M38 CDN Underwater Venting

Lyle · Post by **Lyle** » Tue Dec 18, 2018 8:30 pm

There are two special brass fittings within the venting system; one is a brass metering connector, 7348568, WO-802665; the second is a brass ball check connector, 7375063, WO-800347.

Two questions:

1) Does anyone know where I can source these?

2) Does anyone know the spring pressure of the ball check? 5psi, 10 psi, ... etc.

OKCM38CDN · Post by **OKCM38CDN** » Tue Dec 18, 2018 9:44 pm

The Ball Check valve was available, there was a posting by a gent from Canada that had purchased a small amount of these and was selling them to members of the group. You will have to research the posts to find it. I had the info, but have misplaced it. The Ball check valve can be replaced / substituted by using a 1/8" pipe to 37 degree inverted flair fitting; using the inverted flair nut on the end. This one is generally filled with solder to prevent air movement in the system - I have this setup on my jeep as the ball valve innards came loose and the spring / Ball assemblies are in my vacuum pump.

I searched the FOR SALE ads and found this posting:

http://willysmjeeps.com/v2/modules.php? ... ball+valve

I used the info Remi had and there was a company still making these, but would not sell to anyone outside Canada... that is why he had several he was from Canada and could get them at the time...

Hope this helps...

Lyle · Post by **Lyle** » Tue Dec 18, 2018 11:19 pm

Thanks for the info.... I think I'm on the trail of a manufacturer of brass fittings that looks like they have them.

Cheers, Lyle

OKCM38CDN · Post by **OKCM38CDN** » Wed Dec 19, 2018 7:35 am

Lyle if you find them and can get them, please post where and if they will sell below the border. I will admit I have one unused one but am saving it for use in my M-38 CDN here in Oklahoma... would like to have some spares... also Have an M-38A1 that may need one.

Lyle · Post by **Lyle** » Fri Dec 21, 2018 2:21 pm

Hal, you bet ..... I have found a supplier but need to determine the PSI of the original (e.g.: 1 PSI, 5 PSI, 10 PSI...etc.).

Anyone???

OKCM38CDN · Post by **OKCM38CDN** » Fri Dec 21, 2018 3:37 pm

If you look at the post earlier the one with the URL in it; it says 10 PSI

Lyle · Post by **Lyle** » Fri Dec 21, 2018 6:01 pm

Oops, I saw that as I was hitting the Return.

Wow, 10 PSI, I'm not too sure that it would be that high.

Well, I'll go with that until otherwise told a difference.

WillysMotors · Post by **WillysMotors** » Sat Dec 22, 2018 5:53 pm

Weatherhead 101-22803

Post by **wesk** » Sat Dec 22, 2018 8:54 pm

Lyle, Read your M38 engine TM 9-1804A pages 109 thru 113. Crankcase pressure will usually not exceed 2 PSI by more than a couple of pounds during fording operations with the fording valves closed.

OKCM38CDN · Post by **OKCM38CDN** » Thu Dec 27, 2018 3:30 pm

Anyone installing this valve, I have a suggestion. Dimple the ball end of the valve where the threads are to prevent the valve from coming apart in the Pump end...

With the vibrations and such the valve in my M-38 CDN came apart. the parts are more than likely in the vaccume pump as I have never taken it apart.

Just a suggestion to prevent this from happening to you...

Lyle · Post by **Lyle** » Fri Jan 04, 2019 6:43 pm

Thanks, Wes.... This is why I was concerned when the idea of 10 psi came up.

Please note that my Fuel Pump does not have the connection in mid-line of carb. So I'm trying to where else I can connect the vent tube from Bell housing.

it's not scientific but a scientific wild ass guess (SWAG)

I'm looking at 5 psi. I figure the Outlet of the Vacuum pump will pressurize the Bellhousing, Transmission and Trasfercase to a MAX of 5 psi (when Fording) with excess pressure "cracking" the ball valve at <5 psi and dump it into the intake manifold.

Post by **wesk** » Sat Jan 05, 2019 1:16 am

I would not use the pressure side of the vacuum pump. The pressure side of the diaphragms are not suppose to be loaded. If you load them with 5 or 6 PSI then they will fall short on the vacuum suction. You have two choices for the tranny/tranfer fording vent line.

1 - Connect it to the dipstick tube.

2 - Drill and tap a threaded hole in the center of your fuel pump and install the original style fittings. This way you are using only the captive crankcase pressure for the tranny/transfer vent tube. This is why the original pump has that threaded hole. The crankcase is vented right thru the center of the pump body where the pump internal lever is mounted.

Lyle · Post by **Lyle** » Fri Jan 11, 2019 11:14 am

I found the check valve. It has a Cracking Pressure of 2 PSI and Viton seals which give it a max temp of 450*F.

eBay.com:

MAINLAND VALVE & FITTING, INC.

1/4" MALE x FEMALE NPT THREAD
BRASS BODY
BRASS BALL
304S/S SPRING
VITON O'RINGS
SPRING LOADED 2 psi CRACKING
3000 PSI RATING
FLOW DIRECTION: FROM FEMALE SIDE TO MALE SIDE

SHIPPING WEIGHT: 6 OUNCES
(These products are represented as FACTORY NEW)
https://rover.ebay.com/rover/0/0/0?mpre ... 1610580992

Cheers, Lyle

Post by **wesk** » Fri Jan 11, 2019 1:50 pm

Lyle,

Your discovery can be made to work but will require significant adaptation. I would suggest finding the Weatherhead already mentioned above.

Biggest issue is Pipe thread size difference and the free flow direction.