AIr system leak, Rear gladhand this time

[expeditionnw]

1997 M1078.

When the park brake release valve is pushed, the air continues to exhaust from the rear emergency gladhand.

I have pulled the three valves apart behind the washer bottle, all three were good. The truck recently went thru a rebuild, so this wasnt surprising.

I have looked thru the TMs , I didnt see anything that would cause this. Id rather not open up the rest of the valve for no reason at this point.

I know I am missing something her, anyone else ran into this?

 

[NDT]

The (yellow) edit: red valve supplies air to trailer connections, it's not on is it?

 

[expeditionnw]

The yellow valve supplies air to trailer connections, it's not on is it?

The yellow valve is the park valve. the red valve is the trailer valve, but no, it is not on. I wonder if someone had the valve out and put it back in wrong.. I hope not, those things suck to do.

 

[expeditionnw]

Is the trailer park valve the only stop in the park release air?

In other words, if I had the exhaust line pulled off the trailer valve, When I release the park valve, no air should be leaving the trailer valve dump? Or is there something else down stream? This really seems like a dumb question.

 

[expeditionnw]

I pulled out the tractor protection valve and disassembled. Like the others, everything was clean amd new, seals plyable.

It appears that the rear emergency gladhand just passes thru there? I didnt see any fuction of that valve relative to the gladhand circuit.


any insight fellas?

 

[Suprman]

I believe the tractor protection valve should prevent air from free venting from the rear gladhands. I have seen rear anti compounding valves stick. The tm does have a flow chart for that. If is a new problem the tm troubleshooting should work. Whenever I get a truck it it's usually 2 lines swapped somewhere and the flow chart has me going in circles.

 

[expeditionnw]

Thanks Will, this is a new truck. Suspecting something is hooked up wrong.

I introduced a small amount of marvel mystery oil to the air system thru one of the hand valve connections, cycled stuff for awhile and accomplished nothing but a nice mess.

With the park valve released (air dumping freely from the rear E port), i sat under the truck and cycled a cap over the Leaking gladhand. With the line capped, the rear cans fully released, and with it open, the cans tightened up. To me that means the leak is before it hits the brakes.

i also noticed, with full air, park brake released, I can release the trailer valve and it doesnt exhaust- as if i had a trailer back there. Normally the valve would bypass and blow off right?

 

[Suprman]

The tractor valve prevents air dumping. I have never stood back there while someone pushed the trailer control. Before you go crazy you should check the 3 valves under the drivers foot area. I had a truck that had all 3 bad, bad treadle valve and a bad tractor valve. Wouldn't build air at all. Would just dump out one of the vents over the rear wheels. You can just take the front half of the valve off to check them. Don't have to unbolt the entire valve.

 

[expeditionnw]

Well I found the issue. After going thru every valve on the truck and finding nothing, I should have stuck to my gut. Some clown had the dash valves hooked up wrong.

system works great now!

 

[rosco]

Sounds like a "quick-release" valve sticking open or closed. When brakes are applied (any brakes - service or parking), the air must be dumped rapidly, to release them. Back track that glad hand line, till you find it.

 

[Reworked LMTV]

The tractor valve prevents air dumping. I have never stood back there while someone pushed the trailer control. Before you go crazy you should check the 3 valves under the drivers foot area. I had a truck that had all 3 bad, bad treadle valve and a bad tractor valve. Wouldn't build air at all. Would just dump out one of the vents over the rear wheels. You can just take the front half of the valve off to check them. Don't have to unbolt the entire valve.

Can the tractor valve be rebuilt? Do we have a number for this unit. I have been looking through all the TM's, but did not find much.

 

[Suprman]

Yup. Usually cracked diaphragms. The haldex rebuild kit is around 30 bucks. I can't remember the number it's posted somewhere.

 

[Andyrv6av8r]

http://www.ryderfleetproducts.com/ha...e-p-u55-rn31bc

 

[coachgeo]

for future reference; for future readers... there is a sticky on top of this forum that you can use to see a list (spreadsheet) of part #'s. Folk can recommend Parts and # to the originator of the list via PM

 

[Reworked LMTV]

Yup. Usually cracked diaphragms. The haldex rebuild kit is around 30 bucks. I can't remember the number it's posted somewhere.

You are always a great asset to SS. Thanks Suprman!

 

[Reworked LMTV]

for future reference; for future readers... there is a sticky on top of this forum that you can use to see a list (spreadsheet) of part #'s. Folk can recommend Parts and # to the originator of the list via PM

I went there first. The part is listed as the "air protection valve" not, tractor protection valve.

 

[coachgeo]

I went there first. The part is listed as the "air protection valve" not, tractor protection valve.

PM the OP to suggest adding "tractor protection valve" into the wording. he's a good fellow

 

[jpinst]

Make sure you don't seal off the glad-hands too tightly, they are supposed to leak a little bit. If they are completely sealed, your brakes will lock up and you are not going anywhere. Learned that the hard way and from one of those comic book style maintenance bulletins...

 

[expeditionnw]

Make sure you don't seal off the glad-hands too tightly, they are supposed to leak a little bit. If they are completely sealed, your brakes will lock up and you are not going anywhere. Learned that the hard way and from one of those comic book style maintenance bulletins...

True, sort-of. Depends which gladhands you are sealing, and what the issue is to begin with.