Alternator-- again

[Ed Hickey 32630]

Just wanted to let those interested, the problem with the 82 charging system came back. The good news is it now in their solid. The dash gauge shows battery voltage, 12VDC.

A voltmeter shows about 46 VDC on the alternator's battery terminal. The red wire is 12VDC and the brown wire is about 20VDC.

I put an oscilliscope on the output of the alternator and it there is no AC supperimposed that could be throwng the reading off.

The alternator tests good.

Ed

[Duke W.]

Re: Alternator-- again

At this point I'd recommend taking the alternator apart and running all the static electrical checks on the stator, rotor, diode trio, rectifier bridge, etc. The procedure is probably in the Chassis Overhaul Manual, and there are lots of GM manuals that contain the basic checks for the 10-SI Delcotron. Now that the failure is solid, something should show up. It's easy to disassemble the alternnator. You can take off the rear frame without removing the pulley nut and remove all the guts, but you'll have to remove the nut and pulley to change the rotor if it doesn't check out. Also, carefully inspect the nylon insulating washers. There are two on the the regulator mounting screws.

I'd also take a careful look at the terminals on the side harness and make sure they are still firmly attached to their respective wires. Also carefully inspect the regulator spades with a caliper to see if they are worn.

I don't know of any way to electrically check the regulator, though I think there are some test sets out there that can test them. For the price, I usually just install a new one and a set of brushes if they are more than about half worn. I use Borg-Warner parts from Pep Boys because there is one near me, but NAPA, Niehoff, and Echlin are the same. It's all Dana Corp. manufacturered.

A little hint to avoid a possible disaster and proof that I can be as klutzy as anyone else. The last time I overhauled the Cosworth Vega's 10-SI I put it back on the car without removing the paper clip that you use to retract the brushes when installing the rear frame. Fortunately I caught it before I started the engine. I don't know what would happen if you power up with the field leads shorted, but I'm glad I didn't find out.

Duke

[Ed Hickey 32630]

Re: Alternator-- again

Duke,

I can find nothing wrong with the alternator. But I found a schematic from ALLDATA. The BAT lead on the alternator goes directly to the battery. I connect a wire from the BAT terminal to the positive side of the battery and the car charges. The voltage on the BAT terminal goes to 14.5VDC.

I traced the wires from the BAT terminal and they go into the firewall. According to the schematic, it probably goes to the AC Hi-LO relay. Inside the plastic tubing that surrounds the wiring, I found a corroded splice. I cut the splice out and soldered the wires together. Same problem.

The wires to the starter have been spliced. I soldered them together. Same problem.

The interesting thing is there is about 20 ohms resistance from the wire on the alternator to the starter solonoid. It should be zero.

The air conditioner works ok, so I think the wire is bad between the HI-Lo relay and the alternator.

The ALLDATA schematic shows fusible links but there are no fusible links on the car. So the ALLDATA book may be wrong about the air conditioner relay too.

I am thinking of just running a 10 GA wire from the BAT terminal at the alternator to a 14GA fusible link, under the floor and up to the battery.

I talked to a few people and they think this is the easiest fix. This is not a show car, it is a nice driver.

Do you have any suggestions?

thanks for all of the help,

Ed

[Duke W.]

Re: Alternator-- again

I'm out of suggestions. I've never had a wiring problem other than maybe a connector. I don't know how accurate your wiring diagram is but the '82 Chassis Service Manual is probably the most accurate. As a general rule, connectors are the most probably suspect if there are wiring problems.

Duke