Replaced Alternators All Smoking

[BearDLP]

Hey Y’all, had 3 consecutive alternators put in my new baby (1972 K5) and the regulator was also changed, all 3 alternators started smoking after a bit. I am clueless about mechanics but am trying to learn. Any thoughts, I’m thinking it’s a wiring issue? Do I need a new truck or just a Master Mechanic boyfriend??

 

[ashman]

Got to be a wiring issue. I'd bet that your new alternators have an internal regulator and maybe the external one is causing an issue?

 

[Wes Harden]

Do you have a volt meter? How long do it take for the alt to start smoking? As soon as battery is connected? Or after has been running for a few minutes?

 

[BearDLP]

Got to be a wiring issue. I'd bet that your new alternators have an internal regulator and maybe the external one is causing an issue?

Hmmm interesting, ok thank you, I’ll research that!

 

[BearDLP]

The last alternator replacement it started smokin bout 20 seconds after starting K5. Went from 13 amps to 16 amps almost immediately then shortly after started smoking. After everything connected, before I tried to start it, the new regulator also felt hot to the touch

 

[BearDLP]

Got to be a wiring issue. I'd bet that your new alternators have an internal regulator and maybe the external one is causing an issue?

Apparently all the new alternators I got were the 1972 externally regulated alternators, so that shouldn’t be the issue

 

[Wes Harden]

16 amps? Could be amps but I'm guessing you have a volt meter?.
On the assumption that it is 16 volts. This means the alt is "full fielded" The alternator has full current to the field windings and will go to max out put. We use full field as a test. This test is not ever done for more than a few seconds, to prevent damage.
The field current is controlled by the regulator. Either the regulator is sending full current or the wiring is bad.

The following pic represents your system. Ignore internal regulator reference.
See if you can follow your wiring and match the the picture. While doing so look at the wires for crumbling, melted, stuck together insulation. All signs of a possible problem.

 

[Wes Harden]

The F terminal is the field terminal.

 

[BearDLP]

16 amps? Could be amps but I'm guessing you have a volt meter?.
On the assumption that it is 16 volts. This means the alt is "full fielded" The alternator has full current to the field windings and will go to max out put. We use full field as a test. This test is not ever done for more than a few seconds, to prevent damage.
The field current is controlled by the regulator. Either the regulator is sending full current or the wiring is bad.

The following pic represents your system. Ignore internal regulator reference.
See if you can follow your wiring and match the the picture. While doing so look at the wires for crumbling, melted, stuck together insulation. All signs of a possible problem.

View attachment 392614

Many thanks, Wes Harden, I’ll give it a shot!

 

[1-ton]

Sounds like to me there is a hot wire grounded out somewhere. Check the wires going down to the starter in the area where they come close to the exhaust system, and where they connect to the starter solonoid.

 

[BearDLP]

Thank you appreciate your input!

 

[sponsoredbydad]

So did this ever get resolved? What did you find?