Starter Problem

[kirkcudbright]

When it rains, it pours. Another problem.

1950 Cub, 6v System

Last night, I am running the tractor for a few minutes. Everything is good. Shut it off and go to start it again - nothing happens.

The starter acts like it is getting no juice. It doesn't turn nor act like it wants to turn. Not a speck of movement.

I double check connections at battery and starter - no change.

I check battery voltage, and it is 6.3v - not great, but okay. I keep it on a float charger, and that is normally adequate. While I'm at it, I pop open the cells, and none are low.

I check voltage between battery and the starter - 6.3v.

I put the tractor in high gear and rock it back and forth - in an attempt to move the transmission a bit. No change.

I pull the starter out and see that it turns freely - I've never looked inside of one, and I don't know what is good or bad - but nothing is obviously broken or disconnected. The copper contact looks clean.

I try to run it with jumper cables directly from the 6v battery - nothing happens.

Today, I take it to a starter shop. The guy take off the outer band and looks inside. He says it seems to look decent. He jumps it from a (12v) battery, and it works fine. He says it seems okay from a quick inspection. When I say it wouldn't jump from my 6 volt battery, he seems skeptical. He tells me to double check my connections.

I take it home and try to jump it from 6v again - nothing.

I suddenly wonder if it is intermittent or if I am jumping it incorrectly. So I try to jump it with 12v from the truck - it works. Immediately try with 6v battery again - nothing. Double-check battery voltage - still 6.3v (same as it normally is).

Bottom line...
Works fine when connected to 12v battery.
Does nothing when connected to 6v battery (that it has been using regularly).

Ideas?

[clodhopper]

Are you using the same (6V) battery every time? have the meter attached when you test the starter, and report back the voltage under starter load...

[jlmason81]

Where did you hook the jumper cables at on the tractor side? Sure sounds like a ground issue. Have you checked your ground cable that is connected to the battery box?

[lazyuniondriver]

When it was bench tested was the manual switch connected to the starter rod removed? Have those contacts inside that switch housing been serviced or examined?

[kirkcudbright]

Where did you hook the jumper cables at on the tractor side? Sure sounds like a ground issue. Have you checked your ground cable that is connected to the battery box?

I checked for that, but you may want to double-check my methodology.

Starter completely removed from tractor
Positive battery terminal to exposed metal of starter
Negative battery terminal to copper contact on starter

Also, 6.3 volts from battery negative to battery positive and 6.3 volts from battery negative to tractor body (positive ground).

[kirkcudbright]

When it was bench tested was the manual switch connected to the starter rod removed? Have those contacts inside that switch housing been serviced or examined?

When tested, the contacts were removed and bypassed. Under 12v this works. Under 6v, it does not.

I did not put a meter on them, but a visual inspection showed clean contacts and what looked like a good physical connection when the lever was pushed.

[kirkcudbright]

Are you using the same (6V) battery every time? have the meter attached when you test the starter, and report back the voltage under starter load...

I did use the same battery each time, and I am starting to wonder about it. I don't know how old it is, and I don't know how it acts under a load.

I will have to double-check this over the weekend.

[danovercash]

6.3v is good for a fully charged battery. It should not fall under 4.5v when cranking. If it does battery is not holding charge. Been cranking mine with 6v for 49 years.

[FCUBMAN]

Could be a fine film on the commutator, try cleaning it. Weak brush springs might do it, too.

[Eugene]

Battery problem or cable or grounding problem.

Voltage drop test the battery. Multimeter (DC Volts) on each battery terminal. Check voltage. Engage starter checking battery voltage. See Danovercash's earlier post.

Clean up all connections. Clean - not check.

[kirkcudbright]

After last night's replies, I felt pretty comfortable the battery was going to fail a load test. Today, I took it in, and it tested good for voltage and under a load.

Removed from tractor and jumped with 12v battery, it works.
Removed from tractor and jumped in same way with 6v battery, and it doesn't do a thing.
When jumping it, the connections are to the case and to the copper contact on top.

Monday, I am taking it back to the starter guy.

Will post what he finds this week.

[Scrivet]

.....Removed from tractor and jumped with 12v battery, it works.
Removed from tractor and jumped in same way with 6v battery, and it doesn't do a thing.
......

And the size/gauge wire of the jumper cables is???????

1. Keep in mind 6V likes heavier wires. 12V will work great on smaller size wires which is one of the reasons for the change all those many years ago. Less copper in the wire means less expensive.

2. Most jumper cables are longer than the normal battery to starter cable. Makes getting enough 6V AMPS through the smaller wire even tougher.

3. You are not getting much contact area between the clamps and the starter nub and the clamp and the starter case. Usually a couple pointed teeth in the clamp. So even smaller spot for 6V AMPS to get through.

Your "test" with the jumper cables could very well be complicating diagnosing the problem by sending you in the wrong direction by thinking 12V works and 6V doesn't. If it'll spin on 12V it'll spin on 6V if you get enough AMPS to it.
As has already been suggested several times clean the connections.
Save the trouble of taking the starter back to the starter guy and spend the time removing, cleaning, and putting dielectric grease on every connection.
Remove both positive and negative cables from the battery and shine up the post and inside the terminal.
If you have replacement cable clamps take them loose and shine up the inside clamping portion and take a wire brush to the end of the cable.
Take a wire brush to the starter end of the cable until it shines on both sides.
Wire brush the starter lug till it shines.
Wire brush the other end of the positive cable, both sides, yep, till it shines!
Wire brush where it bolts to till it shines! Is it to the battery box? Then make sure the battery box is solid. Then take out one or two bolts that hold it to the tractor and make where they touch the box shine. Make the bolt shine.
Make the ears on the starter around the bolt holes shine.
Shine the flats around the bolt holes for the starter mount.
Start your cub and go for a drive.

[Eugene]

I was planning on waiting for the results from the second trip to the starter repair shop before posting again.

Removed (starter) from tractor and jumped in same way with 6v battery, and it doesn't do a thing.

At a minimum you should at least get a hum and/or some vibration from the starter.

Starter good, battery good. Common denominator - battery cables - jumper cables.

Scrivet's and previous posts on cleaning up connections and checking condition of the battery/ground cables is valid. Battery cables do corrode inside the insulation.

[kirkcudbright]

SOLVED

One of the field coil screws inside the starter had loosened.

Starter-guy tightened it up, and everything works fine now.

Thanks for all of the help.

[clodhopper]

Glad you got the problem solved.