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TAMD 41B problem

Sorry, I should have replied long ago!

In the end, the problem was solved. Again, it was a result of poor repair work, done by the (only) Volvo Penta-licensed shop around. When they replaced part of the exhaust system (removing the engine & leg in the process), and put the leg back on, they replaced the exhaust-to-leg bellows, but didn't bother to install a clamp on the leg end. As a result of steering, the leg end of the bellows came off the leg & folded over, almost completely blocking off the exhaust. This caused enormous back pressure and, of course, huge amounts of smoke. In addition, though, it gave a fairly free path for seawater to travel up to the turbo housing, allowing seawater to stay in there all the time (causing corrosion etc. of the turbo itself). In addition to all of that, the portion of the exhaust that did escape, while under way, emptied directly in front of the props, causing massive cavitation (and destroying the props in the process).

In the end, I found another (non-Volvo Penta certified) mechanic who discovered all of the above, and fixed it all. After a full hull cleaning, scraping & painting, the above repairs, and new props, we took it out for a run and got her up to 27.5 kts., which is more than 3 kts. higher than the manufacturer's specified max speed attainable.

So...bad service + repairs = around 5 1/2 months $ $7K to fix, but now (as of last October, anyway) it runs great. Hopefully, sitting in the cold Pacific since then hasn't caused any new issues!
 
Thanks for the reply! And after the exhaust being sorted out can you now get the required rpm´s from the motor. What is your wide open throttle rpm under load.
 
IIRC, I'm getting close to 3700 RPM before I pull it back. I can cruise comfortably at 23-24 kts. at 3400 RPM.

With the new turbo, it fairly jumps out of the water now - I swear, I could pull a skier out of the water! It used to take a looong time (20-30 seconds) to reach 2300 RPM, where the turbo would spool up, and the boat would surge forward. Now it does it in just 2-3 seconds. Engine is quieter & smoother, too. I guess I was lucky - my new-to-me mechanic was able to find & instal a NOS Volvo Penta turbo for around $400!
 
This was an excellent thread. I am hoping I will not have to rebuild my Turbo + after cooler to solve my issue as zetec7 did, but I have very similar symptoms. I'm on a Cape Dory 30 Flybridge with 2x TAMD 41B Volvo Penta. The port engine ran fine three weeks ago, but last weekend ran well up to 2000RPM and could not get it higher than that, with black smoke increasing with throttle. No smoke at 1800RPM. Starboard engine ran fine up to 2800RPM and I did not push the asymmetry farther than that.

I checked the Port air filter and similar to zetec7 had some oil due to proximity to the crankcase breather. Putting those two as neighbors is like a Gary Larson Trouble Brewing sketch. I wonder if there is a way to reduce oil from crankcase getting in to air filter. But it was not terrible and I don't think it was root cause. I will try running without filter.

On the Turbo, a photo of the compression wheel today looks the same as it did 2 seasons ago. I strongly suggest people take photos of these for reference in the future. However, I failed to check rotation of the turbo compressor wheel; that is my next step and hopefully it gets me moving.

Two years ago my Starboard Turbo Compression wheel catastrophically failed. The ends of all the compression fans broke off, some into the air filter some into the after cooler. The boat ran great the day before, and the event remains unexplained, but the starboard turbo was replaced by the yard fixing the issue. Former owner replaced the turbos three years before that (?!?). Neither of us are lead foots, what gives?

In my debug I became aware that the Cape Dory 30 does get the occasional backwash from the ocean up the exhaust side of the turbo, so I'm not sure how to protect it from rust. Maybe it's going from stuck OFF to ON fast enough to damage the blades in some cases [Starboard], and in other cases it's not spinning at all [Port]?

The other observation is Port is much louder than Starboard. So based on zetec7's feedback on rebuilding the after cooler+turbo and noticing quieter engine, I'm hopeful I can identify a gasket that need servicing to both improve air compression and reduce noise. I would be interested if anyone noticed noise improvement from servicing seals on the after cooler or turbo. Thanks again for your debug on this 10 years ago, great starting point.
 
Follow up from today's visit.
- The Port engine turbo compression wheel spins freely.
- The turbo air filter was dirtier with oil than I remembered, so it's possible root cause which would be great.
- Engine oil level is full, maybe even too high (dipstick photo below). Maybe possible that it's over filled and the crankcase oil filter is getting some oil to turbo air filter since such close proximity
- Compressed air exiting the Turbo to the Inlet Pipe connections seem solid. The conection pipe has no play and clamp looks good. Don't see any other possible air leaks, but visibility is poor.
- There is oil under the turbo/crankcase area that I cleaned up. The turbo oil connections could be the reason. Or maybe it's from the crank case air filter. I'll put down new matts before the next sea trial and replace the crank case filter.
 

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I had a similar problem on my 41B and it turned out to be the oil feed to the rocker shaft, 2 O rings. Run the motor with the back valve cover removed and look for excess oil coming up from the rear of the head. What happens is the oil floods the rear valve cover and spills out of the breather. 4 hour job to replace 2 O-rings. Happened on both motors over the last 9 years of ownership.
 
Sure thing. Considering the tight space in your Hellion kit, the 6766 Turbo Filter with the smaller E cover should work well. Just make sure you have enough room for the turbo and filter to avoid any installation issues.
 
Tommy2t said:
# 30 is the O-rings and check # 29 for cracks
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Thanks @Tommy2t. I looked twice on all sides and was not able to find #29. Can you give me a hint where? I opened top covers too (photo attached). I put new pads down and will monitor for any new leaks.

After changing crankcase oil filter and air filter the boat recovered, I can get above 2000RPM and plane out. No black smoke, 16kts at 3400RPM for both engines. Everything looks good.

The crankcase does not easily sit well in the housing. I have a photo attached where the crankcase filter is on crooked and would be difficult to know, but this might be the origin of the oil from before. Thanks everyone for the help!
 

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joorjig said:
Sure thing. Considering the tight space in your Hellion kit, the 6766 Turbo Filter with the smaller E cover should work well. Just make sure you have enough room for the turbo and filter to avoid any installation issues.
Click to expand...
Thanks for the tip @joorig. These look like they will not have any filtering of the air. Is this a long term concern for the engine, or do people have experience using them on the TAMD 41B? Thanks for feedback.
 
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