89 LT TRK alternator

[larryc]

My 89 light truck has burnt out two alternators within a week.
the first one was good till the amp guage showed about 4 amps while running, I shut it off without noticing anything. The next morning the battery was dead and wouldn't take a charge. So we took a used alternator out of a non working truck of the same year make etc. and put it in along with a fully charged battery, pulled the cable while it was running to check the alt. and it was good.
The charge guage went to 16 amps, or thereabouts, and stayed there even when the battery light came on a few days later.
I am at a loss as to why that would happen unless I inadvertantly got ahold of two bad alternators in a row.
Any ideas?
Thanks.

 

[nomercyf-150]

My 89 light truck has burnt out two alternators within a week.
the first one was good till the amp guage showed about 4 amps while running, I shut it off without noticing anything. The next morning the battery was dead and wouldn't take a charge. So we took a used alternator out of a non working truck of the same year make etc. and put it in along with a fully charged battery, pulled the cable while it was running to check the alt. and it was good.
The charge guage went to 16 amps, or thereabouts, and stayed there even when the battery light came on a few days later.
I am at a loss as to why that would happen unless I inadvertantly got ahold of two bad alternators in a row.
Any ideas?
Thanks.

Hello i would would say try checking the voltage regulator. i had a similiar problem in my 78 and i ended buying to bad regulators in a row and thought it was the alternator and went through about three of them. Goodluck

 

[larryc]

Hello i would would say try checking the voltage regulator. i had a similiar problem in my 78 and i ended buying to bad regulators in a row and thought it was the alternator and went through about three of them. Goodluck

AFAIK, the 89 has internal regulators.
External would be nice tho...
Thanks anyway.

 

[Shadow_D]

that was my thought as well