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AD41B exhaust smoke & sooting

J

Jeff Cowley

New member
Hi, My 35 foot Riviera powered by twin AD41Bs is smoking heavily from the port engine & covering the boat in black soot.

I have just aquired the boat & sailed across Bass Straight (approx 23 hours) & noticed the problem worsened during the journey.

The previous owner has replaced the turbo, reconditioned the head & fitted new injectors to the engine.
I am new to these engines & diesels particularly & am seeking advise as to where to start to remedy the problem.
I have removed the air filter & the turbo spins freely & appears to a novice to be clean.
The pipe from the turbo to that aftercooler is also clean.

Refuelled after the first 2 hours running & used 57 litres per hour (both engines) cruising at 12 knots, 3200rpm & flat seas.
Expected to use approx 40 litres per hour. The engine didn't use any oil on the journey & the problem seems to be with the fuel system.

All & any advice would be appreciated.
 
57lph seems a little high for a pair of 200's running at those rpms, but I don't know that those engines are particularly efficient. As a comparison I cruise my 43ft game boat at 18knts and 80lph with twin 330 common rail engines. i.e. more efficient (lpNM) than your 35 Riv with twin 200's. Those older Rivs weren't known to be an overly efficient hull design, but even so your 57lph sounds a bit expensive. As another comparison, our 36ft sport cruiser with twin KAD32 (170hp) cruises at 40 - 45lph and 22knts. I think 40lph may be optimistic for the Riv, and maybe ~50lph more likely.
Relatively simple things to check would be air filter and boost pressure. Even if the turbo is good, could there be a leak in the intake system? Does the engine make full WOT rpm's as easily as the other engine, or does it lag a bit in power? After that you get into injectors, valve clearances, injector pump timings, compressions etc. You could also look at the exhaust elbow for blockages, but if the turbo has just been done you would assume that this was checked already. Does the engine run at the same temp as the other one or a bit hotter?
Final thought is that 12knts on a 35ft boat is probably a very inefficient speed as you are probably 'riding the hump' and neither displacing nor planing efficiently. This could be contributing to your engines over fueling as they are running 'overloaded' unless the boat is propped for this. I would try lifting your cruise rpm's to say 3400 and see how your liters per NM change. It may well be a more efficient speed and easier on your engines if the hull starts to plane more efficiently. I think those engines go 3900 at WOT(?), so max cruise rpms would typically be listed at 3500 - 3600, but check that as I don't know the AD41B very well.
 
Thanks,
Gives me plenty to work on.
Temps on both engines same
Have not tested at WOT but will.
The air cleaners were both new & are now both very sooty.
Suspect we have an exhaust leak at the elbow.
Have the turbo off now.
Initial inspection found it was "sticky" to spin but after disconnecting the exhaust elbow & removing some soot it now spins freely.
I intend to refit & try some of the other checks suggested.
 
If that is a relatively new turbo and it has 'sooted up' to the point of sticking already then you may have an issue with some form of over fueling (overloading, bad injectors, injector timing, restricted air flow etc). Are the boat bottom and running gear all clean, or could they have growth on them?
 
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