Volvo Penta AD41B, 150 HP Diesel

[Ray61]

I recently had problems with my DP-A 290 Sterndrive. The gear oil was black, so I sent it to the place I bought it from for inspection. He said the cone clutch was slipping real bad and all the parts were blue from the heat. I gave him the ok to rebuild it and he recommend changing the lower unit to 1.95:1 gears. Not sure what the ratio was before. I was running A5 dup props and the acceleration and speed were ok. WOT was 3600 RPM.

Since I reinstalled it after rebuild, the acceleration is very slow with lots of black smoke until I get up on plane, then WOT speed is great at 30MPH and no smoke, RPM 3850. The turbo charger and precooler check good. I'm guessing there is too much load on the engine at low speed so I'm thinking about changing to an A3 or A4 props with less pitch, but WOT RPM will probably be too high. Engine placard says 3250 RPM. I would appreciate any suggestions!

 

[alldodge]

Tell me if I missed something

Your motor WOT rpm by spec is 3250
Your old ratio drive WOT rpm was 3600 with A5 props
The new 1.95 ratio WOT rpm is now 3850

If above is correct you need more pitch not less, and the rebuilder did you a disservice

The black smoke is your over fueling
Did you see all the smoke before the drive was rebuilt?

 

[Ray61]

Thanks for the reply. No, I did not have the black smoke before the repair. My mechanic is telling me to replace the turbocharger. Can you suggest a good turbo shop for a repair or exchange?

 

[alldodge]

Can you suggest a good turbo shop for a repair or exchange?

Have not had a turbo repaired but have had injection pump repaired at Diesel Injection Service Inc. They did a great job, but did have a slight issue after install. They drove 160 to my place and fixed it, quick

Have you checked the air filter, all hoses and connections from filter to intake? If the filter is clogged, intake has a restriction or your loosing pressure at the after cooler will cause this. If you can install a pressure gauge on the after cooler to see what kind of pressure your getting

 

[Ray61]

AllDodge, thanks for the help on this. The connections from the air filter to intake are solid. I will hook up a pressure gauge to my after cooler. Can you tell me what the pressure range should be?

 

[alldodge]

Unable to say for sure, but most larger ones run it the 30 to 36 psi (2 to 2.5 Bar). So if you can get close to 25 I would feel better about the turbo and look more for a leak

 

[QBhoy]

sounds strange to change the drive ratio from the standard. Is the mechanic at at ?

Having had a couple of VP DP290 drives, all be them attached to GM petrols, I can tell you that I was once worried by the dreaded cone clutch slipping. On two occasions. One time was early in ownership and the oil grade was too light for the drive and water temp. That solved the problem and discoloured oil problem.
Secind time was water in the oil...as these have a habit of. I solved this by using the merc fibre seals as well as the VP o rings and silicone over the screw each year.
Bottom line is that these things are hardy drives often throw issues like this just through the above reasons. Lots of people get confused as to the right oil for these. Loads of wrong info on these. Some say engine oil, some the wrong weight rating. The simple answer for me was GL5 75w-90 gear oil.

 

[Ray61]

His reasoning for the change was that it was a better match for my boat, and it does run faster. I was using the correct gear oil in it, 75W-90. My turbo charger is only 3 years old, but it did freeze up recently and would not turn. got it unstuck and seems to spin freely with good output pressure now. I have ordered a pressure gauge to measure it. I'm having a hard time locating a free volvo series 41 Technical Data Manual that has the correct turbo charger pressure specs. I would not be surprised to find the pressure too low and have to replace the turbocharger. Thanks again for your help. I will let you know what I find.

 

[Ray61]

Looking for a Volvo Penta series 41 Technical Data Workshop Manual.

I need the turbocharger pressure specs for my AD-41B engine.