Lights (voltage?) flicker at idle.

[euromobile900]

Are you getting the flicker when the engine is reved up at all?

No flicker when the engine is revved. It more or less goes away.

[euromobile900]

Here's the latest in the saga:
I cleaned my battery posts and reamed out the terminals, discovering in the process that one clamp was nearly corroded through. After replacement, no difference, but I did start to notice the flicker manifesting itself in other ways as well. The fuel gauge goes up and down, no matter what speed I run the engine.

Also, I believe the flicker is not voltage, but amperage, because after running a good test with a voltmeter, it is more-or-less constant. Time to start testing grounds and alternator output, I guess!

[peva]

If you don't have sufficient current (amperage) the voltage will drop and will show on your meter if it is accurate enough. Sometimes small variations will not show on digital meter but only on an analogue one with a needle. Are you sure your battery's OK. Apart from that I would check the alt. and all connections.

[euromobile900]

Huh. I think I can find an analog volt meter in the cellar somewhere...
The gas gauge is just a voltmeter, yes? Maybe that is why it's fluctuating. In any case, I'm getting more symptoms, so maybe it will hurry up and catastrophically fail soon, revealing the problem without making me do diagnostics.

The battery always cranks the engine right over, sprightly as can be! It lasted all winter, starting at 5-10ºF multiple times.

[euromobile900]

New developments:
I attached an analog meter and found nothing amiss. Voltage steady! I think the fuel gauge must be having its own issues, since it only does it below 1/2 tank. So I attached a new, better (4 gauge) grounding strap to the alternator, and replaced the old (urethane) alternator bushings with good ScanTech rubber ones. I also checked and re-did the alternator field wire as well as the positive wire from the alternator. I gave the alternator shaft a quick wiggle and spin to check the bearings, and they're fine too. So far, so good...

Buttoned her up, and same problem with flicker, but my volt gauge reads a good 0.3V higher than it used to
Maybe next I will get the battery and alternator load-tested.

[peva]

I had occasion to reroute some of my cables recently. Made sure all the battery, starter and alternator connections were nice, clean and tight. Voltage when from 13 volts to 13.6 volts. It's amazing what you can lose through a less than perfect connection.

[euromobile900]

Latest installment in the saga:Alt bearings squeak when it's wet outside. Also, after prolonged periods of wetness, the volt gauge stays at battery voltage for about 10 excruciating seconds upon starting the vehicle. It's strange, the alternator doesn't squeak when it's not making power (it does turn) for those 10 seconds. Once volts go up, I get belt squeal for a bit, then alternator bearing squeak. Also, the flicker is happening at higher RPMs now. The frequency of the flicker changes depending on RPM, too. It's fairly strange.I'm beginning to think I need a new alternator.

[geoff weeks]

1st guess is bad connections, but you have not located one yet. Another possiblity is one or more open diodes in the alternator which will reduce the output and also make it more "pulsed" as all three phases are not being utilized. A proper chargeing system test should show if the diode are good. The longer time on start-up points also to diodes, but we are all guessing without a proper test.

[euromobile900]

Well, when the thing goes bad, I'll be changing my alternator. I have a spare one riding around with me in the trunk! I haven't found anybody who can do an in-car alternator test, and if I'm taking the thing out, I might as well replace it with one I know works. For now, I'm just living with it, which is fine by me, because I'm confident in my ability to change an alternator on the side of the road!

[jskrebs]

Wonder if the slip ring brushes are just barley touching. Can you pull the regulator and have a quick look? Also how does the alternator ground wire look? I got my alternator rebuilt with new bearings, slip ring and regulator/brush assembly for like $50 at a local shop.