Oil pressure

1950 - 1952, M38, questions, discussions, regarding anything related to the M38.
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chucks_toy
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Oil pressure

Post by chucks_toy » Sun Jun 28, 2020 5:58 am

One of my l134 rebuilt engines is slow to get oil pressure when it started. I crank the engine starts right up and at idle it takes a little time to build pressure. Once it has pressure, at idle it has 20 pounds and at the throttle, it goes up to 44. Any suggestions why it would be slow to build? I did not do the mechanic work.
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Joe Gopan
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Re: Oil pressure

Post by Joe Gopan » Sun Jun 28, 2020 7:41 am

Check the sender to see if it is for a 120# Gauge or 60# Gauge.The Oil Pressure Gauges for the 50's M-Series were not accurate.
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dpcd67
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Re: Oil pressure

Post by dpcd67 » Sun Jun 28, 2020 8:01 am

Before you run it any more, put a direct reading gauge on it like a ww2 gauge; then you will know if it is your engine or the gauge.
However, the last M38 I did, did the same as yours; 20 and 40 and I put a Melling pump on it and it now runs at 60 most all the time. Remember that the original M38 pumps are aluminum and I don't trust them. That can't be a good idea.
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chucks_toy
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Re: Oil pressure

Post by chucks_toy » Sun Jun 28, 2020 8:43 am

I put a gauge with a direct line to the block and still have the same results.
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Re: Oil pressure

Post by 11ACRLT » Sun Jun 28, 2020 9:30 am

That sounds like a weak pump or an air leak on the suction side of the pump. Could also be a clogged pick up screen.
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dpcd67
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Re: Oil pressure

Post by dpcd67 » Tue Jun 30, 2020 7:10 am

Get a Melling.
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Joe Gopan
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Re: Oil pressure

Post by Joe Gopan » Tue Jun 30, 2020 8:14 am

OEM Pump on M-38 Engines was manufactured by EATON, There is a tendency by restorers to install original Eaton's no matter how worn to retain the OEM appearance. The Melling has been the most common aftermarket since the 50's. Do your engine a favor and install the Melling.
Early Eaton had an aluminum body, later Eatons used a Cast Iron Body. There s no difference in operating pressures between early or late EATON.
Some of the surplus dealers occasionally turn up a NOS early Eaton,but that is rare. :wink:
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
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Cannon Cocker
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Re: Oil pressure

Post by Cannon Cocker » Tue Jun 30, 2020 3:02 pm

What melling model do you recommend?

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Re: Oil pressure

Post by Joe Gopan » Tue Jun 30, 2020 3:08 pm

For the 134 CID 4/CYL, specify chain or gear Drive. I do not have my Aftermarket manuals handy. Will look on my shelf to see if the Melling Number is on the new pumps I have.
Might not get it tonite.
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

Cannon Cocker
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Re: Oil pressure

Post by Cannon Cocker » Tue Jun 30, 2020 3:25 pm

Gear driven. Thanks

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