Posted: Wed Jun 24, 2020 12:42 pm Post subject: M38 fuel/vacuum pump
Hello. I am having problems with the fuel system on my 1952 M38. I need some wisdom as I am not too familiar with the Fuel and Vacuum pump. I just took off the fuel pump and there is oil inside the vacuum part when I took the bottom cover out. Is that ok? _________________ RJ Ruiz
Thank you for the info. I read it but what I have is not oil on the top part of the pump (fuel pump). what i have is oil inside the vacuum part of the pump, the bottom where it looks like a cone. I am not sure if this is normal. _________________ RJ Ruiz
Wes, 90% of the lines are connected. Only two are missing and are the two lines that connect to the distributor, since the system was converted to 12v. Also, the vent line that connects to the center of the fuel pump, the one coming from the transmission/transfer case, is plugged, as I saw on a post here, since I could not find the ball check valve.
P.S. I'll be installing the original distributor as I found a 12v ignition coil that fits inside like the original 24v. _________________ RJ Ruiz
There, you hit the nail on it's head! The center vent on the fuel pump if plugged will cause the suction half of the pump to suck on the oil sump of the engine. You must vent that port to the atmosphere.
The vent fitting will alleviate the oil in the vacuum side of the pump problem.
The military distributor is designed as a sealed unit to allow fording operations. The two vent lines are critical to the well being of your military distributor.
Their real purpose is to vent out ionic gases from the distributor to prevent an explosion inside the distributor. In very hot climates they extend the life of your coil by keeping it cool and the venting keeps moisture from collecting in the distributor. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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