Need advice : Vent lines for the Air Cleaner on M38

[Randybee1]

Hey guys, New Jeep owner as of last week. An M38. I'm trying to fix some "loose ends" and need some help. So....

1. My Air Cleaner just has 2 holes in it ( nothing going into it). I put a nipple on one hole and attached the Windshield wiper line to it. I have no vent line coming from the gas tank but plan to run one to the air cleaner. Does that start out as a hard line and then goes to a rubber line? Or is it a hard line all the way to the air cleaner? Also, I have no vent line from my master cylinder so I assume I have an after market ( it also has the large 15/16 inch nut). Should I have a vent line for it? Right now I plan to just have a line from the windshield wipers and one from the gas tank go to the air cleaner. Does this make sense? Also, I do not see a vent line for the transfer case neither.

Thanks for any help.

Randy B

ps... more questions to come....

[LarrBeard]

RandyBee:

Welcome to the forum.

Your M38 had a fairly complex fording system of lines and vents that went to the gas tank, brake cylinder, differential, probably the ignition coil. the air cleaner and probably several other places I've missed. It was controlled by a fording valve.

I would suggest that you get a copy of the M38 tech manual to see the whole layout of the fording system. (is it an M38A1?)

Here is a link that describes the M38 fording system in detail.

https://cj3a.info/sibling/m38vent/vent.htm

And keep the questions coming!

[bmorgil]

Welcome RandyBee!

LarrBeard has you on the right track. Here is a link to the Tech section of this forum for the Engine/Clutch Military manuals on your M38. I think Chapter 6 briefly discusses the Fording System.

https://willysjeepforum.kaiserwillys...lity-Truck-M38

There are 3 or 4 manuals in the Tech Section for your Jeep. Keep the questions coming! gmwillys and LarrBeard have helped a few through the Military versions.

[Randybee1]

Thanks Guys, I have all 5 manuals. I haven't seen a good description (yet) of the vacuum lines/vent lines. Still trying to digest all this new info. I find it a little odd that there is a vent line for the MC. Fording or no fording I don't understand why. Everyday cars/trucks do not have vented MC systems.
Randy

[bmorgil]

I think you will find the link LarrBeard posted is as good as you will find. The Master Cylinder is vented and could take on water if submerged.

[Randybee1]

bmorgil, you're right .... Thank you LarrBeard, very good info!!!

I still do not understand the theory behind venting the master cylinder. Its a sealed system anyway so why add a venting system to it?

[bmorgil]

The cap of the master cylinder is vented so as the volume of fluid decreases in the master cylinder as the pads/shoes activate, wear, and fluid temperature changes, changing the level in the reservoir, there is a vent to equalize the pressure.

[gmwillys]

Welcome Randybee1

I'm a little late to the party, but here is one of the best diagrams that I had in my archive of nearly worthless knowledge:

http://willysmjeeps.com/downloads/M3...stem.12.04.pdf

[Randybee1]

Thanks gmwillys! Excellent info.