Has the forum been a little slow as of late....or is it just me? Oh well..........I need some help with my cock. Hmmmm.........that didn't sound right....what I mean is I need some help with my M37's cock.
In both ORD 9 and TM 9-2320-212-20P it shows there should be a cock at the gas tank for the filler tube vent line. My M didn't have a fuel tank when I bought it, but I did end up buying two tanks over the past year (one useable, one a piece of carp) and neither has the cock shown in the manuals. They just have a metal vent tube with a flare fitting coming out of the tank and a plain metal tube end on the other end that the rubber hose attaches to that connects to the vent line on filler tube. I've also taken pics of M37 tanks when I go to Rallys on other people's truck and I don't see the cock in any of my pics.
So am I the only one missing my cock? If you've got one on yours can you post a pic of it so I can better see what I'm missing? (Keep it clean guys, this is a family friendly website!!)
I thought I read in one of the manuals (probably an early one) that as part of preparation for fording the cock on the filler vent needed to be closed......or water could get in the gas tank. I can't find that specific manual right now......but I'll look harder later. If there is no cock on the vent tube then how did they keep water from going in the tank vent?
bob way I see it is gas tank vent vents to the filler neck with a short piece of rubber line, when you ford you tighten the gas cap down to its 2nd click to close off air to the filler neck. then the crankcase vent line that runs back to the tank provides ventilation for the gas tank.
My guess is the illustrator mislead the technical writer in his drawing the shut-off too close the the vent tube and wrote the description incorrectly, as it's actually the fuel tank drain COCK.
The early trucks were obsessed with the ability to ford. One of the things changed early on was THAT valve, as they went to gas caps with a selector in them for vented or non-vented.
That took care of the problem and no more use of THAT valve.
Thanks for the info. I have to say I didn't know the gas cap had two positions...or clicks. I'm going to try that when I get home. Makes sense about why they removed the cock early on too. When I read the TM regarding forging it didn't say anything about closing the cock or tightening the gas cap....but I'll go read that part again tonight.
OK, a question. For those who think the valve goes in the vent line, Why?
The only way water can get into the vent line is through the fuel filler neck/cap. And if it gets in there it's going into the tank through the filler pipe regardless of any vent line valve.
You're right....the only reason I asked is because I see the cock listed in (2) M37 manuals and it's identified as "cock, shut off, filler pipe vent tube". And the part number given is the same as the cock by in the inlet to the fuel pump.....so it's a valid part number. So it's not called the fuel tank drain cock, or anything else....it's called out as part of the tank filler tube assembly. So either it was used on early trucks only, or at least (2) manuals are wrong. Just trying to figure out which.
My guess is still that the illustrator mislead the technical writer in his drawing the shut-off too close the the vent tube and wrote the description incorrectly.
You certainly could be right. Just seems a bit odd that the manuals I'm talking about are dated 1954 and 1960 and in all that time no one ever caught that error and fixed it. I know where there's an early '51 M rotting in the woods....when I get some time (and the mud dries up) I'll pop over there and see if it has a cock on the vent tube.
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