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Hi guys! My name is Rob and I’m new to FTE. I recently bought a 1970 F250 Camper Special with the original 360 and I’m still trying to work my way through it. I heard the truck turning over and starting when I went to pick it up but once I get home and put a new battery in it, things got interesting. I found that someone cobbled together a wiring patch that is now melting and smoking as soon as the battery gets connected. I’ve already replaced the starter solenoid and traced it as best as I can. It seems to be leading into a bundle that lands on the back of the altenator? I put in a few pictures so you guys can see what I’m talking about. Can anyone tell me if I’m right if this is the altenator ground? Does anyone know where I can get just this harness? I’m trying to do this project as a daily and a slow rebuild and can’t afford the $700 LMC wants for an entire trucks worth of wiring. Any advice would be great!
The wiring doesn't look bad, I have seen much worse. You have pretty stock wiring. It appears that's the charge wire to the alternator and someone has replaced the fusible link with basic wire. Take some more pictures and I can help further. Its a easy fix. If it's your daily driver then I will suggest making it easier on yourself and do a 3g alternator upgrade. You will gain reliability and your lights won't flicker at idle.
Welcome to the forum. "ford390gashog" is totally right on about doing the 3G alternator upgrade!! You can buy them at most any junk yard for about $25 - $35. They are super easy to install, and the wiper blades don't slow to a crawl when you turn on the heater (or A/C) fan. Plus you'll be getting rid of the old style of voltage regulator, and a bunch of old wiring. Check how to install one on page 2 of:
The starter relay solenoid gets the ground path it needs through the bracket and hardware attaching it to the inner fender. This is important. Nixon was president the last time that was serviced! One of the starter/battery cables looks to be original, genuine 1970 vintage, stiff as roadkill squirrel. The posts and connecting hardware and everything are pretty corroded. It won't matter what size alternator is installed, it will be practically crippled by high resistance electrical connections. Every single connection throughout taken together adds up, it makes a tremendous difference in engine starting, battery charging and ignition current available to the spark plugs.
Everybody is probably familiar with battery post corrosion, but they are all important. Not trying to beat up on you personally or anything, it's just that picture is a perfect illustration of how difficult the automotive electrical environment is! It's amazing they work at all after 50 years. Recommend purchasing a complete set of heavy duty gauge cables, and clean the connections to bare shiny steel at block, frame, firewall, etc., and tighten securely. $10 says the engine will even warm up quicker, everything doesn't need to be all purty in there necessarily but it does pay to keep those electrons happy in the wires.
Wow! I don't that picture. I just saw the alternator and the heater hoses with a few wires in view. Rob, it be a very good idea to make a "complete link of grounds". By that I mean, get some heavy cable, run a 2nd wire from the battery to the frame (just below the battery). Run another wire from the frame, up to the alternator adjustment bolt (or somewhere in that area of the engine). Then run a wire from the passenger side inner fender over to the firewall (I used one of the studs by the heater, with a washer and locknut). Then do the same on the other inner fender. That way the frame, cab, and the fenders are all linked (and grounded) together. Some members have also installed an additional ground from the passenger side frame over to the starter mounting bolts. Additional GRD to frame- next to VIN on frame- Extra GRDs from inner fender to radiator support, then one to the voltage reg and other wire to headlight frame
The wiring doesn't look bad, I have seen much worse. You have pretty stock wiring. It appears that's the charge wire to the alternator and someone has replaced the fusible link with basic wire. Take some more pictures and I can help further. Its a easy fix. If it's your daily driver then I will suggest making it easier on yourself and do a 3g alternator upgrade. You will gain reliability and your lights won't flicker at idle.
I couldn't disagree more about the 3G alternator. Don't open a new can of worms, stay with the factory setup. My lights have never flickered at idle on any of my trucks. If they did it would mean that one phase of your alternator is shot.
Also, why not repair the defective grounds that the vehicle came with that have worked for 50 years? A voltage drop test will locate good and bad grounds if any. There is no need to re-engineer a system that has worked well, just fix what's there.
I exited and re-opened the program. Now I can see both pictures. I may have gone a little over board with all the extra grounds that I installed. But you'll see that most of the electrical problems brought up on this forum has a bad ground involved. I also ran an extra ground from the bolts (I prefer to use stainless steel nuts and bolts on things exposed to the weather) on the starter relay over to the firewall. I did that because my current inner fenders are pretty rusted up, and I didn't want any starter problems.
I also went with a larger size positive cable from the battery to the starter solinoid, and down to the starter. Notice the black GRD wire on the mounting bolt- on the inner fender.
Notice the GRD cable?? Notice the battery cable the size of garden hose! Better keep yer hood locked chief, the meth-head tweaker copper scrappers would salivate at the sight of all that.
I appreciate your electrical work but at some point friend the term "overkill" needs to be considered. The cables on a semi truck with dual 8d batteries wired for 24 volts aren't that big. Those cables are sized to handle 1000 amps or more. Don't you think that's a little excessive? The starter amperage draw on our old trucks probably never exceeded 150 amps at the most.
I don't see any thing wrong going "over kill" if you got the money for it.
What do they say? Go big or go home!
As part of my 81 F100 flare side (300 six) rebuild I replace all the battery cables and I also went bigger than what the truck had from the factory.
I even had to solider the frame tab on the cable like the factory had for the ground.
Tab bolted to frame like factory. It is the cable on the right, the left is an insulated cable holder for the POS to the starter.
My truck also has a ground wire (10 ga) from motor to firewall and a braided cable from firewall to hood, all factory.
When I get the bed mounted I will add a ground wire from frame to bed just for good measure.
Dave ----
Oh for the OP that wire is a fuse link made to blow if the draw is too high.
Now you cant use a normal fuse as it will blow when the load is added to it where the fuse link is a "time delay" fuse.
When you send power thru the link it starts higher than a fuse can handle then comes down to a normal level.
You can get new links at the local parts stores in the help area. Think they have a crimp butt connector on them already just use the right tool to make the crimp.
I would remove the tape from the wires to make sure all is good.
I would then get a new link and run it to the starter relay (where that other wire is) and to the wire it should go to from the ALT if that is where it goes.
Go over all the grounds and I would replace all the battery cables for piece of mind.
If the battery is good you should be good to go.
Dave ----
I appreciate your electrical work but at some point friend the term "overkill" needs to be considered. The cables on a semi truck with dual 8d batteries wired for 24 volts aren't that big. Those cables are sized to handle 1000 amps or more. Don't you think that's a little excessive? The starter amperage draw on our old trucks probably never exceeded 150 amps at the most.
That is only 1ga cable in that picture. The class 8 trucks use 2/0 cable which is much larger. That is comfortable at 200 amps max which is perfect for these trucks.
That is only 1ga cable in that picture. The class 8 trucks use 2/0 cable which is much larger. That is comfortable at 200 amps max which is perfect for these trucks.
Tough to tell from a pic, that looks like 00 is the smaller stuff. The garden hose size has to be larger than that. For those that don't know, in AWG the smaller the # the larger the diameter. 8,4,2,1... then 0, 00, 0000 is larger yet.
That is only 1ga cable in that picture. The class 8 trucks use 2/0 cable which is much larger. That is comfortable at 200 amps max which is perfect for these trucks.
Oh for the OP that wire is a fuse link made to blow if the draw is too high.
Now you cant use a normal fuse as it will blow when the load is added to it where the fuse link is a "time delay" fuse.
When you send power thru the link it starts higher than a fuse can handle then comes down to a normal level.
You can get new links at the local parts stores in the help area. Think they have a crimp butt connector on them already just use the right tool to make the crimp.
I would remove the tape from the wires to make sure all is good.
I would then get a new link and run it to the starter relay (where that other wire is) and to the wire it should go to from the ALT if that is where it goes.
Go over all the grounds and I would replace all the battery cables for piece of mind.
If the battery is good you should be good to go.
Dave ----
Fusible link wire is merely wire that is 4 gauges smaller than the circuit it protects. His excessive amperage draw is going to have to be located and repaired. Only then can he be expected to be "good to go".
