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Cummins nh220

kiwi komatsu ยท 2023-07-24 03:49

Appreciate help here I bought a 1980s Komatsu D65e-6.with a Cummins NH220 to restore. After sitting for a year i replaced belts and hoses. On start up heard hi pitch squeal typical of a ball race bearing running, then after aboutv3 minutes the new alternator & fuel pump belt melted. Pump pulley was very hot to touch. Any clues as to bearing location? I guess radiator is coming out again. Suggestions appreciated

Replies6
  1. #1kshansen2023-07-24 07:44

    First thing I would suspect is the alternator had a bearing failure and caused the belt to fail. Not familiar with the NH220 as used in a D65e-6 but if it is about the same as any other NH Cummins I have worked on what you are calling a "fuel pump belt" is more or less an accessory drive pulley on the left side of the front cover. A picture or two would clear that up but being a new poster I believe you have to post something like 3 posts before adding picture. So just post a few time giving us some background on your self and what plans you have for this Komatsu.

  2. #2kiwi komatsu2023-07-24 15:36

    Thanks for the advice. Indeed I'll go check tge alternator as that's much easier to access. The thing that threw me was that it's the accessory pulley on the left that became really hit, not the alternator pulley ,which was cool, but maybe the slippage occurred around the accessory pulley causing heat. Will advise. Peter

  3. #3kiwi komatsu2023-07-29 22:42

    Thank you so much. Diagnosis was spot on. Alternator bearings had siezed. Belt had melted at the accessory drive pulley causing it to heat up, and generate a lot if smoke. Much easier to fix an alternator than the PT fuel pump. Peter

  4. #4Shimmy12023-07-30 00:07

    That pulley is driven internally by the engine gear train. I'm curious on how things are set up on this, normally the alternator is on the right side, driven by the crank pulley. Your water pump is in the center of the engine up front, there will be a belt driving it.

  5. #5kiwi komatsu2023-07-30 00:16
  6. #6kiwi komatsu2023-07-30 00:19

    Photo (left side) shows how Komatsu set up the Cummins NH220. Alternator removed, driven by a single belt from accessory pulley also drives the water pump. Blower fan is driven by a pair of heavy belts with an adjustment idler accessed on right hand side (with skinned knuckles).