Hi guys, I am new here and have posted a couple times about this problem with out much response. I have an issue that I really need help with, so if anyone has any suggestions what-so-ever, please reply.

I have a 78 f100, 300i6, 3 speed manual tranny. The clutch went out about 3 weeks ago. I needed to move it to level ground though, so I tried to start it. It did not turn over. There was a pop from under the hood, and the fusible link from alternator to solenoid went up in smoke. The power wire from positive post to solenoid was hot.

I took the stater off, had it tested. It did engage, but was making a really sick clunking noise, so I replaced it. I also bought a new solenoid. Put the starter on the truck, wouldnt start. Put the solenoid on the truck, and it turned over once, and then smoke came off the solenoid.

Replaced solenoid again. This time, no smoke, just clicking. So we hooked jumper cables up to it. The jumper cables went up in smoke when I turned the ignition key.

Took starter and battery in for testing. Both are fine. Bought a new ground wire (since it was 10 gauge instead of 2). Cleaned all connections at solenoid and the engine ground. Tried to turn it over, solenoid went up in smoke.

So i started unwrapping all the wires in the engine bay. No shorts found. got in the cab, and all the wiring through the dash was completely wrapped, no bare wires touching ground anywhere.

Bought new solenoid. Still just clicks.

Alright....possible causes....go!

 

Are you trying to start it while in gear? Maybe it's not your clutch, maybe the engine is siezed? Or maybe the throw out bearing is siezed. Or maybe your transmission is frozen up? I'm just throwing these things out there for you to check.

 

I changed the disc, pressure plate, throw out bearing. Transmission turned just fine, flywheel turned just fine. I have made sure that I am in neutral by pushing the truck (just installed aftermarket floor shifter).

I've eliminated all those possibilities

Thanks for the reply though .

 

Have you tried jumping the solenoid directly?

 

yes, all it does is throw off some monster sparks.

Since you brought that up, here is another thing I tried.

I hooked negative post up on battery, disconnected starter wire from solenoid, and put starter wire directly to positive post on battery. Threw sparks. Took starter off and had it tested, it tested just fine.

 

By the sounds of it you have a short somewhere in the system. You should not get "monster sparks" jumping the solenoid. If the solenoid and starter are good you should be able to jump the solenoid to get it to start.

I would look between the bellhousing and motor and see if you have a wire pinched between there.

 

There is only one wire in that area, and it appears to be a ground wire since it actually attaches to the top driver side bellhousing bolt.

From there back, there is one bundle of wires heading to the rear of the truck on the inside of the frame. Checked all of those wires, no shorts.

Checked all the wires in the engine bay, no shorts...I'm lost!

 

Some additional information:

Currently I have the alternator isolated from the ignition circuit in case it is a short, i dont want to have to replace it too!

 

Make double sure you haven't reversed the polarity at the battery, the altenator, or at the starter.

 

Thanks for the reply guys.

Keep in mind though that this problem occurred all of a sudden after never having this problem. I went to start it and POOF...the fusible link wire went up in smoke. Just happened to be right after the clutch went out. After checking all the wires in the engine bay and replacing Solenoid and Starter, the same issue is happening.

I know there is no neutral safety switch on this truck, but is there ANYTHING related to the clutch or tranny that would be causing this issue? Also, what about the rest of the parts that are unfused on the ignition circuit (coil, ignition module, voltage regulator)?

I am about ready just to sell the darn thing. Dont want to, but its becoming more trouble than its worth

 

check the starter wire, the big red one, make sure it's not pinched and grounded to the frame somewhere.

 

The starter wire is in really good shape, no knicks in the insulation anywhere on the wire.

The only wire that looks somewhat questionable is the positive wire on the battery, but that is only because it has heated up due to this issue and the insulation at the connector to solenoid has melted a bit.

My cousin who is a mechanic keeps saying it has to be something easy. I've eliminated everything easy though.

Bad ground from block to frame? I'm running out of ideas here!

 

ok, so here is a stupid question. I have not replaced the fusible link wire from alternator yet. I have it off the solenoid and wrapped to keep from shorting on ground.

Lets say the alternator has a shorted diode or something. Even though the fusible link wire is unhooked from the solenoid, is it possible that the alternator is still shorting out the electrical system? According to the wiring diagram i have, if you disconnect the fusible link, the alternator itself is out of the loop. But...i have been wrong before!

 

My guess is that the massive starting amperage is dumping straight to ground, but you seem pretty sure you've eliminated that. Can you turn the engine over with a breaker bar on the dampener bolt? I would try to turn the engine over manually with a breaker bar while it's in neutral and see if you can. Then I would try to put the truck in 2nd and push it with another vehicle and see if that doesn't skid the tires. If it's not an electrically sourced problem then either the motor or the input side of the transmission is seized (I'm guessing). It's possible that neither the motor or tranny input is seized but that part of the clutch or flywheel became locked against the bellhousing during the reinstall. These tests will uncover that possibility.

If you can turn the motor over with a breaker bar, and pushing the vehicle in gear turns over the motor also. Then take the alternator off and have it tested, replace the fusible link, and try to do a push start. If it push starts doing that and runs fine, then it would almost certainly have to be the starting amperage getting dumped directly to ground somehow.

 

Ignition switch?

The Pos cable from the battery going straight to the starter will eliminate everything in between, including the alternator, the solenoid, the coil, the V.R., etc....

The only thing getting power that way is the starter itself. So the question is, does the engine turn over (at this point should not get any spark to the coil) when turning the ignition switch to start? If so, the starter is not the problem, and the engine is not seized. If it does not engage, the problem is the starter, or the starter drive gear is not lining up with the flywheel, or if it does, the engine is seized since it won't turn over. So what does it do at this point? Because from there, it will base what the next thing to do will be.