Re: Onan ballbearing check and valves values

Gary Silver

Hi All:  
I inquired of Cummins (Onan) about the specifics of changing the generator bearing.  The original person that helped me sent me copies of the updated (latest and greatest) parts and master service manuals for my 7MDKAL-431 genset (posted them in the files section with May 2020 in the title).  He escalated my request for help to his superiors and they responded but indicated that the service should only be done my a "certified Onan" technician.  After explaining to them that several of us (out of a group of owners having about 800 of their gen-sets) had attempted using a "Onan certified technician"  and the technicians had never done it and didn't want to do it.  I finally prevailed on Onan to give me the procedure after explaining that I am an FAA certified aircraft mechanic and know my way around wrenches.  Here is the reply to my questions that I request be directed to a technician who had actually done the procedure: 
Question 1.  Is the rotor able to be self supported when the end-bell is removed.   Answer:  "The rotor can support itself for a small amount of time. I would not leave it unsupported for more than 60 minutes, but it should be fine to remove the end bell"   This is in line with what Craig said relative to a Northern Lights genset.  
Question 2.  What is the degree of engineered interference fit for the bearing in the counter-bore and on the rotor shaft.  In other words how much difficulty can I expect in removing the end-bell.  The service manual says to “tap” it off.  Is that realistic or can I expect a major struggle. Answer:  "I personally used a 2 jaw puller or if the end bell has threaded holes a steering wheel puller to remove it. The other option is to use 2 pry bars at the outside edges and slowly work it off. It is a fairly tight fit or should be unless the bearing began to turn in the end bell housing  Note: be sure to disconnect F1 and F2 as the exciter stator will come off with the end bell."

Thanks to Onan for stepping up and getting me the info.   Now all I have to do is perform this service.  Hope this is helpful to others. 

Gary S. Silver, M.D. 
sv Liahona
Amel SM 2000 # 335
Boat: Puerto Del Rey Marina, Puerto Rico
Me: Farmington, Utah, USA


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