Alternate Alternators?

[OkieGringo]

How do I tell if my alternator is a 70 amp or a 100 amp? Is there any way of telling by looking at it? If I just order a 100 amp, will it fit? I had it tested on the truck today and it's putting out just over 12 volts. It has an external regulator and the electric shop owner said that the regulator isn't the problem. I could have him rebuild it, but I think I'll go with a Autozone lifetime waranty and since even Timbuctoo, Idaho has a Autozone it would easy to get it replaced for free. OkieG

[tim94f250]

Okie,
Where is the vreg. located and is it an internal or external fan? I know on Delco alternators, the model# and amperage is stamped into the case. I can't tell by looking at mine. I do see some numbers on the backside of the alt. though. Tim

[Mr_Roboto]

The amp number will be stamped on the alternator, on the end where the long bolt goes through.

I know the newer (3G) alternators have a differnt case size between the 95 and 130 amp. I don't know if the same holds true for the older (2G) alternators. The best bet is to see of they have one in stock and match it up against yours for dimensions and wire connectors.

Has your alternator been checked by full fielding it yet? Full fielding takes the alternator to its full output, and eliminates the regulator and wiring. You would see about 16 volts at full field if the alternator is good.

If you have a "Motor's" repair manual, it will give instructions on full field testing. I'm afraid I don't know the exact procedure for the older alternators.

[speedracer815]

A couple years ago I replaced the 2G alternator in a car with 130amp 3G with built in regulator. It was pretty much a slam dunk other than upgrading wiring to the battery to handle the extra current and a little clearance grinding on the bracket. I think that's the route I'd go.

BTW, got it at Autozone.

[OkieGringo]

Thanks guys. The weather has turned good here, so I'll pull the worn out soft top off the Jeep, get the carb cleaned out and drive the Jeep around to get the alternator for the truck. Wish me luck, it's kinda hard not to get speeding tickets driving a 400hp CJ-5 around town [img]/ubbthreads/images/graemlins/biggrin.gif[/img]. OkieG

[datkinsonsr]

Place a jumper across the Field and Armature terminals to bypass the voltage regulator. If the voltage regulator is on the fender, you can disconnect the connector and jump the A and F terminals in the connector. This will send full voltage to the alternator field and voltage output should be about 16 to 18 volts.