Alternator and wiring question
Senior User
Joined: Feb 2001
Posts: 119
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From: Dryden Canada
Alternator and wiring question
First question - is there any real difference in an alternator from an 85 5.0L V8 and an 84 4.9L I6? My parts truck has an 8 and I think my alternator is shot.
Second question - on the 4.9L (1984, 1bbl carb) there is a wire that runs from the valve cover to the body. A ground of some sort far as I can tell. Without it, the starter won't turn over. But here's the problem - when the engine doesn't fire right over, and I need to crank it a bit (like if it floods or something) that wire gets so hot that it starts to melt ... like smoking burning melting the plastic coating off the cable. Is it hooked up in the wrong place or could it just be from previous damage to the wire? It's only an issue when actually cranking the starter, otherwise it runs perfectly cool and problem-free. (The wire in question that is!) Is there a serious wiring issue here I need to address, and if so, what is the solution? I can usually figure these things out, but so far this one has me absolutely stumped!
Chris.
Second question - on the 4.9L (1984, 1bbl carb) there is a wire that runs from the valve cover to the body. A ground of some sort far as I can tell. Without it, the starter won't turn over. But here's the problem - when the engine doesn't fire right over, and I need to crank it a bit (like if it floods or something) that wire gets so hot that it starts to melt ... like smoking burning melting the plastic coating off the cable. Is it hooked up in the wrong place or could it just be from previous damage to the wire? It's only an issue when actually cranking the starter, otherwise it runs perfectly cool and problem-free. (The wire in question that is!) Is there a serious wiring issue here I need to address, and if so, what is the solution? I can usually figure these things out, but so far this one has me absolutely stumped!
Chris.
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Joined: Jun 1999
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From: Comox Valley, Canada
Alternator and wiring question
Ok about the wiring. You have a big ground problem. For some reason ther starter is grounding thru the bonding wire that goes from the valve cover to the firewall, not good.
Remove the wire that runs from the battery negative to the engine block. Clean up the negative battery post and the place where the wire connects to the engine block. Then throw the old negative wire as far as you can and get a new one
Also a good time to check the battery positive wire. Maybe even remove the starter and clean the mounting area for it also.
But at least clean and replace, if neccessary, the battery negative wire.
As for the alternators they should interchange, mounting brackets may be different. They just may not be the same amp rating.
Sparky
Remove the wire that runs from the battery negative to the engine block. Clean up the negative battery post and the place where the wire connects to the engine block. Then throw the old negative wire as far as you can and get a new one
Also a good time to check the battery positive wire. Maybe even remove the starter and clean the mounting area for it also.
But at least clean and replace, if neccessary, the battery negative wire.
As for the alternators they should interchange, mounting brackets may be different. They just may not be the same amp rating.
Sparky
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Alternator and wiring question
And if those instructions don't clear up the problem,consider that the starter has internal problems.
Maybe get it checked, if you take it out.
[b][i][font color=red]Dennis[/font][i][b]
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Maybe get it checked, if you take it out.
[b][i][font color=red]Dennis[/font][i][b]
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Please Don't Ask Me Any Tough Questions,
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Senior User
Joined: Feb 2001
Posts: 119
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From: Dryden Canada
Alternator and wiring question
Thanks for the info Sparky. I figured there was a grounding problem somewhere in the system. It was boggling my mind what would make that bloody wire melt like that. But nothing is coming as too much of a surprise to me at the moment, I expect silly crazy things to happen after getting a truck running that A) was in an accident and B) had been sitting for about 10 months. I'd already decided that I needed to do a little re-wiring, but now I have some good leads to start with. Thanks again, I'll let you know how it turns out! Worst case, I'll shoot the truck. 
:-X11
:-X11
