The alternator on my 1980 455 cid olds has smoked three diode packs in a
Diode smoke might not cause cancer but it's pretty irritating in its way.
Before this the alternator (AC Delco 82 Amps) has worked fine for over
Extremely rainy day. Car running at 600rpm at a parking lot. (waiting for
the rain to stop)
Suddenly "gen-light" turns on. I stop the engine wait a while and the
restart it. Gen-light still on.
Hood up checked the v-belt and wiring. Nothing wrong there. Checked the
output voltage. Alternator doesn't charge.
Alternator off the car -> opened dried and tested on the bench. Diode pack
crashed for "some reason".
Installed a new diode pack and alternator gives 14.2V and seems alright to
me. Case closed -> drive.
After about 300 miles of driving the gen light strikes again.
It was fine on the freeway, but after cruising a little on the city it
No smoke or traces of short circuiting. Alternator not overhot. Nothing out
of the ordinary except the gen light is on again. Tested the charge ->
none. After kicking and swearing I take the alternator off.
This time change the regulator, coal sets, bearings and of course the diode
Test on the bench -> fine. Hook the alternator to car and continue driving.
After only 5 miles the gen light is on again. This happened right after a
steep 90 degrees turn to left. I haven't even opened the alternator yet
because I _know_
what is broken...the diode pack.
Now here's the tricky part: Why? What tf happened? car was running fine
with this alternator for years.
I have _never_
winessed a car killing alternators like this. If there was a
short circuit somewhere it would kill the alternator instantly and not
after some miles(?). All the cases when the alternator broke are identical
in the way that engine was running. I think that I replaced enough parts
after the second crash that "the fault is inside the alternator" theory
doesn't hold. I can borrow an alternator from a friend but I doubt that it
would get the same treatment. After all here in Finland the AC Delco
equivalent diode pack costs app. $30 and factory remanufactured alternators
cost 150 to 250 dollars it's not a funny game to spend money on own
stupidity. It's the last straw to put a different alternator to the car and
see (and smell) what happens. Can an "almost short circuit" cause this? I
mean if there's a cable (to the starter for example) that sometimes when
the car and engine shakes short circuits to the engine and ground. I
imagine this would kill the diode pack? Shouldn't it also kill the battery?
The battery doesn't drain when the car is not running. After two days the
battery still gives 12.4V. I haven't done _any_
electrical jobs on the car
just before this occured, I have just driven the car. I have a feeling that
the fault has something to do with movement of the engine and the
wires...but I have a lot of feelings and they are not always true ;).
Help...Any ideas are welcome. I wanna get the car running again. Then I can
give time to the other problems on the car...;)
Thanks in advance.
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