Posted: Thu Nov 09, 2023 7:02 pm Post subject: 1952 M38 Slow Starter
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?
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. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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?
Last edited by JeepdaddyRC on Fri Nov 10, 2023 3:10 pm; edited 1 time in total
Looks like you need to open up the kick switch and evalaluate the condition of it's contacts. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Which part number starter do you have? I believe that at least one of those kick switches have available new internal contacts sets. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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?
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.
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.
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. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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.
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