Leaky Dash Tractor valve?

I had mine hissing all the time,,,come to find out it was the trailer line... I tore my dash all apart... air brakes were leaking on the trailer... duh?

Mark

 

That hissing noise is known as an "audible air leak" and while it may be coming from the valve itself it could also be the sound of an air leak from another part of the system. Rule that out before replacing the valve.

I find if the valve is leaky, giving it a slight twist stops it pretty quick too.

Last one I had replaced the mechanic put the news in backwards. Red on the left, yellow on the right. I tried it for two weeks like that but then back to the mechanic to fix his eff up.

 

long ago I heard a large leak in the dash behind my dash valve. replaced valve. still had the leak???? it was an air bag leaking so bad that you heard the air going to bag, trying to replace air lost. the sound was right there at the dash valve, but the leak was not. soap & seeing air bubbles is where the leak will actually be. & yes the unit is sold as a whole. both valves.

 

Bendix has an oring/seal kit to service that dash valve for cheap. No need to remove the valve from the truck when servicing as all work is done from the front of the valve. I've done many and it worked every time. Kit comes with instructions.

 

You do not have to change the whole valve. Pumop all the air out of the system then take the small screws out of the face plate. Pull the vlave out(this may be a hard pull) take some petrolium jelly and lube it up then reassemble. It will stop that leak about 60% of the time. Also you may have a leak in a break can that is feeding back thru the dash valve. Don't want to see you spend money on something that won't fix the problem.

 

Let us know if that fixed it. It won't hurt so bad if it does.

 

Most of the time your hearing air passing through the valve to another leak. A small leak else were in the truck is most likely your culprit. Check all your break chambers as I found they are usually the problem when you hear that hissing at the valve. It could however be almost any thing on the primary side of the air system. Build your air up and release your tractor breaks. Turn off the truck and listen. It might be a small leak so listen carefully. Yes it could be the valve it self but not usually.

 

Agreed, had a driver insist the valve in the dash was leaking. Ended up being a brake chamber.

For future reference here's a link for the rebuild kits (spool kits). Not sure if the prices are good but the part numbers help at least.

 

His valve should be a bendix MV-3 which would use the bendix 107216 maintenance kit, cost $19. The MV-2 was used on earlier trucks and is the first combined module version.