Joined: May 10, 2010 Posts: 615 Location: North Yorkshire, UK
Posted: Wed Feb 13, 2013 11:16 am Post subject: Check valve for M38 vent system & cold weather primer
I picked a couple of these up on Fleabay a few weeks ago:
While not an exact match, I believe they'll be a good substitute for the check valve that goes on the M38 fuel line up to the cold weather primer (and the vent line from the fuel pump to the bell housing on the "late" M38 engines).
The connections are 1/8" NPT female & 1/8" NPT male; due to the orientation of the valve, I'll need to use a couple of 1/8" NPT nipples & unions to connect in to my vent/primer system.
Note there's no spring inside this valve; it may be wise to fit one into the valve that connects to the fuel pump. The primer valve sits vertical, so should be fine without a spring. Here's the vendor details:
The check valve is inserted in the "T" labeled in blue.
It is shown as a "Connector" and is screwed into the 90 deg elbow coming out of the center of the fuel pump. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Towards the bottom of the page, it shows a special fitting coming out of the fuel pump (last photo but one). Note that the "early" M38 (pre-engine no. 74419, according to that website) does not have this set-up.
The second valve is for the cold weather primer. The fuel line that links the fuel pump to the tank has a shut-off valve, with a brass tee connected to the front of it. If you have the cold weather primer system installed, the valve goes in the top of this tee. It's item "V" on Page 64 of the M38 ORD 9. If you don't have the cold weather primer, then the tee gets plugged (i.e. no valve).
Not sure if the M38CDN had the vent system or the cold weather primer though. The Canadian parts & maintenance manuals should tell you.
Owen. _________________ Owen
1951 US Air Force M38
1944 F-1 1/2-ton Airdrome Trailer
1940 C15 Chevrolet CMP 11-cab
1939 DKW KS200 Motorcycle
MVT # 19406
That is not a cap in the sense of a closed plug. That is the same one way vent fitting (ORD # 5196397 or Spicer # 16979) that is used in the differentials. When the "Under water vent system" was removed that was used to keep the crankcase vent port of the pump open but still keep any trash out of the pump. In the case of the M38A1 after MD23359 in 1953 Willys discontinued the "Under water vent system" plumbing and that fitting was used instead. (it can be seen in fig 67 on page 155 of TM 9-8014.
Early M38's up through MC53262 (Feb 52) did not use that port on the pump and it came with a square head 1/8" pipe plug. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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