M939 transfer case air lines installed wrong

[Scott88M]

I don't think I could've gotten that washer to budge. I did want to be able to easily switch it back should the need ever arise. 2 mins with a flathead and it's lined back up.

 

[plode]

I took the washer off too. It was actually pretty easy to get it off the linkage shaft.

 

[cobratodd]

Where can I buy a new air valve? It appears as though my M923a2 valve is gray plastic, it is split, and is leaning air. (Or am I confused and not looking at the right part?). I tried searching the net but I must not be using the correct terminalogy for that part.

 

[jwesley74]

I'm going to go out and do this today...as soon as the ground under the truck dries. I power washed the bed about an hour ago. Will post back if it works. I'm sure she'll be happy to get that front axle unlocked.

We did ours on wednesday. Easier than anything, just used a 3/8" DOT line quick connect fitting to splice the 2 together coming from the dash switch to the T-case and for now kinked the 3rd line to the auto switch. We'll get a quick connect DOT line cap for 3rd line and be done with it. Now full control at the dash switch ONLY.

 

[railroadmike]

Ok so I'm having the same trouble, and my lines are hooked up totally different than on page one, bleed the air and the high low lever moves easily running it won't budge, I just about drove 400 miles today, and need help, I have a 931a2 and the spare and rack are right on top of these valves, with out even a hand drawn map of how this is supposed to go I'm a bit lost as for what A B or C is on my truck as I have two inches to see the top of the t case, HELP!!!!

 

[railroadmike]

GOT IT! thanks to the info here and studying the diagrams in the TM, I disconnected the air jumper from the tee on the frame to the selector valve as mentioned in this post, and left only the cab valve line attached and poof... All good, the lock out button on the hi lo lever is still a bit temperamental, but i can now roll the 400 miles home and not harm the truck.

 

[MuleMac01]

I mean how do you know your front axle is engaed when driving down the road and not looking at the air lines?? would it make a noise when turning all the wheel all the way to 1 side??...

 

[railroadmike]

I started getting suspicious when doing three point turns, I could feel some binding so I checked. With every thing in regular drive and no dash indicator truck in neutral rolled to a stop set park brake, reached under the truck grabbed the front shaft and it wouldnt budge, once i shut the truck down and bled the air it did. Another thing was I could not move the high/low t case lever with air pressure in the truck, now it does, and the front shaft wiggles like it should in park.

 

[Capn Hook]

I have the M936 Wrecker. What with the wrecker body on it, the only access to anything down there is from underneath with a flashlight. My truck was overhauled at RRAD, and will not shift the transfer case with any air pressure. Also I think my front axle is locked in. Where is the Air Protection Valve located? I see replumbing the air valve to the front end for dash control only, but I cant really get to the transfer shift lines very easily, and they appear to be different size lines, so simply switching them doesnt look like it will work. Perhaps if I could find that Air P.. Valve, I could switch lines there?

This looks like maybe we might have to do heart surgery on this beast through the rectum. This is my first post on this site,,,and fellas,, I am sure feeling blessed to have found it.

 

[Vintage iron]

I work on these trucks for a living. I would say 50% of the trucks that I have seen have the tranfer case plumbed wrong.

 

[VPed]

For disabling the auto-front lock on mine, I just took the linkage with the washer on it and reversed it. Pull the two cotter pins, the two clevis pins, remove the link and reinstall with the washer towards the front, insert the clevis pins, and replace the cotter pins. Consider using hairpin clips if you want to easily reverse the procedure.

 

[Alexsha]

I have the M936 Wrecker. What with the wrecker body on it, the only access to anything down there is from underneath with a flashlight. My truck was overhauled at RRAD, and will not shift the transfer case with any air pressure. Also I think my front axle is locked in. Where is the Air Protection Valve located? I see replumbing the air valve to the front end for dash control only, but I cant really get to the transfer shift lines very easily, and they appear to be different size lines, so simply switching them doesnt look like it will work. Perhaps if I could find that Air P.. Valve, I could switch lines there?

This looks like maybe we might have to do heart surgery on this beast through the rectum. This is my first post on this site,,,and fellas,, I am sure feeling blessed to have found it.

1st step would be to jack up the front end and check the axle lock function. Air up the truck, jack up 1 side of the front and see if the wheel spins with the axle lock off. Then set the lock and see if the wheel stops. If that functions correctly then move on to diagnosing the transfer case.

 

[Rockafellar Deuce]

So I have a M929A1 that just started leaking gear oil out of the "front axle lock in valve" directly onto my left foot today. I'm guessing there must be a plugged vent line somewhere. Anyone have an idea where I should start looking.

 

[railroadmike]

Woa, thats a strange one, it's an air line, are you sure it's not oil from the compressor? Or is it bleeding from the non pressure side coming from the t case?

So I have a M929A1 that just started leaking gear oil out of the "front axle lock in valve" directly onto my left foot today. I'm guessing there must be a plugged vent line somewhere. Anyone have an idea where I should start looking.

 

[Rockafellar Deuce]

Oil smells a lot like gear lube. What type of oil is in the compressor? Though there was no oil in air tanks when i drained them down. I would think there would be oil there if the compressor was leaking oil. Haven't had time to look into it anymore since I got the truck home. Probably won't until the weekend.

Woa, thats a strange one, it's an air line, are you sure it's not oil from the compressor? Or is it bleeding from the non pressure side coming from the t case?

 

[tashaak]

You say you work on these for a living, cool. I have a recent problem since it turned cold. I cannot lock in the front drive it just keeps hissing air what sounds like it is coming from the stack where the vent lines go. The green light will not come on. I get it up to full pressure but it will not lock in. Is it a temperature issue. I never had a problem before when it was warmer. This is my first winter with the truck. I have an air dryer also. Is it common for this to happen. Thanks

 

[Suprman]

Possibly moisture frozen in an air line. Have you ever serviced your air dryer? How old is the cartridge? Do you drain your tanks every time you use the truck? The air dryer helps but doesn't do a superb job of cleaning the air. Especially when you are in a cold climate moisture wreaks havoc in your air system. I have been installing updated model air dryers in my trucks.

 

[tashaak]

The Haldex air dryer cartridge is about a year and a half old. No I do not drain the lines after use,I should probably make it a habit to do so. The updated dryers ,how much better are they? What about a alcohol evaporator. I will be moving back to Alaska in a couple weeks so I do need a better way of keeping out moisture. What is the better way to go,with the updated dryer or evaporator. I will of course drain after use from now on.

 

[Suprman]

You need to drain the tanks every time. That's the number one way to keep the system moisture free. The updated air dryer helps a lot. You can put some alcohol in your system to get all that built up moisture out. It will take a long time if you have ctis and the tires have a lot of moisture in them.

 

[tashaak]

Can you give me the name and model number of the updated dryer you are talking about. Where can I put in the alcohol or air brake antifreeze ,which is better. And how much do I put in.