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alternator light flickering

Discussion in 'Workshop Forum' started by jvandyke, Sep 19, 2013.

  1. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    Sometimes my charge light flickers on and off when I'm cruising at speed. It's a GM CS130 alt. Belt feels appropriately tight to me. It's a bit inconsistent and I only notice it at night with quite a bit loading the system but turning systems off doesn't bother it. The voltmeter is indicating decent voltage the whole time. Weird.
     
  2. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Location:
    Philadelphia, PA
    LED or incandescent bulb?

    (I went back to incandescent for that one bulb in the inst cluster.)
     
  3. If it is NOT the bulb Jeff...

    Even GM alternators can have some problems.

    Could be a simple thing like a sticky brush or a marginal diode. If you have one with a warranty I would yank it out and retest and replace at the point of purchase.

    BUT... do not neglect checking all the wiring & connectors first! At teh starter as well!
     
  4. m5art

    m5art True Classic

    I would

    suspect brushes.
    Have had similar problem in my wife's BMW E30. Replacing regulator module (the brushes are integral to it) solved the problem one time. The other instance I had to replace entire alternator.

    Perhaps the best bet is to remove it from the car and take to the shop for testing. They usually do it for free (Parts Source in Canada, for sure others in US as well).
     
  5. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    old incandescent bulb for warning light
    good advice, I will suspect the alt. I went GM for cheap replacement and maybe that will pay off. I have been running a splash guard under it but I'm sure it's getting uber hot in there, I should put the air tube back on, (no rear cover to connect to and pull in air of course but couldn't hurt).
    I took that hose off this spring as I was convinced it didn't do anything, oops, could have lead to early demise.
     
  6. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Location:
    Philadelphia, PA
    I was thinking that since LEDs need so little electricity to illuminate, an LED bulb might flicker on a minute current flow that would not even be noticed by the filament on an incandescent.

    Just an idea, no science to back it up:fart:
     
  7. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    If I understand this light correctly (fat chance) any time the balance of roughly 13v is upset, it lights, so either the alt is dropping out or ramping up? But the volt meter just sits in the middle, well, slightly below middle, thing is at idle something is drops to darn near 10 but the light doesn't come on, it just flickers at steady cruise while the meter sits in the middle.
     
  8. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Location:
    Philadelphia, PA
    Idles at 10v and flickers while cruising....unless your connections got loose or corroded or something, time to yank it and take it back to the store for testing and probably replacement.
     
  9. m5art

    m5art True Classic

    analogue voltmeter

    has quite a bit of inertia and will not show higher frequency voltage dips, that you are observing as bulb flickering.
     
  10. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    So my voltage maybe quite erratic and the meter won't show it but the light will? I can buy that. I think it was a tad worse this morning. Better address before it quits making juice and I'm screwed.
    Reading the tech manual for the CS-130 and it talks about temperature:
    "The charge indicator works in much the same way as on other charging systems-the indicator lights when the switch is closed, and then goes out when the engine is running. If the charge indicator is on with the engine running a charging system defect is indicated. For all kinds of defects, the indicator will glow at full brilliance. A new feature of this regulator is that it will cause the charge indicator to be on with the
    engine running if the system voltage is too high or too low. The regulator is temperature-compensated; that is, it's voltage setting varies with temperature."

    Better put the cooling duct back on! It also states it pulls air through the back (maybe they all do, I assumed they blew it back from the front) anyway, then for sure the cooling duct can be helpful, I used to have the end of the duct just sitting hear the back of the alt, not thinking it did anything but maybe it really was providing cool air to the thing after all. Interesting.

    I sure don't have "full brilliance" of the indicator light yet though, just a flicker with occasional brighter longer on, then periods of no light at all.
     
  11. JimD

    JimD Waiting for Godot... Moderator

    Location:
    Missouri, USA
  12. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    air flow

    not sure how much good that would do on my GM alternator but could maybe mod it to fit somehow, or "nearly" fit, which is better than just pointing the open end of the duct in the general vicinity of the alt, now here's a thought:
    I believe air flow through the engine bay is up from below, out through the top, so pointing my air duct down at the alt is bad, routing to below would be best as the cool air would dump into it as it draws the air up and through.
    The other day I forgot to latch my engine lid (as I've done before), at anything above 40ish it starts to rise, at highway speed, it's straight up, great cooling, silly looking, no rear view, bit embarrassing, like leaving your fly open maybe. Does illustrate how powerful the air movement is though, enough to raise the pretty hefty lid like it's paper.
     
  13. JimD

    JimD Waiting for Godot... Moderator

    Location:
    Missouri, USA
    Been there done that

    more than once too. It is a little weird when you suddenly sense the rear window has gone dark for some reason. :)
     
  14. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    yah, it amazes me how much air must be pouring through there to lift that lid, hard to believe it has cooling issues with all that air (at speed), shouldn't need a water cooling system at all........not.
     
  15. budgetzagato

    budgetzagato Administrator Moderator

    Location:
    Olympia, WA USA
    It's also helped by the negative pressure that develops at the trailing edge of the roof/targa bar. It's also sucking the lid up is my point.
     
  16. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    yes, good point, draft from below or (more likely) a vacuum above=air flow, be cool to see an airflow simulation of the x, with and with targa in place and such, maybe that's the genesis of the snorkel, hard for the carbs to pull air in that is rushing up and out?
     
  17. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    It caught up with me! I got about 1 mile from home light flicker and meter dropped to zero. Then it came back up, then dropped back down. Aborted commute and reverted to minivan, (ouch).
    Will tear into it.
     
  18. jvandyke

    jvandyke True Classic

    Location:
    West Michigan
    belt was loose after all, cracking and obviously stretching as I had just tightened it, replaced, reshimmed alt for a tad better alignment (it appeared that the pulleys weren't quite aligned so I added another washer)
    meter is now running higher overall, no flicker, doesn't drop as much at idle either (could it be it runs better too? sure seems to, maybe the low erratic voltage was piss'n off the ECU).
    Anyway, will watch that belt for signs of fatique.
    CS130 alt seems fine, will put the cooling duct back on too when I have a chance.
    I just eyeballed from above and didn't like what I saw, looks mis-aligned still. From below, crank pulley to alt, straight edge held up there it looked good, from above, not so good, might have to tear into it and try again.
    I'm pretty sure running the belt slightly cock eyed doesn't make it very happy.
     
    Last edited: Sep 23, 2013
  19. lookforjoe

    lookforjoe True Classic

    Location:
    New York
    misalignment will definitely impact belt longevity & function - it will be more likely to glaze & slip if it's off kilter....
     

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