Just installed overdrive solenoid and now my coil is overheating and car wont start any help?

So I bought a 1951 Ford shoe box with the original 239 flathead in it it came running quite nicely with 3 on the tree with overdrive however overdrive was not hooked up. I installed selenoid and wired kickdown switch etc Andover Dr came to life without any problems. However yesterday while driving the car died at an intersection put it out of the way and discovered that the engine coil was extremely hot as well as the ignition switch was too hot to touch. after some investigation I discovered that the wire running from the coil to the kickdown switch was on the positive pole instead of the negative pole of the coil. I switch to those over and engine came to life and I took off to test it out returned home after about 10 minutes of driving to find coil extremely hot again. any idea as to what is going on here? I don't want to keep replacing these damn coils.

 

The over drive may have been disconnected for this reason. Disconnect it again to see if the problem goes away.. Baby steps.

 

are you going thru a relay? if not thats your problem pulling too many amps for the circuit . google ford over drive wiring and see how its hooked up .

 

First thing--- ***uming you're on original 6V positive ground, if not, then all poles are reversed--- the kickdown wire was correctly wired to the (+) distributor side of the ignition coil. This wire momentarily kills the engine when you press the kickdown switch--- but only if the car is upshifted into OD at the time.
The second OD wire to the coil goes from the (-) side of ignition coil to the IGN terminal on the OD relay. This wire provides power to the relay from the ignition circuit. So, in total, there should be four wires at the ignition coil, two on each pole.

I can't see any way that the OD wiring could overheat an ignition coil, at least not any time that the engine is actually running. The only time a coil overheats is if it is powered up with the engine NOT running, unless you simply have a bad coil or the wrong coil. If it was shorted to ground, the engine wouldn't run at all. I think you may have other problems, including the possibility that you simply have a bad coil.

 

Follow the Ford wiring diagram. You may also have a broken coil wire in the solenoid causing a short.

 

Just a quick follow-up. The schematic above differs from my description a bit (mine is from '51 Mercury schematic). On mine the OD relay gets its power from the coil IGN terminal. On the schematic, it gets power from the ACC terminal of the ignition switch. The results are basically the same, that is that the relay only gets power when the key is on.
Another comment to Frozenmerc, if there was a short in the solenoid wire, the engine would die but that wouldn't overheat the ignition coil.

 

You'd think the 30 amp fuse on the relay would blow.

 

This is exactly why the kickdown wire is on the (+) distributor side of the coil, because it could kill the engine just as effectively on the other side of the coil, however that would be a true "short". Even though the kickdown exposes the circuit to a contact to ground, it really isn't a "short" (defined as no resistance) because the coil acts as a resistor in between.

 

Thanks for the responses. . Btw I should have said it's a 12v system. I replaced coil and that seems to have done the trick. .for now. .haha. .. however i ohm tested the old coil against the new one and they were identical.... so I'm even more confused as to what is going on. .

 

Guess I'll see how long this lasts and go from there. I bought this car and it's a wiriing nightmare under the dash. All red wires going to power windows compressor etc... I need an electrician. ..lol

 

This might be a stupid question, but I run an OD on my old Volvo, we have a relay in between, controlled by a switch that does the on and of function. It's under constant power when it's in on mode. And you just pull lever to off, no power and it shift down/out.

But what is the purpose of the kickdown switch and gouvernor? Is the governor a lock out switch?

 

The governor only lets the overdrive work after the car is up to a preset speed.

 

Okay, we use a lock out to ensure it being used 4th. English cars run them in 3rd and 4th, it's common to disconnect the lock out, and run them like split in a truck.

But is the kick down a switch, or em I misreading the diagram?

 

yes

 

I've never fooled with an overdrive, but if it is an original unit wouldn't the kick-down solenoid be 6 volts?

 

the kickdown cuts current to the points so the od can shift down into normal 3rd gear. a 6v sol. will run on 12v but will get "warm."