I had this happen when the sense wire on mine had an intermittant connection. 
Alternator bad?
Thread Starter
Racer
Joined: Jul 2013
Posts: 294
Likes: 10
From: Palmer Alaska
Alternator bad?
So I'm driving down the road and my guage jumps to 18V and stays there. I moment later drops to 14. Then goes back. I find a bumpy area and watch for change hoping for loose connection! Stays at 18. On the way home, smooth road goes back to 14. Alternator is 1 yr old, Delco unit, two wire plug on side with Bat term on back. Not sure if that was the stock setup on an 80 or not. So I hate intermittent elec issues so any suggestions on where to start, I have an idea but figured I would ask the group.
Belt is tight, not overly, connections to alternator are snug, all the engine and chassis grounds are solid as are batt connections. Batt cables are new.
Belt is tight, not overly, connections to alternator are snug, all the engine and chassis grounds are solid as are batt connections. Batt cables are new.
Last edited by akdale; May 20, 2014 at 12:02 PM.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
I also think you have a bad/weak connection somewhere in that 2-wire plug. One of the lines may have poor connection with the connector. Or, one of the wires could be fracturing thru INSIDE the insulation. Or, the connector may not be making good contact with the spade lugs...or the lugs could be corroded.
Lots of possibilities for bad connections. It would be unusual to have an intermittant voltage regulator module. Usually, it either works...or it doesn't.
Lots of possibilities for bad connections. It would be unusual to have an intermittant voltage regulator module. Usually, it either works...or it doesn't.
Race Director
Joined: Nov 2002
Posts: 12,142
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From: Taylor Michigan
Since you have not indicated what year you have, 68 is the only year with a remote regulator. Starting in 69 the regulator was built in the alternator......and the proper operational voltage is anywhere between 13.6 to 14.4.....the high voltage above 14.4 can damage electrical components and blow bulbs ect....heed your guages
Thread Starter
Racer
Joined: Jul 2013
Posts: 294
Likes: 10
From: Palmer Alaska
I replaced the two wire molex connector a while back and reteminated the wires. I will have someone move that around while the car is running to see result. I agree it does seem like loose connection or bad wire. Figured going over bumps would have caused the problem to arise if it was a loose connection.
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Thread Starter
Racer
Joined: Jul 2013
Posts: 294
Likes: 10
From: Palmer Alaska
While running I had a helper watch the gauge while I moved wires and plugs. Everything is tight and no amount of movement is causing the issue. Visual inspection shows no damaged wires. I am connecting a digital multi-meter and running it as my dc volt gauge and see what happens.
Thread Starter
Racer
Joined: Jul 2013
Posts: 294
Likes: 10
From: Palmer Alaska
I hesitated just because issue is intermittent. Took to schucks, test fine three times in a row.
I connected my timing light which measures voltage and while setting timing the issue occurred and registered 17.5 volts.
I'm going to just add ground straps from engine to frame rather than check what's there now. More straps can't hurt and it's easy to do.
I connected my timing light which measures voltage and while setting timing the issue occurred and registered 17.5 volts.
I'm going to just add ground straps from engine to frame rather than check what's there now. More straps can't hurt and it's easy to do.
Le Mans Master
Joined: May 1999
Posts: 6,692
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From: Texas
You will definitely burn things up running 18 volts. My alternator did that once and the a/c blower would really blow air. But, came close to burning it up before I got it replaced. Its not worth $100 to get another alternator if the connectors turn our ok.
Thread Starter
Racer
Joined: Jul 2013
Posts: 294
Likes: 10
From: Palmer Alaska
Meant to post final result. Took alternator in to get it tested. Passed their test 3 consecutive times. put back in car, went for drive, 17 volts. Took back, got new alternator, been fine since.