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| alternators again [message #149554] |
Sun, 13 November 2011 11:41  |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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It all started with an intermittent flash of the alternator light. Most recently, in a 1/2 hr drive, it might blink 4 or 5 times, quick blink on, then off again. Meanwhile my dash voltage gauge is pegged. Have yet to follow the wires to see exactly where it's connected (it's not OEM).
So I hooked up a DPM reading directly off the battery at the firewall junction post, ground at the ground of the isolator. Most of the time in the 1/2 hr 55mph drive, it is about 13.6v, sometimes 13.8; but at least once it went erratic, and bounced around from 14v to 16v. Is this just a loose connection or is this an intermittent failure mechanism going on? (Erratic meter didn't coincide with light flicker.)
Thanks for your help.
Jay Rabe
76 PB
Portland, OR
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| Re: [GMCnet] alternators again [message #149557 is a reply to message #149554] |
Sun, 13 November 2011 11:55  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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in my case, it was a short in the stator windings, ( a Napa rebuild) .
was very intermittent, until I finally got the alternator rebuilt by a
local shop , and he replaced the stator winding ( Napa normally does not do
this, and all of the stators have been toasted over the years.
good luck
gene
On Sun, Nov 13, 2011 at 9:41 AM, Jay Rabe <jayrabe@hotmail.com> wrote:
>
>
> It all started with an intermittent flash of the alternator light. Most
> recently, in a 1/2 hr drive, it might blink 4 or 5 times, quick blink on,
> then off again. Meanwhile my dash voltage gauge is pegged. Have yet to
> follow the wires to see exactly where it's connected (it's not OEM).
>
> So I hooked up a DPM reading directly off the battery at the firewall
> junction post, ground at the ground of the isolator. Most of the time in
> the 1/2 hr 55mph drive, it is about 13.6v, sometimes 13.8; but at least
> once it went erratic, and bounced around from 14v to 16v. Is this just a
> loose connection or is this an intermittent failure mechanism going on?
> (Erratic meter didn't coincide with light flicker.)
>
> Thanks for your help.
>
> Jay Rabe
> 76 PB
> Portland, OR
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] alternators again [message #149558 is a reply to message #149554] |
Sun, 13 November 2011 11:58 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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also
you did check the belt tension -- right---?
http://goo.gl/IVjzh
gene
On Sun, Nov 13, 2011 at 9:41 AM, Jay Rabe <jayrabe@hotmail.com> wrote:
>
>
> It all started with an intermittent flash of the alternator light. Most
> recently, in a 1/2 hr drive, it might blink 4 or 5 times, quick blink on,
> then off again. Meanwhile my dash voltage gauge is pegged. Have yet to
> follow the wires to see exactly where it's connected (it's not OEM).
>
> So I hooked up a DPM reading directly off the battery at the firewall
> junction post, ground at the ground of the isolator. Most of the time in
> the 1/2 hr 55mph drive, it is about 13.6v, sometimes 13.8; but at least
> once it went erratic, and bounced around from 14v to 16v. Is this just a
> loose connection or is this an intermittent failure mechanism going on?
> (Erratic meter didn't coincide with light flicker.)
>
> Thanks for your help.
>
> Jay Rabe
> 76 PB
> Portland, OR
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] alternators again [message #149564 is a reply to message #149554] |
Sun, 13 November 2011 12:27 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Jay, I had a similar problem on a coach at the SOOR rally in September. It
turned out to be the stud that your output lead attatches to. It was loose
on the inside of the alternator where the connection from the rectifier
connects to that stud. That stud has a large amount of amperage passing
through it, and it heats and cools. That eventually causes it to work
loose. Check by putting a wrench on the output lead holddown nut and move
it back and forth a little ways. if the whole stud moves, I would look
there first. Second place would be ground wires.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sun, Nov 13, 2011 at 9:41 AM, Jay Rabe <jayrabe@hotmail.com> wrote:
>
>
> It all started with an intermittent flash of the alternator light. Most
> recently, in a 1/2 hr drive, it might blink 4 or 5 times, quick blink on,
> then off again. Meanwhile my dash voltage gauge is pegged. Have yet to
> follow the wires to see exactly where it's connected (it's not OEM).
>
> So I hooked up a DPM reading directly off the battery at the firewall
> junction post, ground at the ground of the isolator. Most of the time in
> the 1/2 hr 55mph drive, it is about 13.6v, sometimes 13.8; but at least
> once it went erratic, and bounced around from 14v to 16v. Is this just a
> loose connection or is this an intermittent failure mechanism going on?
> (Erratic meter didn't coincide with light flicker.)
>
> Thanks for your help.
>
> Jay Rabe
> 76 PB
> Portland, OR
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Unsubscribe or Change List Options:
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| Re: [GMCnet] alternators again [message #150150 is a reply to message #149564] |
Sat, 19 November 2011 17:46 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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Senior Member |
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Thanks Jim, but the alternator stud appears to be tight. A little hard to be sure. And thanks to GeneF for that "Doh" moment. The alt light flicker may indeed have been nothing more than a loose belt. I finally installed the clever belt tightener thingie that I got from JimK. Works like a dream. If I can get the timing done today (separate thread...) I'll drive it again tomorrow and test out the belt tightening fix.
Thanks,
Jay Rabe
76 PB
Portland, OR
> Date: Sun, 13 Nov 2011 10:27:33 -0800
> From: jamesh1296@gmail.com
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] alternators again
>
> Jay, I had a similar problem on a coach at the SOOR rally in September. It
> turned out to be the stud that your output lead attatches to. It was loose
> on the inside of the alternator where the connection from the rectifier
> connects to that stud. That stud has a large amount of amperage passing
> through it, and it heats and cools. That eventually causes it to work
> loose. Check by putting a wrench on the output lead holddown nut and move
> it back and forth a little ways. if the whole stud moves, I would look
> there first. Second place would be ground wires.
> Jim Hupy
> Salem, OR
> 78 GMC Royale 403
>
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