intermittent dead starter
 

I'm having an intermittent problem with the starter acting like it has no electrical power. I can jumper direct to the copper pass through and it still won't run, but most of the time it will turn the engine over nicely. So far it hasn't stranded me, but I know my luck will run out. Probably in front of an admiring crowd. :p

My thought is that there is an open winding that periodically ends up under the brushes, but I figure the forum will have some suggestions. I may take it off the car tomorrow for a closer look.

The battery is currently at 6.8V and the solenoid is closing with a solid click. All the connections between battery and starter are showing good voltage, but the starter is not pulling the battery down at all, so no current is passing through it.

Thanks,

John

Re: intermittent dead starter
 

Hey John,
Two things come to mind with your symptoms.
First , I'd check the easiest first...starter switch contacts function.
Then , I'd pull the starter and look over the segmented copper (commutator) that the brushes ride on. A FLAT spot will act exactly as you describe. Next time that it happens, bump the starter several quick times to see whether that will bump it past the flat spot. Maybe needs a rebuild ?

Re: intermittent dead starter
 

Re: intermittent dead starter
 

tighten battery terminals tighten contacts

Re: intermittent dead starter
 

As I said, I've been through all the connections. A new piece of data though, it will crank over well with the battery freshly charged to about 7 volts. I think I'll take the battery over to the LAS and get it load tested.

With my ordinary run of luck, it will be the starter AND the battery. :mad:

John

Re: intermittent dead starter
 

When the starter won't turn try tapping on it with a hammer. Sounds like a hanging brush or a out of round commutator.

Chev. had this same problem a few years ago.

JB

Re: intermittent dead starter
 

What solenoid??

Re: intermittent dead starter
 

John, there is a shop in Marietta that I have been using for over 50 years. They still know how to work on antiques. Call me if you need their address. Jim

Re: intermittent dead starter
 

If the starter switch contacts have been cleaned and are good, then I'd suspect the armature/commutator. The commutator can be checked with a VOM and the armature with a growler for opens. It appears there could be a dead spot in one or both.

Re: intermittent dead starter
 

Thanks for the advice. I'll get to spend some more time on it later this week and will keep you posted on what I find.

I agree, it's likely to be a dead spot on the commutator/armature. There's a local auto electric shop that still does old car work, so I may head over there and let a pro test it. It's part of the fun for me to figure these things out and fix them myself if possible.

John

Re: intermittent dead starter
 

Your brushes might be worn out. I usually find the two ground brushes wear out about twice as fast as the two field brushes. The ground brushes are easily changed by just removing the 2 screws and installing the new brushes.

If the 2 field brushes also need to be changed then you need a good size soldering gun, such as a WEN 250, or a large soldering iron.

Take a picture or make a drawing of where the 4 brushes fit, to be sure they go back in the correct location. Do not undercut the commutator if you have to clean it up.

Re: intermittent dead starter
 

Admit it, the starter need to be removed and repaired. Don't fudge about, just do it.

Re: intermittent dead starter
 

Come on now, procrastination is the key to flexibility. Besides, I'm gonna leave Bourbon and cookies out tonight for the wrench elves. :D

Tom, why do you say not to undercut the commutator?

Re: intermittent dead starter
 

He is talking about the mica between the commutator sections. A starter runs in short bursts not requiring the cutting like is done to the generator.

Re: intermittent dead starter
 

Hey Tom,
For many decades, I have 'undercut the mica' on both gen and starter commutators. Then finish by polishing a little. Never have heard that statement...'do not'. Matter of fact, a machine/device was commercially made to do the undercut :confused:

Re: intermittent dead starter
 

Because of the strong springs and metal brushes, the mica wears as the commutator wears, so it doesn't need to be undercut. I worked on a starter where someone had undercut the commutator, and some metal from the brushes and commutator had actually shorted the bars.

Generators have carbon brushes and weaker springs, so they get undercut about .010" or a hair more, otherwise the brushes can ride over the insulators and arc on the bars.

Re: intermittent dead starter
 

I know you checked the batt connections, but you better do a good job of it. Every connection. It can show good voltage with no load, but it can't pass the high current through. Also look at the connection of the batt cable to the terminal that fastens to the batt posts. If that crimp is rusty or loose, it can drive you crazy. You must have a good, tight crimp around the cable wires. I had to drive a nail in one to get good contact.

Re: intermittent dead starter
 

Tom, that's very interesting, hadn't heard about that feature, but that does make sense.

I have the starter in the hands of a rebuild shop right now and will let everyone know what transpires (Friday probably). This shop supposedly has a lot of expertise on both A and T starters and generators.

As far as checking the connections, I removed the starter contactor and jumpered directly to the starter connections with no resulting rotation of the starter. That removes all the intermediate connections. It is fairly obvious to check through all the connections to look for the open/loose one, including to check the frame/engine ground and battery ground to frame.

On the other hand when the starter had it in its mind to run, it would start the engine repeatedly. The auto electric gentleman was of the opinion (without having it apart yet) that the problem was likely a bad winding or commutator segment in the armature.

Thanks to all for the helpful comments,

John

Re: intermittent dead starter
 

Just one opinion from quite a few vintage past experiences:

The minute an 80+ year old properly "grounded" starter begins to drag or slow down while using a fully "charged" good battery, with all "clean" electrical connections, and a fully "operable" starter switch, it is always best to immediately further investigate the starter and not wait like that of many vehicle operators.

Slow turning "worn" starters begin to generate intensive heat which rapidly wears metal parts ...... they always get worse as time goes on ...... never better.

As starters continue to get hotter, (sometimes smoking), one day the starter will wear enough to die ...... hence, after far more damage is done.

Most common are commutator cylindrical level surfaces get worn down unevenly with worn uneven brushes, commutators get out of round, hard steel brush holders can later wear soft metal commutators in a jiffy.

On old vintage starters with unknown history:

1. Replacing old starter bushings with new greased starter bushings for under $5.00 is a steal.

2. Replacing starter brushes on old starters at under $5.00, once starters are dismantled can never hurt.

3. One can test for armature commutator continuity between commutator segments with a test lamp and repair old field coil tape with electrical tape.

4. With armature shaft set in (2) simple wood shaped vertical 1 x 4 vees, armature can be rotated by hand .... a flat mill file can be set up on level wood shims to correct an out-of-round and/or un-level worn soft metal commutator, followed by polishing commutator with fine sand paper.

5. Not much to it for a Model A handyman willing to try .... and ....... after careful completion .... your simple, starter re-build procedure can be as good as making a one (1) time $10.00 payment on a 50 year Life Insurance Policy.

Hope this helps.

Re: intermittent dead starter
 

Check the commutator is clean and the brushes are still good. Weak brush springs or a broken brush spring, or a brush hanging up in the brush holder will cause this problem. Also, check the commutator end bushing and the drive end bushing. Could be the armature is rubbing on the field pole shoes too.