1972 4000 alternator

JDfan

Member
I purchased a 1972 4000 with 11k hours last fall. I have been working on the wiring. When someone replaced the alternator, they cut off the O-4 and PU-3 wires that attach to the alternator. These wires both run to the light on the dash. I am not sure which wire connects to which spade on it or for some reason neither can/should be attached to it, or why they did this. Any help would be appreciated. Thanks, John
mvphoto102971.jpg


mvphoto102972.jpg


mvphoto102973.jpg
 
The blinding cap on the 1 and 2 spade terminals is an indication it is most likely a one wire alternator, and with a one wire alternator those terminals do not get connected. The one wire does not need to be excited by an external source, so the indicator light is not needed to start the alternator charging. Did you use a voltmeter to check to see if it was charging?

Looking at the parts catalog Motorola and Delco alternators were used. Your tractor may have had either brand originally, there are serial number breaks shown in the parts catalog. Both brands used 3 wires, so the one wire, you have, is not an OEM type replacement. You could take it somewhere and have it tested if you don't know if it works. Some of the one wire alternators can work an indicator light, some won't.

This post was edited by Jim.ME on 03/01/2023 at 02:01 pm.
 
Thank you for the information. I am pretty sure it works, but will check it. I was just hoping to have the indicator light working.
 
The last Delco alternator I repaired I asked for the original two wire voltage regulator to maintain dash light. Gen shop said he
was out of them and only had the one wire self exciting regulators on hand. When I told him why I wanted the other he informed me
the gen. / charge light could still be connected to the one wire regulator terminals and dash light would still work. The self
excited regulator was a bit more money but, when wired to the dash light it still worked. Pull the rubber plug and connect your
original voltage regulator wires and see if it will work. Mine did!
The Delco alternator was an after thought repair option only. The 4000 / 4020 were never factory built / produced with a Delco
alternator, just Motorola's. The Delco was a repair option only. They are a cheap fix. Only thing good about them they are cheap
and anybody with a nut drive and ohm meter can repair them. The Motorola was a very good alternator but became expensive to repair.
My restored 2520 is going to have an 70 amp Motorola and will look original.
 
With due respect, WTW, but the experience I've had
with Motorola alternators is not good. The tiler
who had the shed across the road, had 2 Ford back
hoes with them on & his tiling machine had a Moto
on it.
Ended up having to put Delcos on all of them after
he spent considerable time & money on them. I could
never figure why the Ford back hoes didn't come with
Ford alternators.

The one landlord who worked for Deere up in Moline
had a 2010 with a Moto alternator which caused
trouble all the time. I asked him why they put the
Motos on some equipment, & he said the company saved
$.28 on each unit VS. Delco.
JIm
 
Another thing to watch when replacing a Delco &
maybe others as well is belt alignment. Nephew
got a 4430 & I looked at the alignment---a full
belt width off. Probably the PO had replaced the
alternator with one from an auto parts store &
used the pulley that cane with it.
Jim
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top