Blowing Drivers Alternator every couple of days?

[35Z-SGM]

Help, I have been rebuilding my alternator every couple of days and don't know what is causing them to go out. The truck is currently in the body shop so recommendations will not have feedback until I get the truck back.

Symptoms: Starts and operates with all meter readings at appropriate levels. This is good for one to two days and then my drivers side alternator will go out. Usually the voltage regulator is bad but I have also had bad rectifiers as well.

When it goes out I will get a spike in voltage as shown on the voltmeter.

What do you think?
Bad repair parts on the alternator.
Battery issues.
Other.

Your thoughts are appreciated.
Thanks!

 

[MarcusOReallyus]

Hmmm. That's a tough one. You might have a wire somewhere that has exposed conductors which is shorting once in a while, due to vibration.

Might be a very marginal fusible link. Can't hurt to give those a look. AutoZone will test your batteries for free. Can't hurt.

 

[WWRD99]

What kind of batteries are they? The 6t? or a car style replacement? Are they charged up completely? It does sound like a wire is not right as well like shorting out.

 

[Tow4]

Sounds like a load dump. If the alternator is operating and the output is disconnected from the load, the voltage spikes will eventually cause the regulator to fail. Connection problems can be inside the alternator also, so make sure your connections are tight and correct when you rebuild the alternator. A high charging load will cause the rectifier to fail. Alternators are not designed to carry a large percentage of their rated capacity at low rpms.

At idle, if you have a high load coming on periodically like the glow plugs, you will see the volt meter move (because the alternator output can't meet the load demand at low rpm) and hear the engine speed slow down. If you are driving, the rpm change may not be noticeable and the voltage will probably be stable. I wouldn't expect a problem at highway speed unless the alternator is at full output a lot.

 

[Curtisje]

I had a problem a while back where my alts were blowing as soon as I hooked up the batteries. Long story short... a pack rat had chewed the 24v hot wire to the starter and it was shorting to the frame. This smoked my alternators and some fusible links... a few times before I found the short.

Good luck.

 

[Mullaney]

I had a problem a while back where my alts were blowing as soon as I hooked up the batteries. Long story short... a pack rat had chewed the 24v hot wire to the starter and it was shorting to the frame. This smoked my alternators and some fusible links... a few times before I found the short.

Good luck.

.
Ouch.
That was an expensive learning experience!