Cummins Marine Diesel Repower Specialists Forums Cummins Marine Engines Cummins 6BTA5.9M turbo failures

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  • #19990

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    I have a 31 ft. Boston Whaler sportfish with twin 1989 Cummins 6BTA5.9M engines. Engines have about 1750 hours. 250HP, CPL 953. Three years ago I had a turbo seize up which was replaced by a Cummins tech. A year after that one, the other turbo did the same thing. Cummins tech replaced that one as well. Both failures occurred after a winter in storage. The boat is always laid up for winter for about 5 months. Before starting the engines in the spring, I disconnect the fuel solenoid valves and crank the engines over until I get good oil pressure. Then reconnect wire and start engines before the boat is launched. On the way home from the boatyard this spring, all seemed well until I got out to open water and tried to accelerate…..no boost…all I got was a lot of black smoke. idled the boat home, removed the K&N air cleaners….and yup, both turbos are seized up.

    Because of the cost, I’m doing this job myself. I’ve always been good about maintenance. oil changes every year, only use fleetguard oil filters, and Cummins blue oil (Valvoline). The boat is by no means abused….typically 65-75 hours a season (wish it was more). I cannot understand why this would happen. I know quite a few Cummins guys as I work in the transportation industry and deal with Cummins service and engineering depts. regularly. Talking to all the guys I know has only come up with one idea that seems to make some sense. The oil feed lines to the turbo possibly breaking down and partially clogging the oil feed to the turbos. The lines were original, stainless steel braided hoses. Needless to say I’m putting new ones on with this repair.

    Repair is going slow as I work full time but I’m getting there. I did find some issues with the exhaust elbows so I’m having them done as well. No signs of water leakage to the turbo however. Turbos are sooted up a bit but other than that, no visual signs of damage. Compressor side looks fine. Also replacing all injectors as I’ve noticed a bit more smoke than I used to see and also some fuel in the exhaust water while idling at the dock.

    Sorry for the long winded story but has anyone ever heard of this happening? Any ideas on why something like this could/would happen? Lastly and most importantly, any suggestions on how I can prevent it from happening again? Hard questions to answer I understand, but figured someone out there may have had something similar happen. Looking forward to seeing your replies. thanks!

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Viewing 20 replies - 1 through 20 (of 40 total)
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  • #21871

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    Hey Tony

    Have the boat running now and seems to be running well with one exception. seems I have a small coolant leak at one of the head bolts. It’s small and I’m not using much coolant but want to fix that. Big concern obviously is head gasket… but hoping a retorque of the head will take care of it. Just wondering what your procedure is for re-torqueing the head. Do you loosen all head bolts and then torque in recommended sequence or loosen 1 bolt at a time and retorque?

    Not sure if you had a chance to look at the pics I sent but would like to hear your thoughts on freshwater coolant system and turbo failures……

    Thanks

    Glenn

    #21787

    Manuel De Liso
    Participant
    Vessel Name: Namasté
    Engines: Cummins 6BTA 5.9 M1
    Location: Imperia
    Country: Italy

    I will do my holidays now and will redesign all as I come back.
    I will post some pics of the work.
    Thanks for the moment.

    #21781

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Your exhaust design is “beyond scary”………………I suggest you study this and all that is here for the few weeks. If you are really studious, you can do this in about two weeks and come back with what really needs to be done..

    https://www.sbmar.com/category/articles/exhaust-systems/

    Tony

    #21688

    Manuel De Liso
    Participant
    Vessel Name: Namasté
    Engines: Cummins 6BTA 5.9 M1
    Location: Imperia
    Country: Italy

    Hi guys,
    I’m from Italy and I’ve just joined the forum.
    I have recently bought a boat with twin 6BTA 5.9 with underwater exhausts. This layout is scaring me since the first day.
    First of all I think the elbows have not enough gradient and the mixing point is too close to the turbo outlet.
    The second is the diameter of the pipes, I’ve never seen such a big diameter 125mm.!!!
    I post some pictures.
    Are my doubt right?
    What if I change to normal exhausts going out from ther stern?
    Thank you for all your suggestions and sorry for my bad english!

    #21651

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    not sure Rob. to be honest I always close the seacocks when I open them. My guess is the caps are very close to the LWL.

    #21650

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Yeah, tight with the turbos tucked under that rear gutter/stepdown area. When you pop the caps on those Perko strainers do you need to close the seacocks or are the caps just above the LWL ?

    #21647

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    couple more

    title of the photo should give you some info of which engine and

    #21638

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    pictures

    I’ve tried to get shots that will give you a feel for the set up. Its difficult to get better shots as the access is tight.

    #21409

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Glenn,

    Let’s try this………………………………..How about some good pictures of the engine room showing the installation from all angles and perspectives.. We are all at a disadvantage here as without “seeing” your exhaust set-up , it’s really hard to go or comment any farther..

    Plus, I’d like to see you current fresh water plumbing, referencing the email you sent asking about a possible upgrade..

    Tony

    #21376

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    Tony

    Not sure why you keep driving the “in denial” thing. If I was in denial I wouldn’t be reaching out for your or anyone else’s input. I get it….you think it’s a poor exhaust system design and salt water is getting to the turbos. I think in a previous post I agreed with the saltwater exposure idea, but I’m not convinced its due to a poor exhaust system design and I’ll explain why.

    This boat is nearly 30 years old with the original engines. I’ve owned it for just about 20 years. The first turbo failure I had was 3 years ago, the second 2 years ago (on the other engine ) and then both failed when I launched it in the spring. I don’t know if either of the turbos were replaced prior to my owning the boat but I had if for 17 years and didn’t fail a turbo. On this failure, I found the bad elbows. Clearly these elbows were degrading over time….every year they got a little worse. At this point, there was no “mixer” as the inner wall was completely corroded. The “original” turbos lasted at least 17 years and perhaps 27 years if they weren’t changed by the original owner. Then the first set of replacement turbos lasted 2 years on one engine and 3 on the other engine. If the failures were solely due to exhaust system design, I should have been failing turbos every few years. Surely I would have failed a turbo or two during the first 17 years.

    When I look at that failure history, it tells me something changed over time. The design certainly didn’t change… the condition of the elbows did. Originally I was going down the oil feed path because of the failure history…. Not having any failures the first 17 years and then all of a sudden I fail both, and one of those replacements lasts 3 years and the other 2 years. Oil feed lines breaking down on the inside and preventing sufficient oil flow to the rotating section seemed plausible. At that time I didn’t know about the elbows. Now that I have that piece of the puzzle, it makes sense and I agree it was salt water that did the damage. But I’m not convinced it’s a result of the design. Could the system be better??? of course however the space constraints make that difficult.

    Does any of this make sense to you?

    #21255

    Philip
    Participant
    Vessel Name: 2007 35’ Cabo ‘FUGA’
    Engines: Cummins QSC8.3-540’s
    Location: Long Beach, CA

    Without seeing the old parts, and with the limited photos I can only guess we will see this same issue at some point in the future.

    You can always throw parts at a problem but until you take it to the next step and figure out why it happened you will only be buying time.

    Statistics say turbos usually have shortened life due to water ingestion. it could be from exhaust system design which from the limited photos looks like it could be better even though it’s been stated there is no room. Fact is there is room but it’s going to take a commitment to make it right.

    One other way water ingestion path could have occured if the crane operator allowed the bow to go low when pulling the boat for the winter allowing water to run into the turbos.

    #21235

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Glenn,

    You will “see” nothing from the manufacturer .. Why would they admit they have issues…………… Think about that..

    You are not only dreaming, you are basically in denial as to what is going on, although I did not want to go that direction…………..SAD!…….

    I am sorry for this, but, I only tell it like it is. ……….It’s really only this simple in your case, meaning, 1+1=2
    …………….. Without that, I would never still be doing what I do..

    Tony

    #21213

    Bill Fuller
    Participant
    Vessel Name: Audax
    Engines: Yanmar 4LHA-STE
    Location: San Diego, CA
    Country: USA

    Bill

    Just an FYI, He already changed out the turbo. Old, frozen one is gone, unfortunately.

    #21195

    Bill Desmarais
    Moderator
    Vessel Name: Extremist
    Engines: Cummins 6BTA 370
    Location: Portsmouth, NH
    Country: United States

    Glenn,

    Sorry for turbo troubles.

    I now own my 5th 6BTA 370. I too have never heard of a turbo failure on a 6BT/6BTA due to an oil feed issue.

    Turbo failures are most always due to salt water getting in to the exhaust side of the turbo and rusting/freezing all up.

    You’ll have to remove the exhaust side flange (4 bolts) from the turbo and “look in and take pics of” that side of the turbo to rule out salt water intrusion.

    Ya it’s a hassle to remove it for a look/see but it is the only way to rule out the most likely cause.

    Keep us posted,

    Bill D

    #21194

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Will be interesting to see what they have to send you..

    #21184

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    gotcha Rob. I reached out to Boston Whaler today. Hopefully I’ll have something useful from them.

    #21158

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Glenn, my boat is in infamous Moriches Bay…

    #21151

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    Good morning Tony

    I had mentioned earlier in this post that I no longer had the seized turbos….had to return the cores so I can’t show them to you. Also, I’ve attached pictures trying to show the exhaust system layout as best I can. I’m trying to give you the info you need…not sure what else I can do.

    #21145

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Glen,

    Over the 30 + years I have been dealing with issues EXACTLY like you describe, I have had end users, supposedly good independent mechanics, and certified Cummins techs tell me there is no signs of water damage, yet the turbo seize up during NON-USE times………………………….. In 100% of every case like that they all had NO CLUE what was happening..

    You came here for help, correct?

    Then do this—————Let ME SEE inside your exhaust side of the turbo and let me also “SEE” your exhaust system as installed on the boat….All this back and fort with all this verbiage and all this “measuring” will accomplish absolutely nothing until I “SEE” what in going on..

    Your call from here..

    Tony

    #21141

    glenn maerki
    Participant
    Vessel Name: marian J
    Engines: Cummins 6BTA5.9M 1989 CPL 953
    Location: long island new york
    Country: usa

    Rob

    Thanks for your response. It’s difficult to measure with the boat in the water but the turbo centerline is a little higher than the generator exhaust exit and I measure that at about 15-16 inches above the waterline. Some estimating is required for sure. I do have a light fuel load in the boat that I didn’t account for so perhaps the turbo centerline is maybe 13 or 14 inches above the fully loaded WL. The engine exhaust outlets are for the most part above the waterline but with a full fuel load, the bottom of the pipe is in the water… I have a contact at Boston Whaler that I will try and get drawings showing elevations. Maybe I’m wrong but I don’t think I’m too far out of the ballpark. Looking at the diagram of spillover, If I’m right about the height of the turbo centerline, then the 12 inch minimum spillover should be there even though I don’t have a “riser” section built into the elbows. Another piece of info….this is an express config and there is a step up of 12 inches from the cockpit to the helm area of the boat…maybe that gives you a better visual of the setup.

    BTW…where are you on Long Island. I live in Babylon…maybe you’re close enough to take a look??

    Thanks again for hanging in with this Rob. Seems like you’re the only one left… 🙂

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