Albin 28 / Cummins Engine - poor exhaust design

[thomaslong]

For whatever it's worth, I am having exactly the same experience in my 1996 Albin 28. Right now, the turbo is off being refurbished, and a new SS exhaust elbow is being fabricated. Unfortunately, my mechanic was called down to St. Thomas VI for major engine work on some ferries out of Red Hook, so we are all waiting for the new parts and the mechanic to arrive, hopefully at the same time.

My symptoms arose abruptly last summer when my boat would not get up to cruising RPMs, staying about 200 low and therefore 2-4 knots below proper cruising speed. We tinkered around the edges all summer long, checking out the fuel system, rebuilding the Racor and trying to eliminate all the simple (and cheaper to fix) causes. Finally in the fall, I found a mechanic who had worked for Cummins for 26 years; he took readings and determined the problem really was the turbo just not generating enough boost. Ironically, once the weather turned colder here (well, as cold as it gets in New Orleans) the boost went right back up in the denser air, and the engine ran at normal RPMs.

My wife and I spent the winter in Europe so we were not able to get back to our boat until early spring. When my mechanic finally removed the exhaust elbow and the turbo, we found the tell tale signs of corrosion that had eaten a small hole underneath the elbow and eroded the back end of the turbo. It is now clear to me that this problem had been a long time building. When I bought the boat in late 2013, the survey showed that the turbo had been replaced just a couple of years earlier, because it was reported "sticking." Now we know that it had probably suffered the same corrosion as my current turbo. No one had ever examined the underside of the exhaust elbow.

When my mechanic returns from St. Thomas and starts to put my exhaust system back together again, I will ask him about ways to increase the rise. He seems to think that the configuration is adequate, even though history indicates otherwise. We'll keep everyone posted.

[Robb]

Boat goes to the welder next week to fit up the dry side and now I'm looking for a glass guy to do the wet side muffler mod and hatch raising. I'm behind about 2 months due to having to work out of the country.

Just FYI, my engine made it 2600 hours. It was ingesting water through the turbo. Cylinder bore and valves on #5 & #6 were in bad shape.

Had water in turbo within first week of new engine in the water. Pulled the boat, consulted with Tony Athens at Seaboard Marine and redesigned the exhaust system per his design. I do not want to damage the new engine, too much $$$.

I will post more as it comes together.

[chesapeake albin]

PITOU, I sent you a message.
Thank you


Can anyone explain to me how to take the turbo apart and see if it is getting water in there? What am I looking for?

Thanks
TRavis

[Pitou]

PITOU, I sent you a message.
Thank you


Can anyone explain to me how to take the turbo apart and see if it is getting water in there? What am I looking for?

Thanks
TRavis

Message read and replied to.

First step: Remove the dry riser from the turbo and wet elbow and have a peak inside at the fan blades for corrosion. You'll need new gaskets when you replace.

This will be your view:

1.jpg

[RobS]

Kevin, dry riser? on the 28? I don't see that in the pics in the original post of what should be the same setup?

For the 4 turbo flange bolts use a good quality 6pt 10mm wrench, presoak the bolts with pb blaster type penetrant, and when you go to remove the bolts tap the wrench with a hammer to break free. Be sure you have the wrench fully seated and tap it square. Once you round one off or break one is when the real fun starts.

The housing of the turbo could have some condensation surface rust but deep rust scaling is signs of a seawater diet. Important to look closely at the fin tip to housing clearances, if that area is corroding and the clearances are widened you are losing boost. If that's the case likely the seawater is making it's way into the exhaust manifold.

Seaboard Marine sells a nice extra thick graphite gasket for the turbo flange. It's especially good if you have some imperfections in the mounting surface.

[Pitou]

Kevin, dry riser? on the 28? I don't see that in the pics in the original post of what should be the same setup?

My bad Rob .. "Wet elbow" bolted directly to the turbo! How I fluffed that, I don't know as I had the 370 6BTA under the hood of my 28 for nine seasons of ownership!

[RobS]

You've clearly "moved on"

[chesapeake albin]

Thanks again That is very helpful before I start taking things apart.

Why is their not a "flapper" on the outside of the exaust?
Is this a solution to keep the water out?
Is this something that could be done?

Thanks

[RobS]

A flapper on a side exhaust outlet? Flappers are effective for a rush of water when the engine is shut down, like when anchored, especially if anchored off the stern. As far as solutions it's all about maximizing the spillover height, which is what this thread is all about..

[Robb]

Got the welded dry section completed and just had the heat shield made. Fitted up on the boat. All fits great. Just need to modify the muffler this weekend and put back in the water. Just FYI, the turbo only had 40 hours on a full reman. Look at the corrosion in that short time. Should not happen again, have about 20" of vertical clearance now. I'll confirm an exact number once the boat is back in the water as I still have the tubing connected to the seacock.

[Robb]

Finally made some time to get the engine cover sectioned and raised 7 1/2". Tried to get a fiberglass guy to do, but no one could touch it until winter. Glad I worked my way through college at a boat yard, the rusty fiberglassing skills came back.

Fairing will have to wait until later in the fall. Time now for a quick trip to the ocean and San Juan's before the kids head back to school.

[Pitou]

Robb - Looking good and nice follow-up throughout your project. You did a great job at helping out the forum by spelling out the ABC's of spillover for those that need a better understanding of how to take care of and improve upon the production boat builder philosophy of "good enough" and their "get it out the door" faults.

You've had a long road. Enjoy your well designed worry free exhaust!

[RobS]

Yeah, looks good, exactly what I was envisioning on that engine box raising.
Enjoy the trip and the pc of mind that comes with the new safe setup. Save travels.

Also, that expansion tank looks "interesting", I'd keep a close eye on those elevated mounts...

[Robb]

Rob,. I know what you mean on the elevated mounts, but Tony at Seaboard has done this way. They are way heavier than they look and with the cross bracing it is a very rigid structure. He was very insistent that the tank be at least 1/4" higher than his turbo to fitting. I am a little worried about long term fatigue cracking, but every design is a compromise. I will just work this inspection into my daily prestart check. Main design goal of minimum 12" (20.5" actual measured in water) spillover height was meet with flying colors.

Now on to more enjoyable winter projects like repainting the cockpit sole and installing a swim platform. It will be nice to work on projects I can see and enjoy rather than engine mods.

Thanks to everyone in this group for there thoughts and comments. This will close out my posting on this topic.

[RobS]

Cross bracing is important, I didn't see that in the pics. Sounds good, yeah I agree if there is gonna be anything going on with the brackets it will be some minor fatigue cracks starting that you would pick up on your routine checks. Kudos for tackling this one! Everything else should feel easy peezy..