1953 M38A1 PCV Question

lasmith03 · Post by **lasmith03** » Sun Apr 11, 2021 3:00 pm

A customer brought us this 1953 M38A1 that he had "restored" at another shop. It was leaking oil out of every possible orifice. Turns out it didn't have the proper PCV setup and the head surface was warped. We sent the head off and had it planed and then painted it etc.

Now the question is about the PCV. I haven't found much on what would be correct if you didn't have the fording system. This jeep does not have it and the customer does not want it.

So do I just need to run the PCV out the tappet cover (like what's seen in most pics) to the port on the intake manifold below the carb?

Also, someone made their own intake crossover tube which I want to replace with the correct stuff. What was correct if you didn't have the fording system? do you just buy the crossover tube and remove the fording valve in it?

Lastly, the ports on the air cleaner that are normally used for fording/venting...do I just need to plug them?

Any help is appreciated. Just learning about these. My first one.

Lance Smith
Rocket City Customs
Huntsville, AL

mdainsd · Post by **mdainsd** » Sun Apr 11, 2021 3:51 pm

welcome aboard! Familiarize yourself with the photo galleries and the download section. Especially Wes' photo album, a huge wealth of information. The manuals for your Jeep are in the downloads.

RonD2 · Post by **RonD2** » Sun Apr 11, 2021 6:38 pm

Hi Lance,
The PCV works like any other vintage car PCV, nothing special. Make sure wherever it's installed it's clean and pointed in the right direction ---- it's a valve, there's only one way in and one way out. The military vent system does nothing but shut off outside air in order to pressurize the crankcase about 2psi to keep water out. When those two fording valves aren't closed it's a regular vintage car PCV system.

Leave out or bypass the fording valves, but make a complete circuit so the PCV operates the same way it would on the 1965 Ford F100 in your shop. Simple. Point the PCV in the wrong direction and you'll have issues you've seen before.

Buy a correct M38A1 crossover tube for the customer (available at several military jeep vendors) and hook it up without the valves. Plug any fording vent lines not used on the air filter or anywhere else, with caution. Brake master cylinder needs a vent is one example. So does fuel tank.

As mentioned, the tech manuals are available for free on the downloads page here, and if you use the search button above and type in "PCV" you'll get plenty of hits to read. There's plenty of info about every nut and bolt on the M38A1.

Because you're in business making money doing this for a customer, after a while we're going to expect you to pay a consult fee to help keep this forum going.

Good luck!

RonD2 · Post by **RonD2** » Sun Apr 11, 2021 7:20 pm

And here's a nice NOS crossover tube for the M38A1.........

https://www.ebay.com/itm/Crossover-Tube ... SwuqNf42Wg

RonD2 · Post by **RonD2** » Mon Apr 12, 2021 8:23 am

This might also be helpful...….

https://cj3b.info/Tech/PCV.html

4x4M38 · Post by **4x4M38** » Mon Apr 12, 2021 1:55 pm

That’s a great site Ron.

RonD2 · Post by **RonD2** » Mon Apr 12, 2021 6:51 pm

Yeah, I thought so too Brian. Just trying to point out all the good info out there on this forum and others that can be had pretty easy just for looking.

Maybe Lance will come back and tell us if it helped him any. It was his first post. Might have scared him off by asking for a cut.

He does take pretty good photos, which not many can do.

STXM38A1 · Post by **STXM38A1** » Wed Apr 14, 2021 10:03 am

From Wes' Library

http://www.willysmjeeps.com/v2/modules. ... _photo.php[/img]

lasmith03 · Post by **lasmith03** » Fri Apr 16, 2021 6:02 pm

RonD2 wrote:Yeah, I thought so too Brian. Just trying to point out all the good info out there on this forum and others that can be had pretty easy just for looking.

Maybe Lance will come back and tell us if it helped him any. It was his first post. Might have scared him off by asking for a cut. He does take pretty good photos, which not many can do.

Hey guys. Thanks for the help. Yeah I had already seen alot of that stuff and did my research before hand. That PCV tech info was new though. Its just some of the details I wasn't sure about.

I bought that NOS crossover tube and a PCV from the guy on ebay. I also found a few preformed NOS PCV lines on there too. Thought they might possibly save us some time if the connections work.

This jeep doesn't have a vacuum fuel pump but I figure as long as I run that PCV to the intake port it should pull enough vacuum. Then its just a matter of connecting up the rest of the crossover tube connections correctly. Everyone agree?

Since we aren't going with a fording system I think all I should need in addition to the PCV to intake would be the valve cover to oil cap and then oil cap to crossover tube connections and plug the rest. No?

lasmith03 · Post by **lasmith03** » Fri Apr 16, 2021 6:05 pm

STXM38A1,
What would C and V in that drawing be?

Post by **wesk** » Fri Apr 16, 2021 8:34 pm

All you need to do is lay the two illustrations out side by side.

"C" would be "H" and "V" would be "K".

mdainsd · Post by **mdainsd** » Fri Apr 16, 2021 9:19 pm

Why was my post deleted?

Post by **wesk** » Fri Apr 16, 2021 9:27 pm

I have no idea.

mdainsd · Post by **mdainsd** » Fri Apr 16, 2021 9:43 pm

Weird. Thanks Wes.

STXM38A1 · Post by **STXM38A1** » Sat Apr 17, 2021 11:13 am

Top two items are the specs on your "C" and "V" or "H" and "K" in Wes' clear illustration.