Farm Equipment - 1951 CA starting / electrical problem

1951 CA starting / electrical problem

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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=196765
Printed Date: 25 Sep 2024 at 11:27am
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Topic: 1951 CA starting / electrical problem

Posted By: mosstrumpet
Subject: 1951 CA starting / electrical problem
Date Posted: 20 Aug 2023 at 8:30pm

Hello all,

I've got a head scratcher here. After doing a considerable amount of work on the tractor, full tear down and rebuilt head, exhaust manifold, coolant flush, inner and outer final drive seals, pulled and cleaned hydraulic pump, repacked rams, new hydraulic hoses, rebuilt carb, new sediment bowl, oil pressure gauge, thermostat and gauge, new brakes, and lastly a new coat of Allis Persian orange.

Original 6 volt generator and positive ground. I am having trouble with my starter. It doesn't spin or even hum. I checked for amperage at the starter terminal and have around 6.3 amps. I am using 00 gauge wire for ground and negative supply to starter. I pulled positive and wire wheeled the contacts points to ensure proper grounding. I checked ohms between positive terminal and the lock bolt hole for the starter and all is good here .3 ohms. I pulled the starter, I was able to get it to spin a few times on the bench and it had an odd grinding sound but no signs of wear. It stopped spinning entirely after this.

Took swing arm assembly off to inspect brass button and contact points. They were in working order.

Bendix visual inspection looks good, teeth on the drive gear are in good condition, no chipped or broken teeth (same on the fly wheel) nose cone in good condition. checked the armature Ohms where consistent in 180 test, side by side, and no continuity on the shaft - so I would say it passed. Checked the continuity on the brass button to the 2 brushes wired to it and both checked with similar ohms.

Last test I ran I put power to the brass button without the swing arm and still nothing.

Thinking I may have a weak battery I checked with my battery tester and it checked out with battery tester and multi meter.

By all the test I would assume the starter is in working condition with the strange grind noise, I have power where I should and ground where I need.

I am not interested in switching to 12 volt, I know there are some benefits but I want to try and keep it as original as possible.

Any thoughts would be greatly appreciated.

Replies:

Posted By: steve(ill)
Date Posted: 20 Aug 2023 at 10:56pm

If starter is on the bench and you put power to the brass button and ground the case.. It should spin.. dont matter what the bendix is doing... Its just a motor at that point.. If it does not spin, then you have a bad battery or internal problems... Grinding noise makes me think the starter needs rebuilt.. If the grinding is not in the bearing / bushings on the end of the shaft, then the rotor is rubbing the magnets as it rotates.

If you want to verify the battery, jump the starter with your 12v truck battery as a " test".

I was able to get it to spin a few times on the bench and it had an odd grinding sound but no signs of wear. It stopped spinning entirely after this.

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Like them all, but love the "B"s.

Posted By: steve(ill)
Date Posted: 20 Aug 2023 at 11:01pm

i have taken "WEAK" starters apart, sanded the commutator smooth and clean on a lathe, scraped the insulator betweeen the bars with a sharp thin knife, sanded the brushes flat on the face, make sure the SPRINGS are pushing on the brushes, oil the bearing and reassemble....... Not a " rebuild" , but often works.

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Like them all, but love the "B"s.

Posted By: Ted in NE-OH
Date Posted: 21 Aug 2023 at 9:08am

Could be that new paint is keeping you from getting a good ground at the starter.

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CA, WD, C, 3 Bs, 2 Gs, WC, I-400, 914

Posted By: TramwayGuy
Date Posted: 21 Aug 2023 at 9:19am

“.. If the grinding is not in the bearing / bushings on the end of the shaft, then the rotor is rubbing the magnets as it rotates.”

I had a starter that had a broken armature, and it would spin sometimes, but with heavy dragging. Acted like bad bushings.

Posted By: MACK
Date Posted: 21 Aug 2023 at 9:33pm

Brushes may not making good contact with armature. Worn, weak springs, or stuck. MACK

Posted By: Steve in NJ
Date Posted: 23 Aug 2023 at 7:26pm

If you have a grinding going on inside, best to have a rebuilder tear it down and access the problem. Do you have a good reliable rebuilder in town? If not, I offer rebuilding services if interested....

Steve@B&B

bb-customcircuits.com

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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife