By the way, my numbers and theory may not be exact on my "dead cell" guess.  I think it's more complicated than that  But, still, I would not replace an alternator if the battery is no good.  You just don't know what's what.

Early Z's have an external voltage regulator.......280's have an internal voltage regulator. You can have a good alternator and a bad voltage regulator. A bad battery wouldn't stress an alternator, it would take 14 volts and not charge.......no stress on the alternator.

I got rid of the external voltage regulator after one failed on my 260 and the battery blew eating through the wheel well.  This is a ZSpecialties 125 amp alternator with internal voltage regulator, i got it about 7 years ago and have put about 5K miles on it.

 

Not sure if it's related because it had rained and the connections may have been wet but my headlights were flickering, I have Dave Irwin's headlight harness that runs off the battery.

 

http://www.datsunstore.com/high-output-alternator-p-1.html

Edited April 27, 201510 yr by gogriz91

 

Early Z's have an external voltage regulator.......280's have an internal voltage regulator. You can have a good alternator and a bad voltage regulator. A bad battery wouldn't stress an alternator, it would take 14 volts and not charge.......no stress on the alternator.

 

 

You bring up a good point, maybe unintentionally.  No offense.  He has one of these - http://www.datsunstore.com/high-output-alternator-p-1.html

 

Which are wired as "one wire" alternators, apparently, by the description.  Maybe he left something plugged in that shouldn't be and it's messing things up.

 

"These are internally regulated units and bolt right onto your z or other Datsun just like a stock alternator. For the externally regulated vehicles, all you have to do is unplug your voltage regulator and tape off the connection. All stock Datsuns use an external regulator up through 1977. You don't have to use the T plug in that goes in the back of the stock alternator either, just tape it off and lay it over to the side."

 

 

I wasn't saying the alternator is over-stressed, just that it was at maximum output,   Which means maximum torque required on the belt.   Which is why Oliver specified a special deep V (high contact) belt.  Because the stock belts slip.

Edited April 27, 201510 yr by Zed Head

I got rid of the external voltage regulator after one failed on my 260 and the battery blew eating through the wheel well.  This is a ZSpecialties 125 amp alternator with internal voltage regulator, i got it about 7 years ago and have put about 5K miles on it.

 

Not sure if it's related because it had rained and the connections may have been wet but my headlights were flickering, I have Dave Irwin's headlight harness that runs off the battery.

 

http://www.datsunstore.com/high-output-alternator-p-1.html

 

The 7 years and 5K miles put a new spin on things though.  Same car?  What changed from when it worked and now, when it doesn't?  

 

Love a good puzzle.

Is your voltage regulator connection still properly sealed?

The 7 years and 5K miles put a new spin on things though.  Same car?  What changed from when it worked and now, when it doesn't?  

 

Love a good puzzle.

Swapped from an N42 to a F54 block, just had about 200 miles or so on the swap.  I'm wondering if a weak belt that is not aligned could have caused it to burn up?  The pulley for the alternator is ever so slightly offset towards the rear of the car from the water pump.

 

I'll have to check the connection to see if it is sealed, maybe water splashed on it from the rain we got yesterday while I was driving it?

Edited April 27, 201510 yr by gogriz91

My 95 suburban was stalling out on us recently. We have had a small short in it for years. The electrical shop couldn't find it so we put a circuit breaker in that fuse spot. The circuit breaker would trip and then reset when it cooled. They told me when it got to where it tripped more it would be easier to find. Recently it was tripping a lot and right before it would trip you would here the idle drop and sometimes the truck would stall. Turns out the brake light switch was shorting to the brake pedal when you stepped on it. Long story of all this is when the alternator loaded up on the direct short it would stall my v-8 Chevy that probably puts out north of 350hp and 400 Ft lbs of torque. Your belt may have been weak and it may be misaligned but I wouldn't rule out something loading the alternator up, especially since your headlights were acting up too. When they try to feed a dead short they get really hard to turn...

 

On the headlight bypass are the feeds to the lights fused? I have these from Dave but I haven't installed one yet. If the feeds aren't fused and you developed a short there the alternator would probably shred the belt...

That's a good example of the load problem.  I was probably off on the bad battery as the cause since the current has to go somewhere.  The fact that the battery showed as fully charged would mean that current output dropped (assuming that's what the tester measures).

 

Could be that the bad regulator boiled the battery, leading to the test results.  That happened to me with a 74 Dart Sport.  The battery survived but the ignition module didn't.

 

I don't really like the "one wire" setups.  I assume that your ammeter doesn't work?  Since it's unconnected.  No indication of problems until it's too late.

Ammeter shows slight positive, I will check the fuse on the headlight harness, ordered new alternator from Z Specialties.

Talked to  Oliver at ZSpecialties, pulled the alternator, am sending it to him and ordering a replacement plus a Napa alternator and an external voltage regulator from MSA, one of these options has to work.

 

Thanks for all your help and recommendations