M38A1 starter won't engage flywheel - am I missing something

wilfreeman · Post by **wilfreeman** » Wed Oct 12, 2011 1:05 pm

Alright, I got my new wiring harness installed and tested everything I could (as far as lights and guages are concerned - my horn blows any time I touch the ground wire to ground though). I tried the starter and nothing - but then after I checked, I noticed the contact spring wasn't moving. Turns out the contact shaft was rusty, not allowing any movement. Got that cleaned up and working correctly. Now, the starter turns great, but the pinion won't engage the flywheel. I removed and installed the starter 4 times checking this and that, but still no engagement. The pinion moves all the way upthe shaft when the lever is pushed (on the bench). I adjusted the screw from touching the contact shaft all the way out to the point that the contacts weren't touching (starter motor won't turn). I am waiting on the wife to get home to push the plunger while I watch it - maybe I can see something from that angle.

On the horn, would that be a bad switch? I switched the wires on the switch - same result. I didn't even think about touching the wires together to take the switch out of the equasion - I'll do that now.

RICKG · Post by **RICKG** » Wed Oct 12, 2011 2:01 pm

Your starter is of the closed-nose type like this??

wilfreeman · Post by **wilfreeman** » Wed Oct 12, 2011 2:11 pm

Yep, that's it. My wife got home and helped me out - it was turning after all! I had taken the plugs out, so there is little resistance - when she pushed the pedal while I was watching I saw the fan turning! That sure was alot of extra work for nothing! At least I know how to remove /replace the starter easily now.

On the horn, I touched the horn switch wires together and it worked correctly. I removed the switch and hooked the wires back up - the horn worked correctly when I pushed the button. I felt up in the hole where the switch threads into, and thought that maybe the switch button is hitting the inside of the hole? Is there supposed to be a washer or spacer on the switch? I'll try to find it in the TM.

RICKG · Post by **RICKG** » Wed Oct 12, 2011 2:30 pm

Well now that's a GOOD wife.. she'll not let you forget
that she fixed it for you tho..

Any time i go out to the jeep barn my wife asks
if i'll need adult supervision

wilfreeman · Post by **wilfreeman** » Wed Oct 12, 2011 2:32 pm

I can't really tell in the TM - I guess I can check my parts jeep tomorrow if no one knows. At least I know the switch is good so I don't have to buy one of those!

wilfreeman · Post by **wilfreeman** » Wed Oct 12, 2011 6:02 pm

Got that right - she fixed it - it was her touch that did it! Of course, I wouldn't have figured it out without her pushing that pedal for me. I hope that now that I am close to getting it back on the road she'll keep a little interest in it. All my daughter wants to do is ride in it - when will it be done is the question.

wilfreeman · Post by **wilfreeman** » Wed Oct 12, 2011 6:22 pm

One other question on this starter. My jeep was running 12v when I bought it. I took the starter to have the bendix replaced back then (in '98). Would anything have had to be replaced to run it on 12v? I remember it turned over kind of slow, but that could have been the wiring too. The starter seems to run well hooked up to 24v with a new wiring harness.

Post by **wesk** » Thu Oct 13, 2011 12:12 am

If the starter was converted to 12 volt then it will spin like the dickens for awhile with your new 24 volt set-up but remember the longer you crank it and get it hot the shorter it's life will be. My M37 was a half arse 12 volt conversion with the 12 volt starter in it. I have been running it a year and a half now with 24 volt set-up. Spins like a wild dog and fires her up every time but I have the correct 24 volt starter waiting on the shelf. The high RPMs will usually wipe out the Bendix in a year or so.

Just the Jam Nut.

wilfreeman · Post by **wilfreeman** » Thu Oct 13, 2011 6:21 am

Yup, missing the jam nut - guess I'll either have to take the one off the parts jeep or find a replacement. So what do they change when they convert the starter to 12v? Maybe I'm lucky (I doubt it) and the P.O. did the 12v conversion himself and did it half as*ed. Will a 24v starter run on 12v?
I took my spare starter to a local auto electrician (one of the brushes was broken off at the termination point to the coil). He said the brushes on a 24v are made of a different material. Does this sound right? He also said he was booked up for a week and a half so he couldn't get to it to change the brushes 'til then. I see that the brushes are crimped down at the termination point to the coil - how do you open this crimp up to change the brushes? The inside of this spare starter looks brand new (still painted red with little wear), so I'd like to fix it, but hate to pay for a full rebuild (the electrician said he didn't know what would be involved, so he couldn't quote a price - I don't do business that way because I usually end up paying wayyy too much).

Post by **wesk** » Thu Oct 13, 2011 11:05 am

The TM 9-1825B Auto-Lite Electrical Component overhaul manual contains the answer to those questions. Each portion of that manual applicable to the M series Willys are free to download in our downloads section. The starter section is at thsi URL:
http://www.willysmjeeps.com/v2/modules. ... tit&lid=99

wilfreeman · Post by **wilfreeman** » Thu Oct 13, 2011 8:07 pm

That's some good info there, although the starters described are early ones. It says: Unsolder and unclinch brushes from field coil. Insert new brush cable in field terminal, clinch tightly, and solder with rosin core solder.

Any ideas on how to unclinch the field terminal? My original thought was to use vise grips, but that didn't work. I didn't try grinding a hook on the end of one of the jaws though - that might work. I'm sure there's a purpose made tool for the job, but that's no fun!
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Post by **wesk** » Thu Oct 13, 2011 8:19 pm

When I find a soldered and clinched terminal I often drill right into the solder and copper wire which gives me a place to pry from.

The two starters used as examples and shown in the illustrations are the MBP-4301UT (early M38) and the MCS-4301UT (Late M38 and all M38A1/M170). They are both completely covered.

wilfreeman · Post by **wilfreeman** » Thu Oct 13, 2011 8:36 pm

Thanks for the continued help Wes! I'm going to get the starter back off the shelf tomorrow and get another look at it and maybe a picture to share of my problem area. Also, on the horn switch - I looked at my parts jeep steering gear and it didn't have a jam nut on the switch either. I was screwed all the way up tight to the steering gear. I'll try screwing mine in to different depths to see where it should be (I should have tried this already I guess).

wilfreeman · Post by **wilfreeman** » Sat Oct 15, 2011 7:58 am

OK, I tore the starter down to the case/field coil level and got the remaining brush unclinched/unsoldered. Now, where can I order a replacement brush set from? I cut a notch in the tip of the lower jaw of a small pair of vise grips with a Dremel tool cutoff wheel to unclinch the joint - worked like a charm!

I screwed the horn switch in until it worked by using the button and I have about 3/8" of space (just enough for a jam nut - go figure)!

Post by **wesk** » Sat Oct 15, 2011 11:53 am

For the horn just connect an ohm meter across the switches two wires. Depress the button at the top end of the switch to confirm that the ohm meter shows continuity and the switch does work and close. Have a helper hold the horn button down tight. Now screw the switch in until the ohm meter shows continuity (switch contacts have closed) then go one more turn. If the switch bottoms out before closing, your actuator rod in the column is bent or too short.

Starter brushes are a very common item. Most MV vendors carry them and you should be able to get them at your local auto-electric shop.
MCS2012S 4 brush set. Consisting of:
MCS1034S 2 EA brush
MCS12 2 EA Brush

Alternate numbers: 7369889, 5977-00-736-9889

Google the set number:
http://2825.iso-group.com/Public/PartDe ... 56864.aspx

http://www.partslogistics.com/demo/sear ... 2012S.html

http://www.wbparts.com/rfq/5977-00-736-9889.html