Black smoke

[Allan]

I have twin Volvo 71Bs (380hp) they run extremely well up to 2200 rpm and then smoke very badly. the bathing platform is covered in black soot, max. rpm should be 2600 with a clean bottom but have never gone beyond 2500. Anybody got any ideas to help, Engines are well serviced, I believe, and the oil and filters changed. Problem seems to arrise only when under load.

 

[markc]

Black smoke is unburnt fuel. I would guess that if from both engines the boat maybe overpropped. If from just one it would either be an air problem - turbo requiring servicing, heatexchanger full of crud (prob only if bearings on the way out on turbo) or the injector pump needs recalibrating.

All IMHO as I'm no mechanc!

M

http://www.geocities.com/jinto100/Jintopics.html

 

[BarryH]

If they've idled or run at low revs for most of their life it could be that the bores have glazed up

Wha'dya mean "I'm always playing with this engine" its the only way to get it to run!

 

[longjohnsilver]

Could be either of those. Do the engines reach full revs when not under load, if so then almost certainly over pitched props are the problem.

To check the engines are getting sufficient fresh air you could lift one of the floor panels when under load to allow more air in, again if this cures it then you'll know that you need better ventilation.

 

[david_steward]

Re: Check out....

www.boatdiesel.com

Look at the servicing section and all of your questions will be answered.




Please insert your smart ass pretentious tag line here...


Dave S

 

[DepSol]

Funy you should mention that as Soltron have been doing some testing recently on this subject and has been found to reduce glazing dramatically. Not saying that Soltron is an aid in this case as there are so many other factors to take into account like filters fuel quality and all the other possibilities that are being posted.

Just thought I would drop that in for info purposes.

Dom


I just want my boat back in the water ;-(

 

[ToMo]

In about a hundred years time someone will look at your headstone and will read 'DepSol - he was always trying!'...........yeh you got it - very trying! <G>
TôMö

 

[DepSol]

The way things go with this forum it wont take a hundred years maybe a hundred posts!

Dom


I just want my boat back in the water ;-(

 

[dickh]

Also check that your water injection elbow on the exhaust is not choked with salt & soot - mine only had a small contorted hole thro' the centre - approx ¼" diameter!! Like a new engine after I'd replaced it.(and after I'd had the injectors and fuel pump overhauled...)
dickh

 

[Guest]

Tell me what boat arethey in?, is the bottom clean, might be overloaded 2500 rpm is not bad for an old engine and heavy boat, suggest test injectors for a start, fit new air filters, do boost test at inlet manifold, check for play in turbo shafts, if one engine is down the other will not perform either, test each engine separately by running one in gear then the other, they should pull the same revs if not then the lowest is not right, start on that one.
On an engine of that year, this is from recent work done to a 71b, the intercoolers get clogged with oil from the turbos, slowing down the air intake through them, answer is to remove the intercoolers, clean with a degreasing agent and build back with all new seals and gaskets etc, also as in the recent case, the lower housing corrodes away, this was the stb engine where you could not see the bottom area, this allow pressureised air from the turbo to escape not boosting the engine, hence no power and clean burn etc. PM me if you need anymore, where is it lying I might be able to take a look.

Paul js.

 

[Guest]

Having suffered from both soot on the transom and not hitting full revs at full throttle (I have a Phantom 40 with Cats) I got a Cat engineer to check whether the engines were running at full power- which they were You may want to try this although sadly you'll have to go to a proper Volvo engineer and with Marine labour rates £40 ph and up it won't be cheap. At least you will know that it isn't all the various mechanical things people are suggesting.
After this it can only be that the engines are being asked to work too hard- boat now heavier, trim angle too great, props damaged.
A am currently having my props checked by Clements- if they find that they are still to the original spec I only have trim angle and weight left- in my case I suspect a combination of both. I will be having the props de- pitched if there is no damage, as I am told that you significanatly shorten the life of disel engines if you "lug" them- doesn't matter at what revs if this is happening.

Hope this helps
Bob

 

[Guest]

Bob most problems on an engine of that age are component related, just had another case this week of melted exhausts near the silencers, its all a process of separate elimination, a vp engineer cannot wave a magic wond, after reading other post, half of the dealers are not far short of useless anyway, employing untrained non marine engineers, often subcontracting work out as well and charging vp rates. I am a freelance engineer working on all makes of engines but mostly vp, IMHO they are one of the best alrounders to have, albeit very costly on parts but not many special tools are req to do major work on them, unlike the cats that you have, you cannot even test the injectors , other than by a cat dealer, now that is not really on, who wants to be in the clutches of them? I wonder.
paul js.

 

[Allan]

THANKS FOR YOUR HELP. THE FOLLOWING ARE THE ANSWERS TO YOUR QUESTIONS.
1) THE ENGINES ARE IN A 1992 SEALINE 450
2) THE BOAT IS LYING IN BRIXHAM DEVON
3) THE STARBOARD TURBO HASE BEEN REPLACED AND THE PORT HAVE BEEN SERVICED RECENTLY
4) BOTH ENGINES HAVE THE AMERICAN FUELSEP TURBO AIR FILTERS FITTED
5) MAGNETS ON BOTH FUEL OUTLETS ALSO FITTED
6) VP HAVE CHECKED THE ENGINES (?????)

THANK YOU IN ADVANCE FOR ANY COMMENT

ALLAN

 

[Guest]

Try rpm match next time at sea, airsep filters, what are they made of, should have 2 paper filters in each housing, do the engines breathe smoke from the breather filters when under load, airsep I understand puts crankcase fumes back into the engine via the air filters housing, Volvos are not really designed for this, suggest if this has been done then intercooler matrixes, it has 2 per engine are slightly blocked, do you have boost gauges?, have you had an impeller failure recently?, suggest melted exhaust, possible, have you tried this since new scrub off etc, what top speed do you get? is it trimmed right tabs etc, how long have you owned the boat, are you used to it etc, explain the magnet system, is it supposed to be a fuel conditioner to stop smoke, I am not really into gimmicks like these .
paul js

 

[Allan]

HI AGAIN;

hAVE OWNED THE BOAT FOR TWO YEARS. I BELIEVE THE BOAT WAS TRIMMED CORRECTLY BUT WILL CHECK AGAIN WHEN I DO THE TESTS YOU SUGGEST.
I AM NOT INTO GADGETS EITHER, THEY WERE THERE WHEN I THE BOAT AND YES THEY ARE SUPPOSED TO CLEAN FUEL. THE FUELSEP FILTERS ARE AS YOU DESCRIBE AND HAVE NOT BEEN CLEANED FOR 12 MONTHS. THE MANUFACTURERS CLAIM THAT ONLY THEIR CLEANIG FLUID SHOULD BE USED AN THE FITLER SHOULD BE OILED. I BELIEVE THEY HAVE THEIR OWN WEB SITE.
ILL GET BACK TO YOU WHEN I HAVE MORE INFO.

 

[Allan]

HI PAUL REPLY NO. 2
FUELSEP FILTERS MADE BY WALKER ENGINEERING NORTH HILLS CAL. USA
FOR INFO TRY WWW.MARLINMAG.COM

REGARDS ALLAN

 

[Guest]

Sorry for delay- first time I've been back!! (Business pressures...) I had the Cats tested for power- they were both pulling the 350bhp that 3116's should develop- just not at 2800 rpm. Surely that answers your componant point?

I know I 've got to go to Finnings for all detailed work on the engines- as you say no options there

Bob