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Working on my m38a1 - I don't plan to do any water fording and none of the ventilating system exists, and I will be using a single action fuel pump so no vacuum. Should I plug all of the places where pipes/tubes would connect or do they need to vent (main concerns are brake master cylinder, fuel tank, and some parts of the engine)? I don't want to leave them open and allow dirt/debris to enter, so if not plugged should they be covered with some kind of filter?

Always either post the jeep model or add it to your signature in your profile so we can all be on the same page.

Fuel tank, master cylinder and engine crankcase vents need to breath. If you are not going in the lake with the jeep then put an 1/8" pipe plug with a 1/64" hole drilled in it in the lid of the master cylinder. What to do with the fording valve plumbing depends on what model jeep you have. The tank needs a vent at the disconnected vent tube. The late M38A1 tank vent works fine there. I do not see the harm nor the difficulty in maintaining the vent tube from the gas tank to the air cleaner.

Thanks for your help - I'm still on the learning curve for getting what I need advice on. I think I have added my jeep model and year to my profile. There were no identification tags on the vehicle - from what I can tell it is an M38a1 Willys 1953 (at least mostly) - that's what CA DMV registered it as. I am trying to get it running well and safely for the Camp Delta meeting near Sacramento, CA this April. Almost done with replacing brakes, drums, flexible tubing, rusted steel brake lines, master cylinder. New fuel tank (upgraded from a plastic milk jug) and carb rebuild, new military tires and wheels.

Looks like I should just start installing the entire ventilation system - a bit of a challenge since I think it is all gone and have no model to work with. Should I just get a roll of steel brake line (what size) tubing and bag of fittings and flare the ends of the tubing - or will copper tubing be durable enough? Standard brass connectors in some places? I think I have seen some diagrams of the ventilation system and can look those up again. Since I have single action fuel pump how will that complicate the completion of the ventilation system?

I think I have added my jeep model and year to my profile.

No, you haven't or it would appear at the bottom of the dialog box in each of your posts.

Click on "Profile" near the top of the page. Then scroll down the profile page to the block right after the "Interests" block.

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Download the free PDF copies of our manuals from our download page and if you wish buy paper copies from Portrayal press. The basic manuals you need can be found at: http://www.willysmjeeps.com/v2/modules. ... oad&cid=63

These are free for you to download and please USE THEM. You will find 90% of the answers to your questions in them.

The tubing parts numbers, materials, sizes and lengths are in them.

Print some of the very clear illustrations from them that show all the plumbing for reference. No model needed. Decide how much of the vent system you want to use. Willys at the direction of the Army discontinued most of the underwater fording vent system after early 1953 at serial number MD23359. So you do not need a lot of plumbing nor do you need the fording valves. TM 9-8015-1 M38A1 engine manual has chapter 6 dedicated to the vent/fording/PCV system and has good illustrations.

The parts manual ORD 9 SNL G-758 lists the parts used or not used before and after MD23359. They are clearly marked.

wesk wrote:Always either post the jeep model or add it to your signature in your profile so we can all be on the same page.

Fuel tank, master cylinder and engine crankcase vents need to breath. If you are not going in the lake with the jeep then put an 1/8" pipe plug with a 1/64" hole drilled in it in the lid of the master cylinder. What to do with the fording valve plumbing depends on what model jeep you have. The tank needs a vent at the disconnected vent tube. The late M38A1 tank vent works fine there. I do not see the harm nor the difficulty in maintaining the vent tube from the gas tank to the air cleaner.

Wow, never knew about the hole in master cylinder plug,I thought it wasn't supposed to get air? Without the hole what happens? Mine is plugged with no hole, I'll have to change that. Thanks,Wes

The same thing happens to the brake fluid in the reservoir as does the gas in the gas tank when you don't vent it (let it suck air in) as the fluid level drops the fluid level will not be able to drop.