Alternator Quit Charging after 5 minutes of Running

[RTR]

When I started the 8n up for the first time since taking it apart for "restoration" the alternator was showing charging on the ammeter, then all of a sudden I heard a noise and the alternator fan started hitting the upper alternator bracket enough to go "ding-ding-ding...". It was about that time I noticed that it quit charging and hasn't shown it was charging since. I would check it with a multi meter but mine bit the dust a couple weeks ago. This probably happened after running for about 5 minutes.

Not sure if it is related or not with fan hitting, but at first the fan wasn't hitting. Alternator worked before I tore into the tractor. All wiring is new. I removed alternator pulley and painted the whole unit.

This post was edited by RTR on 11/01/2023 at 12:40 pm.

 

[JMOR]

Did you verify that the nut on alternator shaft was properly tightened?

 

[RTR]

(quoted from post at 00:53:14 11/02/23) Did you verify that the nut on alternator shaft was properly tightened?

have not and thought about this , but would it affect the charging? Looks like everything is spinning. Is there a way to tell, ie torque?

This post was edited by RTR on 11/01/2023 at 03:19 pm.

 

[JMOR]

(quoted from post at 18:18:28 11/01/23)

(quoted from post at 00:53:14 11/02/23) Did you verify that the nut on alternator shaft was properly tightened?

have not and thought about this , but would it affect the charging? Looks like everything is spinning. Is there a way to tell, ie torque?

This post was edited by RTR on 11/01/2023 at 03:19 pm.

ould be the pulley/fan spin, but not alternator shaft/rotor. And that would affect charging.

 

[used red MN]

Got a 1/2 inch air impact? Put it on there and give it a
couple quick ..ugga-guggas.. Oh no, there goes the
paint. Well you probably do not want to do that. First
off grab a 15/16 inch box end stick it on there and grab
the belt and squeeze it together and tighten it what it
will allow, that should be tight enough to drive the
alternator. If that works they used to have a spot for an
Allen wrench in the end, you can hold it that way and
see if it tighten more. Actually the best way to tighten
them is with an impact.

 

[Eman85]

Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

 

[RTR]

(quoted from post at 05:32:22 11/02/23) Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

I just tried it and it was loose. Got it tight by using an Allen wrench in the middle and a crescent wrench on the nut. Tightened half a round and the fan isn t loose any more. The alternator still isn t charging. Found a meter and verified that at the battery.

Is there a way to test the alternator or could it be a ground issue?

 

[RTR]

(quoted from post at 05:32:22 11/02/23) Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

I just tried it and it was loose. Got it tight by using an Allen wrench in the middle and a crescent wrench on the nut. Tightened half a round and the fan isn t loose any more. The alternator still isn t charging. Found a meter and verified that at the battery.

Is there a way to test the alternator or could it be a ground issue?

 

[Jim.ME]

(quoted from post at 23:01:52 11/01/23)

(quoted from post at 05:32:22 11/02/23) Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

I just tried it and it was loose. Got it tight by using an Allen wrench in the middle and a crescent wrench on the nut. Tightened half a round and the fan isn t loose any more. The alternator still isn t charging. Found a meter and verified that at the battery.

Is there a way to test the alternator or could it be a ground issue?

I doubt it is a ground issue, but pretty easy to use a jumper wire between the alternator case ground and the battery to check.

One or three wire? Does it have the ''D'' Hole in the back with a tab visible inside? With a three wire that has the tab you can use a screwdriver to short the tab to ground, with the engine running at least half throttle, and the alternator should jump to full output.

 

[RTR]

(quoted from post at 15:30:55 11/02/23)

(quoted from post at 23:01:52 11/01/23)

(quoted from post at 05:32:22 11/02/23) Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

I just tried it and it was loose. Got it tight by using an Allen wrench in the middle and a crescent wrench on the nut. Tightened half a round and the fan isn t loose any more. The alternator still isn t charging. Found a meter and verified that at the battery.

Is there a way to test the alternator or could it be a ground issue?

It is a 1-wire delco.


I doubt it is a ground issue, but pretty easy to use a jumper wire between the alternator case ground and the battery to check.

One or three wire? Does it have the ''D'' Hole in the back with a tab visible inside? With a three wire that has the tab you can use a screwdriver to short the tab to ground, with the engine running at least half throttle, and the alternator should jump to full output.

 

[Jim.ME]

[u:a722493e59]If[/u:a722493e59] there is a tab visible inside the ''D'' hole, the arrow points to, you may get full output if you use a screwdriver to short the tab to ground (the alternator case around the hole). Not all regulators have the tab.

I would flip your alternator adjusting bracket over to get it further from the fan. You picture shows the top of the steel above the slot is thinner than the lower side of the slot.

 

[RTR]

(quoted from post at 17:47:54 11/02/23)

I actually noticed that after I posted this picture and plant to flip it. I bet that'll fix the rubbing issue. For the alternator, if I short it to ground and it starts charging, does that tell me the regulator is bad, therefore needing to replace the alternator?

 

[Eman85]

(quoted from post at 20:01:52 11/01/23)

(quoted from post at 05:32:22 11/02/23) Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

I just tried it and it was loose. Got it tight by using an Allen wrench in the middle and a crescent wrench on the nut. Tightened half a round and the fan isn t loose any more. The alternator still isn t charging. Found a meter and verified that at the battery.

Is there a way to test the alternator or could it be a ground issue?

Hook the meter directly to the alternator with the tractor off and see if you have voltage there, then start and see what you get at the alternator.

 

[Bruce(OR)]

All that shiny fresh new paint.
The ground is where?
On top of the paint.
I understand.
Run a jumper wire from the alt case to ground after you get another DVOM.
Base charging should be roughly 14.2 volts.
I believe the allowable range is 13.8 to 15 volts.
Shorting out the tab in the rear is cheap fun for max output both volts and amps.
I believe I saw one hit 27 volts and about 200 amps once.

 

[Hobo,NC]

There is a bunch of info on a GM 10SI alt out there for a 3 wire I am not sure about a one wire. GM did provide a nice ground point but its rarely used. And the ammeter verses voltmeter issue if you had trashed that not of much use dash mounted ammeter you could have had a useful voltmeter mounted right in front of you.

Ammeter lubbers this is your chance dream sum'N up : )

There are a few shadtree ways to check that alt but that is to insure it will get you home, you are at home so you need a Voltmeter.

I also have my doubts your alt has the correct alt pulley the correct pulley # is 98NAA5825. Live and learn now would be a good time to correct that.

 

[RTR]

(quoted from post at 21:16:48 11/02/23)

(quoted from post at 20:01:52 11/01/23)

(quoted from post at 05:32:22 11/02/23) Many GM alternators have a hex broached in the shaft to hold with an allen wrench.

I just tried it and it was loose. Got it tight by using an Allen wrench in the middle and a crescent wrench on the nut. Tightened half a round and the fan isn t loose any more. The alternator still isn t charging. Found a meter and verified that at the battery.

Is there a way to test the alternator or could it be a ground issue?

Hook the meter directly to the alternator with the tractor off and see if you have voltage there, then start and see what you get at the alternator.

No terminal on that spot. New alternator sold led the problem. Guess it was just coincidence that it died.