Volvo AD41B Black smoke amp poor economy

" I have a twin engine install

" I have a twin engine installation with Volvo Penta AD41B diesels with the 290 legs. One engine has started smoking and gets lower fuel economy than the other engine. I changed all the filters, cleaned the turbo, rebuilt the aftercooler, checked the injectors and had the injector pump overhauled none of which made a bit of difference. Any ideas? Thanks in advance.

Larry in Honolulu "

" Larry,

Has this engine lo

" Larry,

Has this engine lost any performance ? What rpm can you get @ WOT ?

Karl "

I haven't noticed a signi

I haven't noticed a significant loss of power beyond the normal that comes with it being time for my annual haulout to remove marine growth. I used to get 3900 RPM but both tachs (my second set) quit working awhile ago so I don't know the exact RPM anymore. I suspect I've lost a little though.

" Larry,

I suggest you get

" Larry,

I suggest you get a Volvo dealer involved to run a thorough test including boost pressure and fuel pressure. This should be done on both engines for comparasion. Valve clearance should be checked/adjusted. I would avoid tearing into the motor before this is done - without the test data you are flying blind and without direction.

Did this problem occur over time or suddenly ? Searching your memory; Did this start in connection with any other event, modification to the boat or service wiork on the engine(s) ?

Karl "

" Thanks Karl. Factory traine

" Thanks Karl. Factory trained Volvo mechanics that will come to ones boat are nearly impossible to find in Honolulu. But I completely agree that I need these tests. I've been looking for such a trained person, but no luck so far. I've even though of trying to buy the equipment myself.

In answer to your question, it seems to me that the problem occurred gradually. My first thought was to clean both turbos which I did over a year ago and that seemed to help for awhile. But the smoking came back and, this time, cleaning the turbo didn't help. Here's an update: Thinking it might be some kind of exhaust blockage, I removed the exhaust elbow. There wasn't any extreme carbon buildup, but the elbow was so rusted inside that very little, if any, coolant could get through. Do you think hotter exhaust going into the turbo could contribute to my problem? Thanks for all your help!

Larry in Honolulu "

" Larry,

Have you tried a c

" Larry,

Have you tried a company called "Pier 18" ?

I doubt that your exhaust elbow issue has anything to do with your problem but it needs to be addressed anyway so....

Karl "

" Karl,
First I want to thank

" Karl,
First I want to thank you for taking time to support all of us suffering boat owners and would-be diesel mechanics. We rarely get that kind of support over here even when we pay for it. I called Pier 18 today and asked if they would help me check the turbo charge pressure and the fuel supply pressure. They said, "We can't come out and do work on boats because our insurance doesn't cover that." According to the workshop manual, I need to check the charge pressure "under full load and at full acceleration" so I figure the only way is in the water.

Anyway, I replaced the exhaust elbow and re-adjusted the valve clearances. The engine seems to run a little better, but still emits considerable black smoke at around 2500 RPM. Nobody I know (except you) seems to have a clue about to resolve this problem and if there are any other factory trained Volvo mechanices working in this town, I would sure like to know about them. Thanks again

Larry in Honolulu "

" i don't know if it will

" i don't know if it will help, but black smoke usually means a restriction to the air flow, or bad injectors(pissing, instead of spraying)..... "

" Larry,

First thing I woul

" Larry,

First thing I would check is boost pressure. This is not difficult. You need two gauges and you need to make an adapter that connects the gauges to the manifold. There are a couple of large plugs on top of the intake manifold. These can be drilled and taped to accept the gauge. Once you are done you plug the holes (tapping 1/8 NPTF usually is the way to go). You should check boost on both engines at the same time to identify any difference. If lower on the "problem" engine look for air leaks first. Any chance that the prop(s) are different/damaged ? This could cause an overload condition giving you these symptoms.

Karl "

" Thanks Karl. I'm gettin

" Thanks Karl. I'm getting the stuff together to test the boost pressure. I have certainly looked for air leaks, but I'm not sure where they would be -- perhaps the aftercooler, but I can't see anything. It seems like the smoke is worst at intermediate speeds. There is much less smoke above 3000 RPM and below 2000 RPM. As for the props, I changed tham all at the last haulout. They are size A5 and I've inspected them for damage and/or marine growth and they look ok.

On a related note, I've had a lot of trouble with my outdrives having them rebuilt about every 18 months. Someone suggested to me that I may be running too much prop. But when I first bought the boat, I was able to get 3900 RPM out of them, so I thought the A5 size was OK. "

" Still getting tons of black

" Still getting tons of black smoke at intermediate RPM. Turbo pressure is ok, (15 PSI at max acceleration under load). I've checked almost everything. Question: Is it possible to get normal turbo pressure even if I have exhaust restriction in the exhaust manifold? I'd hate to tear the engine apart for nothing. If not, I think I'm back to suspecting the injector pump. I had it worked on once already and thought the guy knew what he was doing. Thanks for any help/advise. "

" Larry: To add to what Karl i

" Larry: To add to what Karl is saying, while you have the plugs out ,take a small mirror and look inside the intake chambers to see if their is any carbon restrictions in theses chambers.Look for air leaks in all connections from the turbo to the head . Takes two people as the Boat must be under load and up to speed. Make sure the after cooler is not opening up at the seam when pressurerized. Del "