TheOldHokie
Well-known Member
- Location
- Myersville, MD 21773
I just received another oil pump to rebuild and I thought I would share some more thoughts and experiences. In a previous thread we discussed problems with some of the aftermarket rebuild kits -specifically the APN6600B kits for pumps with "3/4 inch" gears. The pump I have in hand uses the original 9/16 inch gears - kit number APN6600A.
When I took the pump out of the shipping container it was obvious someone had already tried to rebuild it. The old gears were loose in the box and I measured them before I even started on the pump. Face width of the old gears was .555/.554 - .007/.008 under the nominal 9/16 that everybody talks about. The shaft on the drive gear also measured .559 - .003 under the nominal 9/16" it is supposed to be. When the gears were placed in the housing there was a perceptible ledge were the gears sat below the top of the pump cavity. At that point I was pretty sure the rebuild kit that had been used was one of the "cheapies".
Next I had a look at the housing. The bore in the bushing was clearly off center and out of plumb. The shaft fit was reasonably tight leading me to believe that Bubba and his reamer had struck again. When I was checking the fit of the gears in the housing I had also noticed that one side of the drive gear sat considerably lower that the other. That is likely because the botched bore in the bushing caused the gear to run cocked in the pump cavity wearing into one side of the bottom and likely taking some off the wall in the process. That damage is not repairable and we'll have to wait until the pump is properly rebuilt and back in the tractor to see if it causes significant problems.
I was asked to supply the new parts for this rebuild and I purchased the kit from nnalert's - here is a picture of what I received. No indication of manufacturerer anywhere on it but FWIW it does say Made in USA on the card...
I opened it up and measured the drive shaft - .562 on the money. Both gears also measured .562 and except for the previously mentioned wear on the bottom of the pump cavity sit dead flush with the top.
Two morals to this story:[list:cbc871a4f8][*:cbc871a4f8]Botching an oil pump rebuild can and likely will cause damage to the pump housing[*:cbc871a4f8]Avoid the "cheapie" kits unless you can verify the parts are properly made. Always measure the new parts before you waste your time putting a pump together with bogus parts.[/list:u:cbc871a4f8]Tomorrow I'll put it all back together with the new parts and see what the running clearances look like. Hopefully it will provide the owner with acceptable service...
TOH
When I took the pump out of the shipping container it was obvious someone had already tried to rebuild it. The old gears were loose in the box and I measured them before I even started on the pump. Face width of the old gears was .555/.554 - .007/.008 under the nominal 9/16 that everybody talks about. The shaft on the drive gear also measured .559 - .003 under the nominal 9/16" it is supposed to be. When the gears were placed in the housing there was a perceptible ledge were the gears sat below the top of the pump cavity. At that point I was pretty sure the rebuild kit that had been used was one of the "cheapies".
Next I had a look at the housing. The bore in the bushing was clearly off center and out of plumb. The shaft fit was reasonably tight leading me to believe that Bubba and his reamer had struck again. When I was checking the fit of the gears in the housing I had also noticed that one side of the drive gear sat considerably lower that the other. That is likely because the botched bore in the bushing caused the gear to run cocked in the pump cavity wearing into one side of the bottom and likely taking some off the wall in the process. That damage is not repairable and we'll have to wait until the pump is properly rebuilt and back in the tractor to see if it causes significant problems.
I was asked to supply the new parts for this rebuild and I purchased the kit from nnalert's - here is a picture of what I received. No indication of manufacturerer anywhere on it but FWIW it does say Made in USA on the card...
I opened it up and measured the drive shaft - .562 on the money. Both gears also measured .562 and except for the previously mentioned wear on the bottom of the pump cavity sit dead flush with the top.
Two morals to this story:[list:cbc871a4f8][*:cbc871a4f8]Botching an oil pump rebuild can and likely will cause damage to the pump housing[*:cbc871a4f8]Avoid the "cheapie" kits unless you can verify the parts are properly made. Always measure the new parts before you waste your time putting a pump together with bogus parts.[/list:u:cbc871a4f8]Tomorrow I'll put it all back together with the new parts and see what the running clearances look like. Hopefully it will provide the owner with acceptable service...
TOH
:65831ff02c]Resized bore in bushing is now centered and plumb with bore in pump housing.
