Joined: Oct 02, 2014 Posts: 2059 Location: South Carolina, Dorchester County
Posted: Sat Nov 18, 2023 9:17 am Post subject:
Sorry, no. That doesn't explain it.
Check your ORD9, illustrated.
Same mount is used on all M38 engines.
Without the extra steel wrapping on yours, if the rubber were to come unglued I think the fan would start chewing on the radiator pdq, or worse. _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Appreciate the good catch RonD2. Another project to add to my list. Looks like these have been there for some time without failure. But sounds important to install correct mounts.
What you have are the much cheaper old CJ mount rubbers. The RMCXXXXX engine serial simply put is a brand new factory replacement engine that was built several times and serialed RMC instead of MC because they were shipped under contract to the Military as replacement engines. The MC serial means you have an engine that was originally installed ian an M38 chassis on the assembly line. Since RMC engines were shipped along with groups of M38's as requested by the Army so they would have in stock new replacement engines when the need arose. This means the odds are in favor that your RMC engine was installed in your M38 most likely while it was still in the military. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Really appreciate the help. Well you guessed it, no engine stay cable. So it sounds like the RMC engine was likely installed during its military service life. Then it was rebuilt at some point and incorrect CJ mounts were installed and stay cable not reinstalled.
Is replacement of the motor mounts in the manual? Not sure how to handle the radiator and its support brackets.
Honestly, is it realistic for an old guy to replace those engine mounts by himself on a cold WI garage floor with a transmission jack or floor jack under the oil pan skid plate? Concerned about the radiator clearance and those radiator support brackets as the engine moves upward.
Joined: Oct 02, 2014 Posts: 2059 Location: South Carolina, Dorchester County
Posted: Sat Nov 18, 2023 7:33 pm Post subject:
JeepDaddy,
So as to not muddy this starter issue thread too much, I suggest starting a new thread topic "Changing M38 Front Motor Mount Cushions".
In the meantime, I'd also suggest reading Paragraph 116 starting on page 122 of TM 9-8012.
Not every step will be necessary, and some steps can be "tailored", but all the main points of concern are covered.
JeepdaddyRC wrote:
Honestly, is it realistic for an old guy to replace those engine mounts by himself on a cold WI garage floor with a transmission jack or floor jack under the oil pan skid plate?
Well, I'm 68 and wouldn't hesitate to do it, but my garage floor isn't as cold as yours.
Pretty sure most of it can be done standing up.
See you over on the new thread topic. _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
To bring this thread about my slow turning starter to some conclusion, I have completed the following:
1. Replaced starter switch with NOS
2. Removed the old chassis to engine block ground strap, cleaned all mating surfaces to bare metal, and replaced with new ground strap
3. Added the missing front starter support bracket and cleaned all mating surfaces to bare metal
Ohm meter resistance check from battery negative terminal to engine block and starter housing = 0.2 ohms.
Is that too high? Still have a weak ground, or is that within specs?
Joined: Oct 02, 2014 Posts: 2059 Location: South Carolina, Dorchester County
Posted: Tue Nov 21, 2023 6:04 pm Post subject:
JeepDaddy,
It depends, but in my experience, anything under 10 ohms is a "good" ground.
The "depends" variable is the type of meter (quality, calibration) and the gauge size and length of the wire or strap you're measuring.
For peace of mind, use the meter to measure the resistance of the wire or strap BEFORE installing it.
Only use the meter leads to touch the piece (no fingers holding contact).
Once installed, if your connections are clean and tight, measuring again should yield pretty close to the same resistance.
Achieving true zero ohms resistance in anything is impossible.
If it were possible, we'd be driving Jetson's cars...... _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Having re-read all three pages I must take a moment and ask if you have ever checked your ignition timing accurately. 10 BTDC is the norm but some folks have convinced themselves that 15 BTDC or more is needed with unleaded gas. Excessive advanced ignition timing can cause the laboring starter syndrome also. If timing is dead on 10 then based on everything you have done so far it would be time to remove the starter and take it to a local auto-electric shop at least for a bench check but a teardown inspection should also be considered. Depending on the age of your local auto electric shop and it's workers they may or may not have the needed technical data on hand so I usually carry a thumb drive with the the jeeps TM set, IPL and TM 9-1825B to help them with specs. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Re-checked timing. I have the raised bump on the cover and hole on inside of pulley. It’s awkward to get a clear view at the correct angle, but it looks like 10 degrees BTDC.
Went to starter rebuilder. Showed him the following video. The video shows 2 voltmeters. Left is battery voltage, right is voltage at starter. Voltage is the same while cranking, but drops to 12 volts. He claims it’s a battery problem not a starter problem.
Reminder: New starter switch, batteries charged and equal at 12.6, all connections cleaned, new ground strap. Does this indicate I need a starter rebuild or new batteries?
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