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mikev
10-05-2007, 11:36 AM
Ok guys this is on a 1988 4.3 V6 when i start it up voltage is right around 12 idling rev it up and it jumps to 14 and stays there for a minute or two then starts creaping up to 15 - 16 volts sometimes it will drop back down to 14 or so when idling again sometimes it wont. thought it was the gauge at first but when it does it my depth finder gives me an error High voltage. So I figure it is a bad voltage regulator unless you guys have any other ideas. also is the voltage regulator in the alternator requiring a rebuild.

gcarter
10-05-2007, 11:57 AM
Yep...rebuild. Or, there's a number of folks on eBay that sell new 60-70 AMP single wire alternators for about $70.00, just look under mercruiser. They're easier to hook up, and they are new, hard to beat the price too.

MOP
10-05-2007, 12:03 PM
One of the diodes in the diode bridge is crapping, don't run it until you either get it rebuilt or get another one. The over voltage will cost you!!!!!!!!

Phil

mikev
10-05-2007, 10:16 PM
Does anyone know where to get a rebuild kit for one last time I did one years ago it was like 12 bucks for the kit and took about an hour.

MOP
10-06-2007, 07:25 AM
I just Googled "alternator rebuild kits" and got a page full, maybe a supplier is close to you.

Phil

BigGrizzly
10-06-2007, 11:03 AM
Mike, be careful, this sounds more like a battery issue. When voltage spikes it is because the batter is low or had an intermittent short. My son just ran into this in his Jeep. Today it would start and tomorrow it wouldn't. At this point I told him to do the battery first because it was old anyway Strangely enough everything fixed itself.

mikev
10-06-2007, 12:47 PM
battery is fairly new I am going to pull alternator and have them test it at parts store then i can also get a rebuild kit for it if necessary.

mikev
04-24-2008, 02:18 PM
Hey guys finaly getting around to fixing this now the weather has warmed up and im dewinterizing. I was looking at the alternator trying to see it was a 1 wire setup or 3 wire so I could order a replacment and to my suprise the purple wire that runs into the alternator (its a 3 wire by the way) was loose and came right out of the alternator. I am thinking I found my problem with the voltage spiking atleast on the gauge not sure if it really was now I found this short. what do you guys think would that cause the symptoms im seeing or do I probably still need a new alternator?

BlownCrewCab
04-24-2008, 02:29 PM
The purple is the main 12v, but that still doesn't explain the 16v. some alternators when you start the motor they stay at 12v until you make enough rpm to "exite" and turn it on. (thats usually on the 1 wire alts) one common symptom of a bad diode is a dead battery, depending on which diode it is. The auto parts check up should be able to tell.

mrfixxall
04-24-2008, 04:43 PM
Hey guys finaly getting around to fixing this now the weather has warmed up and im dewinterizing. I was looking at the alternator trying to see it was a 1 wire setup or 3 wire so I could order a replacment and to my suprise the purple wire that runs into the alternator (its a 3 wire by the way) was loose and came right out of the alternator. I am thinking I found my problem with the voltage spiking atleast on the gauge not sure if it really was now I found this short. what do you guys think would that cause the symptoms im seeing or do I probably still need a new alternator?

Did the whole lead come out of the alternator or just the wire came off ? if the wire was loose it would melt everything it was connected to, also if the alternator was going bad they throw a/c voltage which could explane the voltage spike.

mikev
04-25-2008, 10:02 AM
Did the whole lead come out of the alternator or just the wire came off ? if the wire was loose it would melt everything it was connected to, also if the alternator was going bad they throw a/c voltage which could explane the voltage spike.
the whole lead pulled out of the alternator from inside the plastic sleeve where it goes in. When I was fishing around back there it came out. I bet it was loose inside that sleeve causeing the sporadic issue. I need to try and hook pop that cover off and solder it back on hopefully that will fix it. going camping this weekend so be next week before i get to fix it and test. I am praying thats all it was save me the 80 bucks for a new alternator so i can buy a little bit of gas anyway.