Correct Oil Pressure monitoring

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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Yarder
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Correct Oil Pressure monitoring

Post by Yarder » Sun Apr 10, 2011 7:17 pm

I have an early 1953 M38A1 with the thumb screw battery box, the diagonal fender seams, and a hinged radiator. I'm doing the restoration myself.

I finally figured out why my Oil Pressure gauge wouldn't work. I checked cable continuity, good solid connections, no shorts on the rubber insulators, good ground on the oil pressure sensor, open oil lines to the sensor, good ground on the sensor and even soaked the sensor overnight in gasoline to loosen up crap inside preventing it from making any readings.

When I had the sensor off, I noticed some text on the side of the sensor. 60 lbs. Funny thing, my gauge is a 120 lb meter.

So, what do you all recommend? Change out the gauge or the sensor? What gauge is correct for my jeep? I am assuming that a 60 lb sensor is not compatible with a 120 lb dial.
1953 Willys M38A1, SN 52612


Joe Gopan
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Re: Correct Oil Pressure monitoring

Post by Joe Gopan » Mon Apr 11, 2011 5:17 am

Sender rating must match the gauge. Around 1955 the Army ordered trucks with 60# Oil Pressure Gauges, the 120# Guages do not give accurate readings, the existing M-38 and M-38A1 Jeeps with 120# Oil Pressure Gauges would get the update to 60# when the Jeep was sent to a support unit for maintenance. Not all Jeeps got the change. There are bulletins and MWO's referring to the upgrade and the responsibility level of the shops authorized to make the change.
My advice would be to install a 60# Gauge in order to get more accurate reading.
Instructors on M-38/M-38A1 Jeeps advised students that the 120# Gage was not accurate, and that as long a the 120# Gauge moved it was indication of sufficient oil pressure.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

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Yarder
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Posts: 135
Joined: Tue Dec 02, 2008 9:35 pm
Location: Seattle, WA

Re: Correct Oil Pressure monitoring

Post by Yarder » Mon Apr 11, 2011 6:46 am

When I energize the jeep, I do get a little wiggle out of the 120 gauge hooked up to the 60lb sender. So, I'm assuming that everything works right.

Since I have the 60 lb sensor, I'll go for the 60 lb gauge.

Thank you!
1953 Willys M38A1, SN 52612

Joe Gopan
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Re: Correct Oil Pressure monitoring

Post by Joe Gopan » Mon Apr 11, 2011 6:49 am

Good decision.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

Re: Correct Oil Pressure monitoring

Post by Joe Gopan » Mon Jun 05, 2017 3:37 am

Senders must match gauges.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO


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