies]

Here are some things to check on the AD31's

Make sure the air cleaner is clean

Take off the intercooler and check the tubes are clear and not oill, if oily could suggest the turbo seals are leaking, when you take it off where the tube from the turbo goes into the intercooler make sure there is a large 'O' ring fitted and it is in good condition as any leakage causes the sort of problem you are having.

There are other less easy things to check depentant on your abilities, such as tappet adjustment, injection timing, injector overhaul (must be done at a diesel specialist) blocked exhaust, are the props the correct pitch etc? is the hull clean?

Unfortunately there are lots of factors to cause symptoms like this.

I hope this helps.

 

[steve157]

Thanks for the replys, This is the first diesel boat Ive had so I have a very limited knowledge of diesel engines(ok on petrol's).
The boat is a Carver 28 command bridge, dont know the pitch of the props only that they are duo's.
The air filters were all changed and the bottom is clean as the boat was only antifouled two weeks ago. One engine seems to run better than the other.
Thanks again for any help

 

[Viscount]

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