Alternator question.....

[alpinecrick]

1996 K1500 5.7 w/105 amp alternator.

After driving a while with the motor fully hot, especially now that it's a bit warmer outside, my volt meter gauge drops quite a bit below the 14v mark, getting close to the next large hashmark on the volt meter. It was doing this last night, and when I turned on the headlights it dropped further on the gauge. I have not put the multimeter on it when it's reading low with a hot engine.

This morning, with the truck outside and temps in the high 30's I start the truck and the volt meter gauge reads a full 14 volts, my multimeter reads output of 14.6, and with the engine off the battery reads 12.6 volts on the multimeter.

My experience has been a alternator eithers works fine or it quits working period.
Usually a regulator or rectifier just quits at once rather than a slow death in my experience.

Could the brushes be wearing out?

 

[AuroraGirl]

14.6 seems a tad high, like boil a battery in right conditions or etc. 14.4 would be more comfortable

 

[alpinecrick]

14.6 seems a tad high, like boil a battery in right conditions or etc. 14.4 would be more comfortable

I measured the voltage right after I started it, usually they will read a bit higher when cold?

 

[454cid]

1996 K1500 5.7 w/105 amp alternator.

After driving a while with the motor fully hot, especially now that it's a bit warmer outside, my volt meter gauge drops quite a bit below the 14v mark, getting close to the next large hashmark on the volt meter. It was doing this last night, and when I turned on the headlights it dropped further on the gauge. I have not put the multimeter on it when it's reading low with a hot engine.

This morning, with the truck outside and temps in the high 30's I start the truck and the volt meter gauge reads a full 14 volts, my multimeter reads output of 14.6, and with the engine off the battery reads 12.6 volts on the multimeter.

My experience has been a alternator eithers works fine or it quits working period.
Usually a regulator or rectifier just quits at once rather than a slow death in my experience.

Could the brushes be wearing out?

That sounds more like a gauge/wiring issue than an actual charging problem, to me. My gauge doesn't always read where it should either. I think your readings at the battery sound fine.

 

[884x4310ci]

I would try to recreate the problem. And then test with a multimeter and see where your at?

 

[alpinecrick]

That sounds more like a gauge/wiring issue than an actual charging problem, to me. My gauge doesn't always read where it should either. I think your readings at the battery sound fine.

I pulled the alternator this morning and brushes are good,, battery connections seem good. I just finished driving it around and it now reads 13.9 on my multimeter (instead of 14.6+ on cold start) and the volt meter gauge has dropped. Seems as though when the alternator gets hot in the engine compartment it reduces the output.

 

[alpinecrick]

So this begs my next question........

I have CS144 that checks out good on the parts store bench tester, but I need the connector-adapter from the square plug of the CS144 to the oval plug that's on the truck that is used for the 105 amp alternators (CS130 ?). I know they make them but didn't find any that I can tell for sure will work. Anybody have any links?

 

[F4U-1A]

Do you have the skill set to cut and spice? That would be my route.

 

[454cid]

I wonder if you could buy the right plug from Rockauto, or a salvage yard and just swap the plastic housing, using your original pins.

 

[alpinecrick]

I wonder if you could buy the right plug from Rockauto, or a salvage yard and just swap the plastic housing, using your original pins.

Do you know if the CS144 has one wire coming out of the connector like the 105 amp alternators do?