Wierd exciter

[Rattlenbang]

I'm having trouble with the exciter circuit on my alternator; it doesn't seem to have high enough voltage to tickle the thing on. The alternator isn't having any output and when I measure the exciter voltage its 2 volts lower than system voltage. The light is ok and isn't coming on because there is power there, but not enough to wake up the alternator. If I go below and short from the alternator output (battery voltage) to the exciter lead, the alternator starts. Sounds like a dodgy connection somewhere but the only circuit diagram I have is for the gas version and doesn't seem right.

Any suggestions? anyone have a diesel schematic? Is this a typical old school system where the exciter voltage goes through the charge light?

[FalcoColumbarius]

Perhaps in Engine Electrical?
Falco.

[Rattlenbang]

Got it from Big Bird, thanks!

[Rattlenbang]

Exciter circuit red herring. Alternator brush shot.

I've replaced seals on this damned thing twice and soon they crap out again. Just can't keep the oil outta the damned thing. What an ugly design. This is after half a can of brake clean.



This is the problem. Very weird to eat one with the other still good.



Now I have a dilemma: I can pick up a new one at Macs for $280 plus tax or just get some brushes for a few bucks. I had actually intended on replacing the damned oil filled vacuum pump with a VW electrical vacuum pump I have, but that means a lot of rerouting of lines and wiring in a circuit with relays and such crap, and time is dear right now. Pulling alternators on these things is such a PITA.

[Big-Bird]

For one brush to bite it...Either a stone/gravel bit got kicked into the unit or the brush was defective from day 1.

[Rattlenbang]

Well ain't that a royal PITA. I replaced that seal less than 18 months ago. No wonder oil was leaking so bad through the thing.


Picked up a replacement from Macs. Rather pay the cash than do this again.