Battery Terminals Melting

[Rust Merchant]

I have a 1929 Sport Coupe. I have read lots of posts and can't find a specific answer.
I just got it a couple of weeks ago. It has been in the family for 25 years but has sat around quite a bit for 15 years. When I picked it up, it was dead. Pull started very easily. Started up and ran fine next day. A few days later, it would not crank. Totally dead. I bought a new battery, because the existing one was 12 years old. (Positive Ground) Hooked it up and still nothing but a click.
Pulled the starter switch, it was dirty, cleaned it up, and the copper contact on the starter.
Hooked terminals back up; immediately melted the neg terminal that bolts to the starter!
Replaced end on neg side. Cleaned the pos connection and replaced the end for good measure.
Re-connected and started to get smoke from the ground side!
Pulled starter, it is free. Bench tested starter; spins free
Looked at ignition switch, pics attached, it appears to be an aftermarket; not the original pop-off. I'm currently going through looking for a bad wire or ground, using a wire diagram.
I'm thinking that the starter switch is bad.
I cannot test the system because it goes up in flames when I connect the battery!!
My skill level is moderate +. This is my first Model A, but I have a 49 F Series with a flat head, and have been working on old cars for 30 years. Any ideas?

 

[Jim/GA]

To draw that many amps, to melt the end of a battery cable, the problem is in or around your starter switch (on top of starter), not the ignition switch (shown in photo).

Carefully remove the starter switch from the starter and you will probably find evidence of a direct short in there.

 

[jmeckel]

Use a ohm meter and check for shorts to ground. I would guess that the insulation on the starter switch is bad.

 

[Tom Wesenberg]

I would bet the same as Jon. Make sure the first nut is tight on the starter switch stud, so when you place the wire and starter cable on and tighten the top nut you won't spin the stud. I like to place the lighter wire terminal under the heavy battery cable terminal.

 

[Smurkey]

It's probably the switch. I restored a Ford 8N tractor with all new wiring (no fuses) but kept an old light switch. As soon as I pulled the switch out the whole wiring system went up; took only seconds. The insulation melted and shorted out independent of the switch and it was all ruined and I couldn't stop it until I could disconnect the battery which was all nice and tucked away with tight terminals. Needless to say when I replaced the wiring AGAIN I added a fuse and replaced the light switch.

Test the switch with a continuity tester. BE CAREFUL before putting power to it again.

 

[Rust Merchant]

Thanks for the replies!
The starter switch stud was loose so I tightened down the bottom nut. The switch looks like it has been very hot inside. The thread condition is not very good where the cables attach; won't snug down nice and tight. New switch being ordered from Snyder's today!!

The starter itself smells like burned wiring and the contact is pitted. When I bench tested it, it spun immediately and freely. It didn't spin as fast as I thought it would though. I expected it to really whiz. Does that sound normal?

I think I'll replace ground strap too since it looks pretty old and somewhat unraveled. The neg cable looks to be the correct gauge but pretty old. I might just do that one too.

I can't find evidence of burned wiring anywhere else.

 

[Rust Merchant]

Since you have the starter off, and you are ordering parts anyway, it might not be a bad idea to disassemble the starter to inspect it internally. You might find it is time for bushings and brushes. Or you may find problems internally that relate to your burnt wiring smell.

Good idea Ed. I'll do that. I have been looking at an exploded diagram of the starter and it looks like a rebuild is something I can tackle.

 

[Brentwood Bob]

You might want to add a second ground cable from the original frame attachment to the transmission top, or best, to the bell housing. This should improve the ground to the motor.
Loosen and then retighten one of the starter to flywheel housing bolts at the same time. Bob

 

[Marco Tahtaras]

I wouldn't be in a rush to do more then a visual inspection of the starter internally. They almost never fail unless they've been worked on! What you DO want to check is to be sure the starter shaft spins true. Many are bent from folks starting the car with the timing advanced and having the engine kick back against the starter drive. That will make the starter more prone to jamming.

As far as the new switch on order, unless they been improved in recent years, they are prone to failure. From reports here and elsewhere it would appear the switch contact is poor material with insufficient spring pressure. This makes it more likely to fuse to the copper starter contact. They may also have a problem with the threaded post moving and shorting against the housing which is what it sounds like what happened with your current switch. Others can possibly add more info first hand. I haven't used a "new" switch since the 1970's

Lastly, it's obvious your starter contact has been "dressed" with a file at one time or another. This not unusual. It is very important that the contact be as true as possible and mate with the switch contact evenly over a broad area. There is a huge current draw there. The smaller or more irregular the contact area is the more likely it will arc. The more it arcs the more it eats away those surfaces further reducing the contact area. The cycle continues and degrades the area until the arcing is bad enough to fuse the two together.

 

[gweilbaker]

Be cautious of the repro switch, the spring material may need adjustment(bending) to work. They are not made like the original material and are soft. They will work, just throwing you a heads up.

 

[1931 flamingo]

On a repo starter sw I acquired there is an "insulator" sheet that extends from the contact to prevent the sw from touching the sides of the sw housing.
You might 'look" around for something directly shorting somewhere if you're developing that much "heat". Maybe the cable going to the starter sw has rubbed thru at the brake/clutch pedals depending on how it is routed. JMO


Paul in CT

 

[Rust Merchant]

I wouldn't be in a rush to do more then a visual inspection of the starter internally. They almost never fail unless they've been worked on! What you DO want to check is to be sure the starter shaft spins true. Many are bent from folks starting the car with the timing advanced and having the engine kick back against the starter drive. That will make the starter more prone to jamming.

As far as the new switch on order, unless they been improved in recent years, they are prone to failure. From reports here and elsewhere it would appear the switch contact is poor material with insufficient spring pressure. This makes it more likely to fuse to the copper starter contact. They may also have a problem with the threaded post moving and shorting against the housing which is what it sounds like what happened with your current switch. Others can possibly add more info first hand. I haven't used a "new" switch since the 1970's

Lastly, it's obvious your starter contact has been "dressed" with a file at one time or another. This not unusual. It is very important that the contact be as true as possible and mate with the switch contact evenly over a broad area. There is a huge current draw there. The smaller or more irregular the contact area is the more likely it will arc. The more it arcs the more it eats away those surfaces further reducing the contact area. The cycle continues and degrades the area until the arcing is bad enough to fuse the two together.

Thanks Marco! This is the starter switch I have been looking at:
http://www.snydersantiqueauto.com/3570

Can I smooth out the contact with a DA on a die grinder? Should I do anything to it?

I also found this interesting safety fuse:
http://www.snydersantiqueauto.com/3575

I will bench test the starter again and observe the shaft to see if it has any wobble.

 

[Rust Merchant]

Thanks Flamingo. I cant see any breaks in the neg cable but it looks very old. May replace just for good measure.

 

[Rust Merchant]

Marco: I re-tested the starter. No wobble. There are some threaded stud kits, contact button kits, and even a safety fuse kit available online. Should I replace the button and try a stud kit in the existing switch?

 

[Rust Merchant]

Here is what I found when I took apart the switch. Signs of lots of heat!

 

[Tom Wesenberg]

The insulating board is shot and that's why it shorted to ground. When you make the first nut tight be sure the contact is centered between the sides. Try the new switch you have on order, and if you're not happy with it then look for a good original. If you can't find one locally, then give Bert's a call. 800-321-1931

 

[Rust Merchant]

Thanks Tom! Ordering today; I'll let you know what happens.

Dwight

 

[columbiA]

Replace theground strap with the correct one.Those clamp-on terminal ends are only a temporary fix as they will corrode between terminal & cable.

 

[Brentwood Bob]

You are also looking for the push rod receiver to be tight at the housing, yours was loose.
This would allow the receiver to be cocked and jam the blade. Keep the copper post as a replacement. It looks good.
Bob

 

[pwh]

I'm with Tom - The insulator between the switch and the starter body is suspect. Also you said that you removed the switch after the first trouble and then it melted down. Make sure the insulator is on properly and the screws are not replaced with longer ones. First hand experience!

Phil