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Hope all is well with everyone here.
So I just ordered a new alternator to replace a potentially failing alternator in my 89' that my sons drives everyday.
The one being replaced pulses the headlights and dash lights at idle and while running at higher RPMs, but it is less noticeable then.
The voltage regulator has been rebuilt and has plenty of meat there, so I don't think that is the issue.
From what I can see of the copper sleeve on the shaft, it looks to be hardly worn in as it was the original out of my 90.
The alternator is putting out 14.5, and the battery is accepting 14.5 as well.
The only thing that I did notice when taking it out of my 90' and swapping nuts off of the back is that the exciter stud is loose. I thought by tightening it down when I reinstalled it that this problem would go away, but alas it has not, so my suspicion is something in the wiring in the back of the alternator.
Any thought on this gremlin before I have to ship it back as my core?
Thanks in advance,
Matt
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Little red wire shorting to ground, bad alternator ground?
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Nope.
this alternator behaved this way in my 1990 car, just like it does in this car.
Different red wire, and ground.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Hi Dave,
Maybe there is a diode out, in the exciter circuit side and is faulting the regulator control.
A tear down is a good idea!
A main diode going weak that would cause a flicker.
A totally failed main diode or winding would be a low output voltage and current.
A good Mystery!
I’m not from Minnesota, but eh! Or A? (-:)
Phil
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I've had the same thing as Peter: two regulators, look similar; In two different alternators: one works; the other pulses, flickers, and requires high-RPM to work smoothly.
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240 drivers / parts cars - JH, Ohio
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Not the regulator.
Original regulator and newly rebuilt regulator make no difference, alternator still pulses.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Hi,
My daughter out west reported flickering lights on her 89 240. I mailed her a new regulator that she had installed and it cured the flickering.
I asked her to keep the old one and send me a picture, and I was surprized to see that the brushes were long, even, and had little wear. Because short brushes have always been evident in similar situations, I'm wondering if the fault might be elsewhere in the regulator.
If you have one, it might be well to try another regulator before condemning the alternator.
Peter
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This regulator was used in the alternator that I just pulled out and there was no pulsing in this one.
Really believe it to be something in the alternator itself. I need to tear it apart to find the root cause.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Hi Matt,
I agree again with Peter’s posts. If he is into maple syrup, he has got it thick and heavy today! (-:)
I Like grade B maple syrup!
I’m curious about the 14.5 voltage as it appears a bit high. 14.2 is about the tops but it could be all in variations between meters too.
Is that a reading right after starting the car?
I ask, as it should dial it back soon there after and run between 13.2 and 13.6 as a normal range over time.
The regulator also reacts to its outside temperature to control the voltage, if you study the charts.
The regulator might be the issue and It’s possible, if the brushes on a regulator ever got too short, before the rebuild.
The arcing of the brushes can cause that, if left long term. If that scenario happened it could weaken the electronics inside to respond abnormally.
It’s like you said a bad ground or cables in general can skew the reading of the true battery voltage or actually it’s the systems voltage.
The battery it’s self can play games, especially, if the battery has run down and then accepts going back up to completey charged state, really really quickly!
Keep up the vigil!
Phil
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Phil,
According to the FAQ: "Look for voltage between 13.8 and 14.6", so I believe my voltage is right where it needs to be.
I'll keep this alternator and send another one back as the core as it is now suspect more than this one.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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