An unusual AC DELCO fault

Victor Smith (Harvest Gold 1089) had several old alternators serviced recently and was puzzled why a fault appeared when one of the alternators was installed on another V8. The cause is worth noting in case you are faced with similar symptoms. (Jan 04)

An interesting fault was discovered on a recently refurbished AC DELCO alternator the other day which was quite a puzzle. I took the unit back to Burghfield Starter Motor & Alternator Centre just south west of Reading who had refurbished it and Kevin Hall ran the unit up on his test rig keen to find out why the unit was not functioning correctly. Under test the ignition light came on and then slowly went out, but checking the small plastic covered connector on the top terminal was fully pressed home brought an intermittent fault. So the unit was opened up and the diode checked.

The top spade connector is at one end of the diode unit and pops through the case of the alternator. It has small spot welds to an extension to the terminal going inside the body of the diode unit. On very close inspection, and I mean a very close inspection, it was just possible to see there was some movement suggesting a faulty spot weld and connection to the terminal.

Now the diode unit had been replaced when the alternator was refurbished less than three months ago and the alternator had been in store until fitted to another MGBGTV8 just before Christmas. The diode fitted as part of the refurbishment was a brand new replacement but as soon as another was fitted and the alternator run up again on the test rig, it performed perfectly. It is one of those experiences to tuck away in case you should meet similar symptoms with the AC DELCO alternator on your V8 one day.

AC DELCO alternator - you can see the top terminal which is connector to a terminal strip which goes into the body of the diode unit. A faulty spot weld was the cause of the intermitent fault. (Photo: Victor Smith)

Burghfield Starter Motor & Alternator Centre
Unit 2 - The Forge
Reading Road
Burghfield Common
Tel: 0118 983 2284

Dave and Kevin Hall run this operation providing professional rebuilds of starter motors and alternators including the AC DELCO fitted to the MGBGTV8.

Copyright reserved by the V8 Register