Replacement alternator for New Holland 3930 - confused about part number

[Tangoddess]

Hello,

I need to replace the ALTERNATOR in my New Holland 3930 tractor. I have tried two brand new 950CCA Interstate batteries and both of them have lost cells, i.e. they are losing charging power I believe, after few weeks of use each.

Luckily I replaced one under warranty.

I was told the problem is the alternator, I already tightened the alternator belt.

I visited the New Holland online parts store Official New Holland Online Parts Store and Online Parts Catalog for New Holland and Ford Tractors., and to my limited understanding, it gives me 2 different part numbers for the alternator

1) 82857207 - Assy 45 Amp includes Ref 1A thru

or

2) 81863039 - Assy 55Amp L/Cab


Does this mean that 81863039 is for the model with the L/Cab? whatever that means?

It seems like the different is that one is 45amp and the other is 55amp?

Which one would be the correct one for my tractor? It does NOT have a cab. Unfortunately there is nothing written on the existing alternator

It looks like it may be the same part just different model numbrs? I am checking on tractorpartsa....com and their part number 111070 says it replaces both of these models?

Thanks!!

 

[joecdeere]

L/cab means less cab, A tractor with a cab will have A/c and more lights so needing a larger alternator. I'd be taking that old one to a local starter / alternator repair place before I gave New Holland several hundred dollars

 

[3930dave]

I'll second going to an electrical rebuilder.

Any decent alternator shop can rebuild pretty much anything, usually for a good price - cash in-hand can help on pricing.

Rgds, D.

 

[Phillip w]

I'd pull that alternator and take it to Napa or O'Reillys and have it tested. A loose connection can cause you not to charge and it isn't the alternator that is causing the problem. If it is the alternator, I'd try to find somwine to rebuild it. By the way, have you try to jump start it? If you have and you accidentally sent a reversed bias voltage through the system, that tend to blow the diodes in.the alternator and your alternator is done

 

[Tangoddess]

Hello all

Thank you for your advice.

It seems that a new alternator, ordered online from tractorpartsa... with shipping will come to about $100.

I am wondering if this is more convenient than having it fixed, which may cost at least $50 or more, and may have a longer wait in case parts are needed?

I ain't sure how much it could cost to have an alternator fixed

What do you all feel?

 

[hosspuller]

I would check the voltage when the tractor is running... 13.5 to 25 volts means the alternator is working. If not then get it tested before replacing. A wiring fault or relay not working can keep a good unit from charging the battery.

 

[hosspuller]

One more thought. Do you have the battery secured in the tractor? a battery laying loose in a tray gets a lot of vibration and movement... enough to break plates loose and short the cell.

 

[Tangoddess]

I forgot to add, that once, the tractor was jump started with a vehicle.

Since we got the tractor, we bought a brand new 950CCA interstate battery and installed it, it worked fine, then after a month, it did not start up, we tested the voltage using the $10 multimeter and it read 12 volts or so....so we went to the dealer and they replaced the battery with a new battery.
Now even the replacement seems to be losing cells, it does not keep charge and when we charge it on a battery charger, the maximum voltage it seems to reach is about 12.7 volts on the battery charger...
The person who came to change out the hoses (independent, not through the dealer) checked the battery and alternator, and said the alternator was bad...he checked it with some sort of instrument like a multimeter.
So we feel the alternator may be bad....we bought the tractor used...and it is a 1999 tractor or maybe a few years older?

 

[3930dave]

That pricing doesn't seem bad, at a glance. Then again, Canadian pricing tends to me much higher on most things, so I'm probably out of touch on TX pricing.....

One advantage to taking the alternator to a rebuilder is they should be able to spin it up on their own test-bench for eval. If mice, or just time, have taken their toll on the tractor wiring, it may not (only) be the alternator that is the issue.

Up here, auto parts stores often can test car and truck alternators, but AFAIK, not tractor alternators.

Rgds, D.

 

[Tangoddess]

How hard or easy is it to get the alternator out?

We have many tools, but are deficient/lacking in the knowledge and intellect and ability departments related to tractors and Agri equipment