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m38a1 transfer vent line routing ?
Posted: Sat Sep 24, 2016 11:34 pm
by Saberr
About to drop my re-built engine into chassis, and was hooking up the vent and oil lines today. I was stupid and didn't get good pics before i took engine out. Have checked through all the info i can find and tm-9-8015. I can not find where the transfer case vent line ends. I know it runs from T on top transmission up and along the block. That was all. The none handled pumps it ran to front of, but what about on the handled pumps ? Only place i can think of is the T before the pvc valve and after pump. Can't figure out if something else hooks in that T. When i got the jeep, all lines existed, but were not connected since a single action pump was installed, the lines that were there just hung.
Posted: Sun Sep 25, 2016 1:54 am
by wesk
Posted: Sun Sep 25, 2016 9:53 am
by Saberr
Looked through your album wes, ether im blind or its just going right over my head. Only picture was once again fg 110 engine vent system. Cant tell if the vent line goes in the T fitting or not, just too general of drawing and the fuel pump is pulled away in drawing. I didn't see any real pictures with the lines ran with the handled pumps ether.
Posted: Sun Sep 25, 2016 10:06 am
by OKCM38CDN
Transmission vent line; if equipped went from the Transfer case to the Bell Housing (Tee used here) then over along the engine to the Fuel/Vacuum pump to a one way ball check valve. This is the same as on the M-38...
Hope that helps...
Posted: Sun Sep 25, 2016 10:26 am
by Saberr
ok, the check valve is a missing piece of the puzzle. Now, how does that connect to the pump ? Where is this connection ?

Posted: Sun Sep 25, 2016 1:13 pm
by 4x4M38
It's right in front of you! But it's not!
The photo you posted shows an "axle " vent fitting screwed into the port
where your line goes. It's actually holding the priming handle on.
Where the vent system was removed or not installed they put that vent
fitting in there.
Go look at the M38 fording ventilation information. You are looking for the
late version.
Take care,
Posted: Sun Sep 25, 2016 1:26 pm
by 4x4M38
Here's the link:
http://willysmjeeps.com/downloads/cjv35u.pdf
Go to the M38 section page 2.
Once you see it you can go back to Wes' pages and see it was there all along!
That vent fitting threw you.
Posted: Mon Sep 26, 2016 12:14 am
by wesk
Looked through your album wes, ether im blind or its just going right over my head. Only picture was once again fg 110 engine vent system.
You are definately not seeing very well.
Here's how to access the correct album:
1: Click on my main album:
http://www.willysmjeeps.com/v2/modules. ... _album.php
2: Click on my M38A1/M170 Fuel System Album:
http://www.willysmjeeps.com/v2/modules. ... _album.php
3: On page 2 of my M38A1/M170 Fuel System Album, Click on Vent & Fording System Album.
Tyhe M38 system has many similarities but it may just confuse your issues.
Vented Cap
Posted: Wed Mar 24, 2021 8:37 am
by ocwd
I would like to install a vented cap on my fuel pump. The vented cap is shown in Wes's illustration above. Just a couple of questions.
1. Where to buy such a cap?
2. What is the thread size and pitch?
Thank you,
Dave[/list]
Posted: Wed Mar 24, 2021 8:53 am
by wesk
Search our posts here. There was a member in Canada selling new ones.
Posted: Wed Mar 24, 2021 10:56 am
by RonD2
I could be mistaken, but thought it was the same vent used on the differential covers?
If yes, MWM has them for $6 each here:
https://store.midwestmilitary.com/product-p/915564.htm
Posted: Wed Mar 24, 2021 10:30 pm
by wesk
Yes. Both are found easily in your copy of the M38A1 ORD 9 SNL G-758!
Valve, fuel pump air vent, Used after sn MD23359 ORD# 5196397 Pg 83
Valve, axle vent ORD# 5196397 Pg 219
Vented Cap
Posted: Thu Mar 25, 2021 7:36 am
by ocwd
Thank you. Same part number so threads should match. I'll order from John. Once upon a time I hade one of these axle vent caps in my parts but I lost track of it. Oh well.
Posted: Thu Mar 25, 2021 10:14 am
by wesk
You can probably find one just as easily at your local auto parts store in their Dorman Racks!
Vented Cap
Posted: Thu Mar 25, 2021 6:48 pm
by ocwd
I’ll go check it out this weekend. Thanks for the tip.