Joined: Nov 01, 2019 Posts: 12 Location: Story, Wyoming
Posted: Tue Apr 07, 2020 9:47 pm Post subject: M38 Oil pressure gauge line AND Engine Temp Connection
I tossed the Oil gauge and the Temp gauge when I got this jeep, because they were not original. I bought the reproduction gauge that had the Douglas connectors, along with a oil p. sending unit. I'm not sure how these are connected now. I'm assuming I need to buy some wiring loom? and some male electrical ends? Is there an actual wiring cable for these two guages and corresponding sending units?
I'm sure the answer is right in front of my nose.....
A _________________ Adam Jahiel
M38A1 & M38
If your Jeep is stock military 24V electrical & 24 V waterproof harness then you need do nothing and just connect the correct #33 (water temp) & #36 (Oil Press) wires to them.
If your M38 is not stock and/or has a butchered harness then we can offer little help without you first posting photos of both sides of your engine, firewall harness, harness between firewall & dash and a closeup of the back side of your instrument cluster.
The manuals that should be on your work bench right now are the M38 parts manual ORD 9 SNL G-740 (you need to review the engine illustrations, the harness illustrations and the instrument cluster illustrations). and TM 9-8012 your primary M38 service & operations manual for the same illustrations and the detailed wiring diagrams.
I replaced the oil sensor with one I got from DeBella. I'm not sure how it is humanly possible to get a wrench on those things, but I managed with only a slight amount of skinned hands and arms. I may have to remove it again after I order the proper holding bracket that bolts onto the bell housing area.
The temp sensor is definitely not original. Can I use the existing setup, or might it read incorrectly? No idea if there is a difference or if, like the oil, it needs to be a matched set.
I want to say thank you to Wes and everybody for this incredible site. I can't say how helpful, interesting, motivating, and fun it is. _________________ Adam Jahiel
M38A1 & M38
Joined: May 30, 2014 Posts: 2981 Location: Texas Hill Country
Posted: Thu Apr 09, 2020 7:12 pm Post subject:
There were two M38 temp gauges and senders. If you have the early M38 temp gauge with resistor on the back it takes a different sender than the later unit. Brent Mullins in College Station has them NOS in the package.
Adam, You really need to better inform us what you have on your M38 before we can intelligently offer you advice. What Oil Temp Sender do you have? Is your m38 stock 24V or modified to 12V? The aftermarket gauges you removed were what brand & model? _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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