Alternator fit

Wildride47 · Jan 11, 2018

I have a 1988 JD 2555 diesel and want to replace the alternator. Parts listings have a 55 and 85 amp listed. How do I know what unit is on the tractor currently? My guess for a duel battery would be 14 volt 85 amp

TractormanNC · Jan 11, 2018

If it is an open station tractor, chances are it has the 55 amp. Cab tractor will have the higher output alternator.

Wildride47 · Jan 11, 2018

It’s an open station. Is there any marking or physical difference between the two types to aid in identifying the difference? Guess the other question would be is there a risk using the 85 amp on the open station. I’d guess the risk would be boiling off the battery with the larger alt.

Lee B · Jan 11, 2018

No, no risk at all using a larger alternator for a smaller output one. The voltage regulator will output the correct charging voltage at all times - this is their only job and they do it very well for decades at a time or fail entirely. And you will notice the difference right away.

Wildride47 · Jan 11, 2018

The saddest part about this project is at the high cost of replacing this unit is they no longer come with the pulley and fan installed. I now have to figure out how to get this apart without damaging it. Sigh

Ronnie Budd · Jan 11, 2018

Just spin the nut holding the fan and pulley off with an impact wrench, then install on the new alternator and seat it with the impact. It's easy, but you'll probably need a thin wall deep socket.

Alternator fit

Wildride47

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TractormanNC

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Wildride47

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Lee B

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Wildride47

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Ronnie Budd

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