Rebuild your alternator for $8, Follow along while I replace the bearings in my alternator Options

[Van]

Also posed in 914club - I decided to replace the bearings in my alternator. Grand total = $8.00!

Follow along here: http://www.ephotomotion.com/914engine/alt1.htm

[Red76]

So after I finished replacing the bearings, brushes and checked the diodes I slapped it all back together and took it to my local Advance Auto store for them to run a test for me. Amazingly they had the right clip to plug it up with. Once they spun it up it came up with a diagnosis that it fails to show a charge. The guy asked me if the voltage regulator was internal or external. I told him its external and his reply was that makes this a generator then and we cant test generators.

Ok so I asked my buddy his opinion since he works on lots of old stuff. He said just lock it down in a vise on the benchtop and spin it with a cordless drill hook the test leads to your volt/ohm meter and see what voltage it reads.

Bada bing bada boom! It put out 30 plus volts.

[bbrock]

So after I finished replacing the bearings, brushes and checked the diodes I slapped it all back together and took it to my local Advance Auto store for them to run a test for me. Amazingly they had the right clip to plug it up with. Once they spun it up it came up with a diagnosis that it fails to show a charge. The guy asked me if the voltage regulator was internal or external. I told him its external and his reply was that makes this a generator then and we cant test generators.

Ok so I asked my buddy his opinion since he works on lots of old stuff. He said just lock it down in a vise on the benchtop and spin it with a cordless drill hook the test leads to your volt/ohm meter and see what voltage it reads.

Bada bing bada boom! It put out 30 plus volts.

@Red76 do you remember where you connected the test leads for this? I'm not sure where to check with the voltage regulator not connected.

Thnx

[Red76]

So after I finished replacing the bearings, brushes and checked the diodes I slapped it all back together and took it to my local Advance Auto store for them to run a test for me. Amazingly they had the right clip to plug it up with. Once they spun it up it came up with a diagnosis that it fails to show a charge. The guy asked me if the voltage regulator was internal or external. I told him its external and his reply was that makes this a generator then and we cant test generators.

Ok so I asked my buddy his opinion since he works on lots of old stuff. He said just lock it down in a vise on the benchtop and spin it with a cordless drill hook the test leads to your volt/ohm meter and see what voltage it reads.

Bada bing bada boom! It put out 30 plus volts.

@Red76 do you remember where you connected the test leads for this? I'm not sure where to check with the voltage regulator not connected.

Thnx

My alternator/generator is from a 76. Not sure if they changed any over the years. Probably not. There should be a plug-in on the back of the unit with 2 terminals. You can use an alligator clip t either one of them and the body of the unit is the ground wire. You can see the fins on the pulley are designed to draw cooling air into the unit while running so spin it in the direction that would pull air into your unit. If there is no current from the terminal you choose just switch to the other one and try again. Should be something there.

[bbrock]

So after I finished replacing the bearings, brushes and checked the diodes I slapped it all back together and took it to my local Advance Auto store for them to run a test for me. Amazingly they had the right clip to plug it up with. Once they spun it up it came up with a diagnosis that it fails to show a charge. The guy asked me if the voltage regulator was internal or external. I told him its external and his reply was that makes this a generator then and we cant test generators.

Ok so I asked my buddy his opinion since he works on lots of old stuff. He said just lock it down in a vise on the benchtop and spin it with a cordless drill hook the test leads to your volt/ohm meter and see what voltage it reads.

Bada bing bada boom! It put out 30 plus volts.

@Red76 do you remember where you connected the test leads for this? I'm not sure where to check with the voltage regulator not connected.

Thnx

My alternator/generator is from a 76. Not sure if they changed any over the years. Probably not. There should be a plug-in on the back of the unit with 2 terminals. You can use an alligator clip t either one of them and the body of the unit is the ground wire. You can see the fins on the pulley are designed to draw cooling air into the unit while running so spin it in the direction that would pull air into your unit. If there is no current from the terminal you choose just switch to the other one and try again. Should be something there.

Interesting, sounds like a different alternator model than mine. All the 914 alternators I've seen have 3-Terminal connectors on the back (D+, D-, and DF) and I've never seen one with cooling fins on the pulley. I did get voltage from one or two of those terminals but not much. My understanding is that the exciter circuit needs to be energized somehow to get the alternator to kick in to full output mode. I haven't found info on how to do that for bench testing though.

I had a similar experience with my FLAPS but only after being told over the phone that they COULD test an alternator with external regulator and making a one hour round trip to town to discover they could not. After rebuilding, all my individual components (rotor, stator, diodes) tested good so I just bolted it in and will test when the engine is connected.

Thanks for your help. (IMG:style_emoticons/default/beerchug.gif)