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    Onan Generator Failure-gctid397956

    Hello all

    My 8.0 KW onan in my 1989 38 has a serious failure.

    While running it began making a loud squealing sound. It started to smoke from somewhere - seemed to be the generator section. The electrical output remained fine. I shut down and felt the end housing of the generator and it was very hot. Believe the bearing in the generator has failed.

    Has anyone experienced similar and what was the good and bad of the repair.

    I have the parts manual and it shows a single bearing on the end of the generator - the side to the engine seems to be bolted/fitted directly to the engine thus no bearing there.

    Any input would be appreciated.

    Ron
    Ron O'Blenis
    B 38 175 Hinos 1989
    Completed Great Loop
    https://ronandfaye.blogspot.com/

    #2
    Check the alternator and belt

    Ron

    Comment


      #3
      I had a similar happening....but it was the front end of the generator...the circulation pump froze up. Replaced it and all is well.

      Comment


        #4
        Check with Cummins factory rep in your area. Sounds like a bearing. They should also be able to direct you to a factory authorized repair tech in your area. I have had trouble with mine - gaser -MME 8KW -- (no bearing failures yet) and find that everyone says they know how to fix these Onans but few actually have any real skill sets. I had a so called local expert look at mine but I had to provide all the manuals...he had none. How good can you be without a service manual? Any way... best of luck on this. Keep us updated as to what you find.

        Comment


          #5
          For all that maybe interested.

          I have found the problem - as suspected, a failed rear bearing in the generator.

          The bearing was completely void of grease. The bearing carriage failed.

          I have found recomendations that the bearing should be changed every 500 hours or 5 years because the lubrication dries out and is lost. The bearing is a sealed unit so there is no way to lubricate.

          Would say that anyone with a Onan 8.0 kw in a 38 or similar aged boat should expect that the bearing will fail.

          I have replaced it - but no small job.

          As a help to others, removing the end bell be very careful in removing nuts that hold the end bell. Mine were actually rusted on and they are on a stud that runs through the gen casing to the engine. Mine actually broke free at the bell housing and I backed out the whole stud. I also broke one but used a stud remover to finally get it out.

          The end bell will drive off with some hammering - used a piece of rebar to get to the right spots. The end bell carries the bearing. It is held by an O-ring so it will come off relatively easy once the end bell starts to move. Be sure to unplug the field wires that are on a terminal block mounted on the end bell.

          Pulling the bearing was ok once I found and adapted a puller to fit the bearing. The new bearing drives on fairly easily with a block of wood and a large socket to finally seat it.

          Have fun - I would recommend that others change the bearing sooner than later. Mine failed in a manner that did not cause the shaft to rotate off center which would take out the stator - don't want to think of that.

          Boating can be so much fun.
          Ron O'Blenis
          B 38 175 Hinos 1989
          Completed Great Loop
          https://ronandfaye.blogspot.com/

          Comment


            #6
            RDOIII wrote:
            For all that maybe interested.

            I have found the problem - as suspected, a failed rear bearing in the generator.

            The bearing was completely void of grease. The bearing carriage failed.

            I have found recomendations that the bearing should be changed every 500 hours or 5 years because the lubrication dries out and is lost. The bearing is a sealed unit so there is no way to lubricate.

            Would say that anyone with a Onan 8.0 kw in a 38 or similar aged boat should expect that the bearing will fail.

            I have replaced it - but no small job.

            As a help to others, removing the end bell be very careful in removing nuts that hold the end bell. Mine were actually rusted on and they are on a stud that runs through the gen casing to the engine. Mine actually broke free at the bell housing and I backed out the whole stud. I also broke one but used a stud remover to finally get it out.

            The end bell will drive off with some hammering - used a piece of rebar to get to the right spots. The end bell carries the bearing. It is held by an O-ring so it will come off relatively easy once the end bell starts to move. Be sure to unplug the field wires that are on a terminal block mounted on the end bell.

            Pulling the bearing was ok once I found and adapted a puller to fit the bearing. The new bearing drives on fairly easily with a block of wood and a large socket to finally seat it.

            Have fun - I would recommend that others change the bearing sooner than later. Mine failed in a manner that did not cause the shaft to rotate off center which would take out the stator - don't want to think of that.

            Boating can be so much fun.
            Good job!

            The bearings fail from mostly lack of use. We often see the bearings last for decades if the generator is used regularly. Of course sometimes they fail early.

            You got lucky in that it didn't take out your generator end.

            We were not so lucky. I looked over the generator pretty carefully when we surveyed our boat, but there is no way to check or grease the end bearing. When I ran the generator to really try it out after purchasing the boat the end bearing failed, taking out the generator end.

            The moral of the story is to use your generator.

            Why do industrial backup generators last so long???

            They get exercised every week automatically.

            KEVIN SANDERS
            4788 LISAS WAY - SEWARD ALASKA
            www.transferswitch4less.com

            Whats the weather like on our boat
            https://www.weatherlink.com/embeddab...59665f4e4/wide


            Where are we right now? https://maps.findmespot.com/s/36S4

            Comment


              #7
              Ken

              Thanks for the compliment.

              I was glad that I am able to fix things myself - I estimate that this was $2000 repair for a "factory tech" when adding travel, back to the shop for parts, etc. The bearing - even from Cummins - was only $31. I also don't think a service tech would have worked as hard to get out the broken stud - that could had added twice as much effort as the whole generator end would have to come off.

              Sorry you where not so lucky - but I think your experience adds to my thought that these bearings are a maintenance item.

              I will certainly plan to change again in five years - and with antiseize on the bolts it should come apart much easier.

              Also have enjoyed your posts on the rebuild and trip home - safe and happy boating.

              Ron
              Ron O'Blenis
              B 38 175 Hinos 1989
              Completed Great Loop
              https://ronandfaye.blogspot.com/

              Comment


                #8
                RDOIII wrote:
                Ken

                Thanks for the compliment.

                I was glad that I am able to fix things myself - I estimate that this was $2000 repair for a "factory tech" when adding travel, back to the shop for parts, etc. The bearing - even from Cummins - was only $31. I also don't think a service tech would have worked as hard to get out the broken stud - that could had added twice as much effort as the whole generator end would have to come off.

                Sorry you where not so lucky - but I think your experience adds to my thought that these bearings are a maintenance item.

                I will certainly plan to change again in five years - and with antiseize on the bolts it should come apart much easier.

                Also have enjoyed your posts on the rebuild and trip home - safe and happy boating.

                Ron
                Hey Ron

                I have to be honest, if I would have not been heading out on my delivery trip, I would have just fixed the generator. I'm a Marathon Dealer and would have just put a new Magnamax generator end on it and been done. But I am glad to have ther new Northern Lights unit all the same.

                Its a challenge when your boat is 2000 miles away, and you have a limited amount of time on the ground to fix things. Now that its near me, I'm doing 100% of my own work. Thats part of the joy of boating.

                I'm glad you found a new bearing. I didn't know Cummins was still supporting the old YD generator ends. I used to fix and sell the voltage regulators from those units on Ebay untill the demand dried up several years ago. That generator end, and as a matter of fact the DJ engine was one of the best engines ever made. In their day they would beat a Northern Lights hands down. They were that good, although a bit noisey.

                KEVIN SANDERS
                4788 LISAS WAY - SEWARD ALASKA
                www.transferswitch4less.com

                Whats the weather like on our boat
                https://www.weatherlink.com/embeddab...59665f4e4/wide


                Where are we right now? https://maps.findmespot.com/s/36S4

                Comment


                  #9
                  Kevin (sorry about using my cousins name in the last post)

                  The parts seem very availible - at least from the Cummins factory distribution system. I needed a new stud, small terminal board, and o-ring for the bearing seat - as info I hunted half a day for the o-ring but it seems it is a very specific size and diameter.

                  I am curious about your comment about the regulator and also the generator and engine type. Can you provide a few more details including where parts options to Cummins might be had? The engine is a Kubata D950 and I have had some luck with parts from a Kubata dealer for the engine - but I was not sure where parts for the generator could be found. Incidentally, the regulator is a tranformer type.

                  Thanks again for your posts
                  Ron O'Blenis
                  B 38 175 Hinos 1989
                  Completed Great Loop
                  https://ronandfaye.blogspot.com/

                  Comment


                    #10
                    RDOIII wrote:
                    Kevin (sorry about using my cousins name in the last post)

                    The parts seem very availible - at least from the Cummins factory distribution system. I needed a new stud, small terminal board, and o-ring for the bearing seat - as info I hunted half a day for the o-ring but it seems it is a very specific size and diameter.

                    I am curious about your comment about the regulator and also the generator and engine type. Can you provide a few more details including where parts options to Cummins might be had? The engine is a Kubata D950 and I have had some luck with parts from a Kubata dealer for the engine - but I was not sure where parts for the generator could be found. Incidentally, the regulator is a tranformer type.

                    Thanks again for your posts
                    OK, I was off a little on your model in my head. (Your generator is newer than I was thinking)

                    If you have the Kubota engine, then you probably have a Stamford Newage generator end on that unit. Onan/cummins started outsourcing around that time frame.

                    If you do, you can just use Stamford Newage parts for your generator end. That might save a buck or two... Cummins seems to be pretty high on their prices.

                    KEVIN SANDERS
                    4788 LISAS WAY - SEWARD ALASKA
                    www.transferswitch4less.com

                    Whats the weather like on our boat
                    https://www.weatherlink.com/embeddab...59665f4e4/wide


                    Where are we right now? https://maps.findmespot.com/s/36S4

                    Comment

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