813 transmission

[groundog]

my transmission has 3 openings at right top side---2 tubes go to the transfer declutch---the third opening is missing the tube---what connects to this opening---checked -20 figure 149 but no help I know one comes in from the back side just below these also --- anyone familiar with the plumbing thanks

 

[Steamynachos]

Mine also has a tube missing on the middle one maybe it's suppose to be like that????

 

[groundog]

you are right---it is the middle one----but air comes out of it after I start to build air pressure---do you have a plug in yours?

 

[Steamynachos]

When I put it in reverse air comes out of it that seems to be the only time I can tell I cant get my head down near it while driving it is threaded like the others I think it might be for the deep water fording kit to thread into to vent the trans. but that is just a guess. There is no plug in it it's just open.

 

[groundog]

thanks for the info---I might have another problem---my master cylinder is leaking ---ordered a new one----maybe thats tied in some how---just bought the truck at auction---trying to check things out

 

[TheBuggyman]

My M813 has a fording kit on it, I'll try to remember to check when I'm out at the property this week.

 

[m139h2otruck]

The valve manifold on the side of the 5 ton shifter actually has 4 connections, air from main system in, two air control lines to the transfer case out and a 4th that is the dump port (open) when the system shifts, the hisssss when you go from forward to reverse. On our two trucks this port is just open, but for the fording kits, this may be connected to a vent system, not sure. Just make sure the valves and the shift cylinder are working correctly, if not, the transfer case could go BANG!!

 

[groundog]

when I go to reverse I get the hisssss sound but when I go to first or neutral I get constant air bleed from the middle port---possibly a valve stuck? help---not that familiar with system---also should I get a hisss sound when I step on the brakes?

 

[m139h2otruck]

I would say you have a bad valve or very loose/broken hose. I would not drive the truck until it is fixed or you risk a transfer case problem.

 

[BKubu]

DO NOT put a plug in the open line. You WILL pressurize the transmission. Been there...done that. I replaced that valve on my first M813A1. When I got the truck, there was a plug in that line so, when I took it apart, I put it back together the same way. Thankfully, Jeff S. (Tactical Truck) looked it over and immediately diagnosed the problem (the plug). I am not sure why the military put that plug in, but I was told that it is wrong.

 

[rdixiemiller]

That shouild be the exhaust for the air cyl. If you plug it, the cyl. can't move back and forth as the air is switched. This is a common feature on most industrial air actuators. If you have a constant air bleed, you could have a bad valve or a bad cylinder packing. Either one should be an easy fix.