Can our alternators be rebuilt economically?

[sdweatherman]

Alright - I know there are some electrical experts on this forum. I think my alternator is starting to overcharge, so I am wondering if it can be rebuilt. Its the older round-back version. Does anyone sell a "kit" to rebuild these, or do you just need to buy the essential parts? And just what are the essential parts I would need?
Thanks,
Scott.

[71bird]

Have you tried calling a starter generator shop? Most can do it by just replacing what is bad, but I suggest Jim Ridge in S.C. he can make it look just like new with date coded parts. Also never let anybody blast the cases or he can't make them look new again.

[sdweatherman]

Thanks 71bird,
I am pretty handy and have the tools, so I am looking to do this myself. Just wanted to get some pointers from someone that has gone through one. Also looking for the best place to get the parts from. Thanks!

[moparite]

I think my alternator is starting to overcharge,

Your alternator is not a GM style that has a internal regulator. Your voltage regulator is at fault not the alternator.

[sdweatherman]

Thanks moparite,
That was my first thought, but a new regulator did not solve my problem. I guess its possible that I got a bad one. Any other thoughts on why my ammeter is fluctuating on the high side?
Scott.

[71bird]

Check the voltage at the wires going to the VR, and compare to battery voltage.If the bulkhead connector and the connectors inside the car have any resistance the VR will tell the Alt to put out more volts.

[sdweatherman]

Thanks! When I get a chance I will check them. Scott.

[road chicken]

The guys are right on. If the Amp-meter is going to the high side that usually means the alternator is working and the voltage regulator is suspect or there is a high current draw on the system back to the battery. Since the VR case to ground is a very common issue, unscrew one of the mounting screws, clean the firewall and VR case, and then put a star-washer between the FW and VR case and tighten it back down. a little electrical grease doesn't hurt either if you have it- keeps it from corroding over time. Double check for good clean connections as corrosion or loose ones are the typical issue.
If that doesn't work and you have a volt meter check the voltage between ground and the output side of the ALT, check the voltage at the Starter relay post, and the battery. These should be no more than 14.5 MAX. 13-13.5v is typical when running- no accessories and with high idle ( 1200 -1500 rpm). Also check the blue field wire at the alternator. That has the voltage the VR is seeing as a reference, (and the green is controlled by the VR to vary the ALT output). The reason is, if you have good voltage at the ALT output but it drops to 12.0 volts at the Starter Relay- you have a bad connection ( typically in the bulkhead connection). Don't get to wrapped up in this part yet, just check for good connections and the battery is good.
The battery standing voltage,( unhooked, fully charged, and allowed to rest for 1 hour), should be between 12.8v- 12.4v, out side of that the battery is getting weak, ( 90% of a batteries capacity is between 12.8 and 12.4V).
Our alternators can be rebuilt very cheap if the armature is in good condition,( That means the windings are not burnt up and the commutator bars, ( the copper bars the carbon brushes ride on) are good, ( no raised bars and not grooved up to badly) they are fairly easy to rebuild. The rebuild kit consists of the 6 Diodes, and the carbon brushes, sometimes the springs for the brushes. The are simple to replace but the commutator should be dressed smooth as well. The only other items that go bad are the bearings. The rear case bearing is relatively easy to do, but the front is going to require pulling the pulley and a press to do.

[sdweatherman]

Thanks road chicken, I will be investigating on Monday. Scott.