M939A2 Leaking transfer case interlock cylinder

[FIREFIGHTER]

We have an M939A2 that is set up as a wildland/brush fire truck. The boys had the truck out this past weekend and one guy said he wasn't able to build air pressure and another guy who heard 2nd hand the truck would build air but after they shut it off is was leaking out of the air intake and pissing oil on the floor of the cab.............heavy sigh.
I finally made it down to the station today. The venting air coming out of the intake was coming from the transfer case vent and the oil on the cab floor was gear oil coming from the vent port on the front wheel axle lock in valve. So I am leaning very heavily on believing the transfer case interlock cylinder is leaking into the transfer case. And, somehow; the front axle wheel drive air cylinder is also leaking allowing the pressurized air in the transfer case to bleed back to the dash valve taking gear oil with it. Just not sure why the vent isn't relieving the leaking air into the transfer case.
So.......any thoughts or do you think I'm missing anything in my chain of logic??

-Do they make a rebuild kit for those cylinder?? Or are the internal seals readily sourced from outside vendors?? I haven't taken the air cylinders out of the transmission yet. I'm going to order some new/surplus ones first.
-Is there a comprehensive schematic/diagram showing the flow for the air system somewhere in the TM's?? I haven't found one, or for that matter; anything showing a flow diagram. Just some pictures of components and descriptions in the theory of operation for different systems.

Thanks for the help!!

 

[simp5782]

Download the p2p program at the bottom of the 5 ton TM section. It has the diagrams.

Bypass the solenoid. You do not need it. It generally just causes headaches. It is only there so the shift lever can't be kicked out on accident. It usually leaks air causing the gear oil in the floorboard or it will pressurize the transfer case itself and make it start leaking.

This video will show you how to do a single line air setup on the transfer case


https://youtu.be/6vfG2pVDOIU

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[FIREFIGHTER]

Thanks Simp.............I had seen the P2P listed before. I just didn't have the patience at the time to argue with it and get it going. Just got it working after trying for a bit. That really is a great program.

If I was the only one driving the truck, then I wouldn't hesitate to remove those safeties and streamline the air system.

So you take a guy who has never run heavy equipment, driven a heavy truck, doesn't have a CDL and drives a car or 1/2 ton pickup. Take him out and have him 'checked' out by another guy who drives a jeep wrangler (thats never seen off road). Now put him in a 65k lbs truck and have him drive it like he stole it to a fire. Yes, we DO NOT NEED TO HAVE A CDL HERE IN NH TO DRIVE A FIRE TRUCK. Kinda like the RV's that are out there.......no CDL required, but they are not driving it like they stole it.

It can get a little scary sometimes. I want/need all the safeties on the trucks I can get. Maybe it will keep someone from doing something stup

I ordered new cylinders off Ebay.

 

[simp5782]

Thanks Simp.............I had seen the P2P listed before. I just didn't have the patience at the time to argue with it and get it going. Just got it working after trying for a bit. That really is a great program.

If I was the only one driving the truck, then I wouldn't hesitate to remove those safeties and streamline the air system.

So you take a guy who has never run heavy equipment, driven a heavy truck, doesn't have a CDL and drives a car or 1/2 ton pickup. Take him out and have him 'checked' out by another guy who drives a jeep wrangler (thats never seen off road). Now put him in a 65k lbs truck and have him drive it like he stole it to a fire. Yes, we DO NOT NEED TO HAVE A CDL HERE IN NH TO DRIVE A FIRE TRUCK. Kinda like the RV's that are out there.......no CDL required, but they are not driving it like they stole it.

It can get a little scary sometimes. I want/need all the safeties on the trucks I can get. Maybe it will keep someone from doing something stup

I ordered new cylinders off Ebay.

You can disable the low range so he can't destroy the transfer case by putting it in low range. The air line mod just lets the dash valve control the 6x6 engagement and not some random cylinder. Be sure to remove the frame ground for that cylinder and clean it then attach the ground.

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