1952 M38 Slow Starter

JeepdaddyRC · Post by **JeepdaddyRC** » Thu Nov 09, 2023 7:02 pm

Per Wes's troubleshooting guide from a previous thread, here are my findings:

1 - battery voltage reading with master switch off and all accessories turned off. I check this twice. once with the plus Volt Meter lead on the + terminal and the neg lead on the Neg terminal then again moving the negative lead to the chassis ground. 25.8 volts at neg lead and 25.8 volts at chassis ground

2 - Battery voltage reading at the input terminal (terminal A) on the kick switch with master switch off and all accessories turned off. 25.8 volts

3 - With master switch off and all accessories turned off, connect plus lead of your voltmeter to the output side terminal (I used terminal C) of the kick switch and neg lead to chassis ground. Manually engage the kick switch and record the voltage reading. 18.0 volts, slowly drops during cranking

Multimeter indicated continuity between input side (terminal A) and output side (terminal B) when the kick switch is NOT depressed.

Continuity between terminal B and C when kick switch NOT depressed,

So is there a problem somewhere in the kick switch mechanism?

Post by **wesk** » Fri Nov 10, 2023 1:02 am

B & C should have continuity as long as that copper tab is connected to both of them.

A & B should only have continuity when the switch is closed/depressed.

Since you show continuity between A & B with the switch open then you have burned or broken and shorted internal contacts. You will need to open the switch and determine if the problem is simply a carbon or melted copper buildup that causes constant contact between the contacts or if they have broken loose and touch each other.

This is is a common cause of battery run down over a few days since the leak is not enough current to turn the starter you never notice the leak until the batteries come up discharged over short non-use periods.

Let sus know what condtion the internal of the switch are.

If you need details of how to info go to TM 9-1825B 1952 Autolite Electrical Accessories Manual.

JeepdaddyRC · Post by **JeepdaddyRC** » Fri Nov 10, 2023 1:13 pm

With master switch off and all accessories turned off, and plus lead of voltmeter to the output side terminal of the kick switch (I used terminal C) and neg lead to chassis ground - should I see full battery voltage when engaging the kick switch?

I repeated the above procedure today after a night on a 24 volt battery tender. When I engaged the starter switch I had 19.5 volts. The voltage slowly dropped during cranking.

Would this cranking voltage suggest a bad/shorted switch?

Connected voltmeter between terminals A and B. Found 24.8 volts when kick switch is NOT engaged.

Here are some photos of the interior of the switch. What do you think?

Post by **wesk** » Fri Nov 10, 2023 2:57 pm

Looks like you need to open up the kick switch and evalaluate the condition of it's contacts.

JeepdaddyRC · Post by **JeepdaddyRC** » Fri Nov 10, 2023 3:12 pm

As always, thank you Wes!
Apparently, I was adding the photos when your message came in. See above.

Post by **wesk** » Fri Nov 10, 2023 7:43 pm

Which part number starter do you have? I believe that at least one of those kick switches have available new internal contacts sets.

JeepdaddyRC · Post by **JeepdaddyRC** » Fri Nov 10, 2023 8:55 pm

The info plate is obscured by thick OD paint.
The starter and switch look like the one above and the M38A1 starter.
Does that make it a late M38 and M38A1 Autolite MCZ 4001 UT?

Post by **wesk** » Fri Nov 10, 2023 9:33 pm

Yes.

The late starter is illustrated in the jeep manuals and parts are listed there but the late starter is not in TM 9-1825B dated 1952. The late starter has it's own maintenance manual TM 9-2920-215-35.

You can find the rest of this manual in my photo file: http://www.willysmjeeps.com/v2/modules. ... _album.php

JeepdaddyRC · Post by **JeepdaddyRC** » Sat Nov 11, 2023 3:13 pm

The contacts look rough. Any leads on a rebuild kit for this switch?
I see a rebuild kit for the early M38 starter switch, but not for the late M38 and M38A1.

JeepdaddyRC · Post by **JeepdaddyRC** » Sat Nov 11, 2023 8:33 pm

Working on cleaning contacts. One of the “house shaped” insulators is broken.
What material should I use to make a replacement?

Post by **wesk** » Sat Nov 11, 2023 10:35 pm

Phenolic sheet should work fine. I did note one of the contact ends of one stud were heavily goughed which will need to be filled and ground flat again. Also insure insulated washers are used where they are called for.

JeepdaddyRC · Post by **JeepdaddyRC** » Sun Nov 12, 2023 10:07 am

Source for 1.3 mm (.05 inch) phenolic sheet?

Post by **wesk** » Sun Nov 12, 2023 11:25 am

Just google Phenolic sheet for sale: https://www.google.com/search?q=0.05%22 ... s-wiz-serp

Post by **wesk** » Sun Nov 12, 2023 11:33 am

Here's a 12" sq. .047 sheet for $18

https://www.google.com/search?q=0.05%22 ... s-wiz-serp

JeepdaddyRC · Post by **JeepdaddyRC** » Tue Nov 14, 2023 3:07 pm

Could not get the second link to work to the $18 sheet.

Received a phenolic sheet from McMaster-Carr that was the correct thickness of 3/64 (.047 in). However, it is a "circuit board" with one copper-clad side. That side conducts electricity as confirmed by a multimeter. it was their only phenolic sheet available in 3/64 thickness.

The other face is non-conductive.

I assume we don't want this "reproduction insulator" to be conductive on one face inside the starter switch. Or, is it OK if the conductive side faces the exterior and not the interior plunger side?

Having trouble locating electrically insulating 3/64 (.047) phenolic sheet. If anyone has a source, please let me know.