Maybe the last charging system question

[Rrent]

Both alternators rebuilt
When engine is revved or even driven at 55mph the #2 alternator idiot light flashes
Gauge good
gauge on battery good -I had someone watch it while it revved/made the light flash
First time it happened I tighten the belt, second time tighten it a little more.
Upon turn the truck off battery indicated just over 13 volts
Is there such a thing as the belt being too tight?

 

[WWRD99]

Both alternators rebuilt
When engine is revved or even driven at 55mph the #2 alternator idiot light flashes
Gauge good
gauge on battery good -I had someone watch it while it revved/made the light flash
First time it happened I tighten the belt, second time tighten it a little more.
Upon turn the truck off battery indicated just over 13 volts
Is there such a thing as the belt being too tight?View attachment 852058View attachment 852059View attachment 852060View attachment 852061

I think I have a grasp of what you're going through since I just did the same thing with alternators and belts...you can get the belts to tight as in they will wipe out the bearing in the new alternators and possibly wear out the pulley grooves...there is a belt gauge out there for tightness that measures belt deflection to indicate proper belt tightness but I only use that on certain timing belt setups....it sounds like you have it ok since the light isn't on anymore after it was slipping to not anymore...one thing I look at while it's running is if the belt moves up and down more than a inch or so in between the pulleys...It is going to deflect so the fine point is if you can hear it vibrate like a guitar string then it is to loose...if not it should be ok...did you change the belts?

 

[Rrent]

I think I have a grasp of what you're going through since I just did the same thing with alternators and belts...you can get the belts to tight as in they will wipe out the bearing in the new alternators and possibly wear out the pulley grooves...there is a belt gauge out there for tightness that measures belt deflection to indicate proper belt tightness but I only use that on certain timing belt setups....it sounds like you have it ok since the light isn't on anymore after it was slipping to not anymore...one thing I look at while it's running is if the belt moves up and down more than a inch or so in between the pulleys...It is going to deflect so the fine point is if you can hear it vibrate like a guitar string then it is to loose...if not it should be ok...did you change the belts?

Yep new belts, batteries, starter (just for grins).

 

[frank8003]

Yep new belts, batteries, starter (just for grins).

Does that have a belt tensioner?

 

[Rrent]

Both alternators rebuilt
When engine is revved or even driven at 55mph the #2 alternator idiot light flashes
Gauge good
gauge on battery good -I had someone watch it while it revved/made the light flash
First time it happened I tighten the belt, second time tighten it a little more.
Upon turn the truck off battery indicated just over 13 volts
Is there such a thing as the belt being too tight?View attachment 852058View attachment 852059View attachment 852060View attachment 852061

I did pull an old capacitor off if the back of this alternator- any chance that plays in?

 

[WWRD99]

I did pull an old capacitor off if the back of this alternator- any chance that plays in?View attachment 852074

If I remember right that is the capacitor that will knock down voltage spikes on the passenger side alternator...I don't think that's much of an issue unless you still have the military radio in the truck still...should lower radio interference.

Sent from my SM-G955U using Tapatalk

 

[Rrent]

Does that have a belt tensioner?

No

 

[Rrent]

I minimized the winking of the light by loosing the belt until it was not charging and then tightening just enough to get it working. At this point I’m not 100% sure if it’s a problem or my ocd….

 

[Curtisje]

Damn. I'm stumped.

Your referring to a suppressor that you removed from the back of the #2 Alt, not a capacitor. I mix up the terms myself quite a bit.

I've studied the wiring diagrams and I can't figure it out.

Maybe a bad ground on the #2 Alt relay???

You could swap out alternator positions... move the drivers side to the passenger side and vice versa... see if you still have the problem.

Good luck.

 

[Rrent]

Damn. I'm stumped.

Your referring to a suppressor that you removed from the back of the #2 Alt, not a capacitor. I mix up the terms myself quite a bit.

I've studied the wiring diagrams and I can't figure it out.

Maybe a bad ground on the #2 Alt relay???

You could swap out alternator positions... move the drivers side to the passenger side and vice versa... see if you still have the problem.

Good luck.

I’ll probably swap alternators, but will check the relay - where is it?

 

[Curtisje]

I’ll probably swap alternators, but will check the relay - where is it?

I think the relay is located under the dash next to the starter relay.

 

[Rrent]

I think the relay is located under the dash next to the starter relay.

I’ll research it this evening. I’ve done many projects (1 year ready to drive) / and I’m there now - Thanks -R

 

[Curtisje]

I’ll research it this evening. I’ve done many projects (1 year ready to drive) / and I’m there now - Thanks -R

TM 9-2320-289-20p, page 33-1, figure 32. Just to the left of the stater relay in the picture there are 2 40amp relays, one for the #2 alt and one for the voltmeter. They are not mentioned on this page but can be seen. Dashed outlines. I put a red arrow in there.

 

[MarcusOReallyus]

Your referring to a suppressor that you removed from the back of the #2 Alt, not a capacitor. I mix up the terms myself quite a bit.

That's easy to do, because they are interchangeable.

It's a capacitor. It's being used there to suppress radio noise, so yes, it's called a suppressor. In this application, capacitor = suppressor. Capacitor is what it IS, suppressor is what it DOES.

And to answer the earlier question, no, this is NOT the source of the problem.

As already mentioned, the ground is always a good place to look, and the relays are a good place to look.

Nope, it's not OCD, it's a real problem.

 

[Rrent]

That's easy to do, because they are interchangeable.

It's a capacitor. It's being used there to suppress radio noise, so yes, it's called a suppressor. In this application, capacitor = suppressor. Capacitor is what it IS, suppressor is what it DOES.

And to answer the earlier question, no, this is NOT the source of the problem.

As already mentioned, the ground is always a good place to look, and the relays are a good place to look.

Nope, it's not OCD, it's a real problem.

“Nope, it's not OCD, it's a real problem.”
- so a piece of duct tape cut round and put over the light might not be a good “repair”?

 

[Rrent]

Both alternators rebuilt
When engine is revved or even driven at 55mph the #2 alternator idiot light flashes
Gauge good
gauge on battery good -I had someone watch it while it revved/made the light flash
First time it happened I tighten the belt, second time tighten it a little more.
Upon turn the truck off battery indicated just over 13 volts
Is there such a thing as the belt being too tight?View attachment 852058View attachment 852059View attachment 852060View attachment 852061

As I’m pondering the problem. I put the rebuilt #2 alt in a couple of days before Thanksgiving (Tuesday), then changed the starter (Sunday) noticed this light situation yesterday. Starter was a pretty straight forward out with old/in with new. I most likely didn’t rev the motor and definitely didn’t drive the truck during this Tuesday to Tuesday timeframe.
Is there anything I might have done when installing the starter? So, I’m not sure if the problem just went unnoticed.

 

[Keith_J]

Bench test of alternators is possible. All you need is a decent battery, the 2 pin connector and a light bulb. Ring terminals and a few lengths of wire complete the circuit, then a sanding disc rubber backed on a drill to spin the alternator. You should see the light illuminate without spinning and the light go out once you get 14 volts output. Thin wires help get the output, 18 gauge is perfect. Measure voltage at the alternator.
I've spun the alternator with a socket in my electric impact wrench, it free wheels 1800 RPM, perfect. You won't get 100 amps with this test, that takes belt slipping torque. But a dead alternator won't output anything.

High output difficulties point to regulator or slip ring connection problems

 

[MarcusOReallyus]

“Nope, it's not OCD, it's a real problem.”
- so a piece of duct tape cut round and put over the light might not be a good “repair”?

I'm thinking maybe not.....




BTW, there is a sticky at the top of the forum about tesing alternators on the vehicle. If you haven't given it a look yet, maybe it's time.

 

[WWRD99]

As I’m pondering the problem. I put the rebuilt #2 alt in a couple of days before Thanksgiving (Tuesday), then changed the starter (Sunday) noticed this light situation yesterday. Starter was a pretty straight forward out with old/in with new. I most likely didn’t rev the motor and definitely didn’t drive the truck during this Tuesday to Tuesday timeframe.
Is there anything I might have done when installing the starter? So, I’m not sure if the problem just went unnoticed.

Have you charged the new batteries you put in? I know it sounds silly but I always do...a nice low 2-6 amp for a few days just to make sure they're completely topped off...got the OCD a little...are the battery cables and ends in good shape? Like not crushed together and such. Also is the light on anymore since you got the belt tight? I had a bunch of rust on the other pulleys too...might see if the belts getting chewed up from that as well...I sanded them all and replaced the lower crank pulley.

Sent from my SM-G955U using Tapatalk

 

[Rrent]

Have you charged the new batteries you put in? I know it sounds silly but I always do...a nice low 2-6 amp for a few days just to make sure they're completely topped off...got the OCD a little...are the battery cables and ends in good shape? Like not crushed together and such. Also is the light on anymore since you got the belt tight? I had a bunch of rust on the other pulleys too...might see if the belts getting chewed up from that as well...I sanded them all and replaced the lower crank pulley.

Sent from my SM-G955U using Tapatalk

Batteries tested - fully charged. The light was more of a flicker than full on - like when the key is turn on waiting for the glow plug light.
I may have “solved” the problem - I put an aftermarket alternator in the #2 slot and no light flicker. This all started with an .83 parasitic drain that lessen to a .03 with just a new battery. It is still at .03