C3: Did I fry my 69's alternator/voltage reg?

[Dan Pepper]

After doing some tune-up work on my '69 L46 Coupe, the ameter started to act funny: it jerks to the left off of zero (or slightly above) when any input, like brake lights are applied, then settles indicating a very slight discharge, or just off of zero charge when the brakes or accessory remains on. It also pulses in unison with turn signals - very abruptly to about -25amps, then back just under zero.

The ameter reads just over the center/zero mark when the car is running or at idle with no lights or accessories are on. And the ameter shows the alternator is charging to the + side after initial engine cranking/starting.

When doing the tune-up, I hooked a dwell meter up to the alternator's + and neg sides. Could this damage the alternator's internal voltage regulator? Could this have caused the "jerky" erratic action of the ameter gauge? The gauge does the same thing when the key is off and the brakelight is actuated.

[Wayne W.]

Re: C3: Did I fry my 69's alternator/voltage reg?

Sounds pretty normal to me, assuming that it charges with some RPM.

[Dan Pepper]

Re: C3: Did I fry my 69's alternator/voltage reg?

I understand that it is norman to see some ameter gauge movement when introducing a draw on the system, but the needle literally jumps in exagerated movements. Also, the gauge reads a slight discharge when running and the headlights are on, and even more of a discharge when the heater blower is running, and then an exagerated swing when the blinker is activated. I'm afraid that if I need to drive an extended period with the headlights on, I'll kill the battery.

The alternator is charging as as the ameter does show a positive current recharging the battery after initial starting/cranking (to about 35 on the gauge). Just seems like the alternator's ability to discern how much and when to charge has changed or been compromised after I was rattling around under the hood.

[Terry F.]

Re: C3: Did I fry my 69's alternator/voltage reg?

I don't think that is right. You could pull the alternator and have it tested at a parts store. I believe 69 has the built in regualtor. Terry

[Joe L.]

Re: C3: Did I fry my 69's alternator/voltage reg?

Dan-----

There may be some problem with your alternator. However, if there is, I doubt very much that it had anything to do with your incorrect hook-up of the dwell meter. It might just be something that been "coming on".

In any event, the alternator is quite easy to check out yourself with a VOM. Refer to the tests for the various internal components which are well detailed and described in your copy of the 1969 Chevrolet Overhaul Manual. While you have to disassemble the alternator for these tests, this is quite easy to do and is described. Each of the electrical components, including the regulator, can be checked for "good" or "bad". If they're "good", they're good to re-use; if they're "bad", you need to replace. It's as simple as that.

Most of the internal components of your alternator are GM and Delco-discontinued, including the regulator. However, they are all easily available aftermarket. The regulator, for instance, is Standard Motor Products VR-111 or NAPA/Echlin VR-148. It sells for about 25 bucks.

If you decide to give your alternator a general rebuild, which is not a bad idea if it's been in service for a long time, it's a very easy thing to do, too. However, there is one caution here if the alternator is an ORIGINAL 1969 unit. This involves replacement of the main drive and split ring end bearings. The 1969 case halves are very rare and very valuable and very hard to come by. The drive end case is VERY fragile and easily broken. So, the case MUST be properly supported and EXTREME CARE exercised when removing and replacing the bearings, ESPECIALLY the drive end bearing.

[Bill S.]

Re: C3: Did I fry my 69's alternator/voltage reg?

sounds like you loosened the ground at the alt. check there. if you do not have a volt meter what i always did was unhook the poss battery while it was running to see if it was charging. i am sure this is not accepted practice and i am sure some one will frown upon it. i have never hurt a car or alt to my knowledge doing this. my 70 LT1 which was a daily driver for many years had had this done through the years and i had never had to replace the alt but did find a bad battery a few times. check out the batt and posts as well. again i am only saying WHAT I HAVE DONE i am not saying it is right.