This week's project: Kubota Alternator woes

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This week's project: Kubota Alternator woes

Postby Oro » Mon Jun 08, 2020 6:31 pm

The alternator on my neighbor's tractor is acting up. I owe him a big favor* so I said I would take care of it. He got me out of a jamb.

He had the ignition switch apart as he thought that was the issue at first - it wouldn't turn off one day. I quickly realized it was the alternator as the battery was dead and the alternator had no output. I pulled off the VR/brushes, and the brushes were quite good. The tractor is a small Kubota BX1850d. It's about 11/12 years old and well used but not trashed, did not find an hour meter on it anywhere. Alternator is a nippondenso 101211-1440, nothing weird here. I suspected the VR was shot so I got another one and no joy. Oops, should have dug deeper. I did put some emery cloth to the slip rings to clean them up, no issue there. belt had good tension when testing.

If I take a meter and ground to chassis then probe each of the three output connectors, I get basically nothing anywhere - a few mV max anywhere. Should I just get a new alternator? Could the stator/rotor or something be cracked, or possibly the brushes failed internally? (they ride in a molded case, can't follow the wire connector - the new VR came w/o brushes so I was using the old ones).

Appreciate any next diagnostic steps or tips. An internet search about proper diagnosis was fruitless, oddly.



* Big favor: I spilled five quarts of used motor oil in the back of a customer's Tahoe. Oh god. He owns a carpet cleaning/restoration business and he got it looking very nice - a pretty big job.
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Re: This week's project: Kubota Alternator woes

Postby RickP » Mon Jun 08, 2020 8:55 pm

Oro wrote:
* Big favor: I spilled five quarts of used motor oil in the back of a customer's Tahoe. Oh god. He owns a carpet cleaning/restoration business and he got it looking very nice - a pretty big job.


My dad had a Pinto wagon in the early 80's and he took it to a shop for a brake job. Someone at the shop thought it was a good idea to drive it to the junkyard to pick up a used transmission for another job. The transmission apparently still had gear oil in it and spilled all over the cargo area. That thing smelled like gear oil for the rest of the time he owned it.
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