Air leak from brake exhaust

[Friday1]

Originally Posted by Robert & Dianne

Thank you Gardner
Do you know where the Spring Brake Valve is located? What you have written makes sense as my brakes do not hold completely when I give it fuel with brake set.

Are your rear brakes adjusted properly?

Rick in Ohio

[Rick]

Originally Posted by Robert & Dianne

Thank you Gardner
Do you know where the Spring Brake Valve is located? What you have written makes sense as my brakes do not hold completely when I give it fuel with brake set.

Have someone that knows how to adjust your brakes get ahold of them quick. The parking/emergency brakes are applied by a BIG spring not air pressure. Its the lack of air pressure that lets the spring do its job. If the brakes are not adjusted correctly the spring will not apply enough pressure and the parking/emergency brakes will not hold.

[mpierce]

Originally Posted by Rick

Have someone that knows how to adjust your brakes get ahold of them quick. The parking/emergency brakes are applied by a BIG spring not air pressure. Its the lack of air pressure that lets the spring do its job. If the brakes are not adjusted correctly the spring will not apply enough pressure and the parking/emergency brakes will not hold.

Almost always it means also that you are NOT getting full brake application when you apply the normal brakes to slow or stop.

On my Peterbilt, I only have spring parking brakes on one rear axle. Saves a little weight to not have them on the other axles. When the brakes are set properly, I cannot move the truck, with only one axle braking in park.

It sounds like you need to get the brakes adjusted, before you go anywhere. At least check to be sure.

[Robert & Dianne]

My rear brakes were replaced two years ago and the "parking" brake was adjusted and components were replaced. I remember at that time when fuel was applied they held , no movement. You are right, it is time to get them checked again!

[Mustang88]

Don't delay - reminds me of the BB that rolled away when parked on a hill! Went over a cliff and was totalled! Thankfully no one was hurt!

Here in Canada, the Provinces have Air Brake booklets that contain checklist for checking your Air System / Brakes to ensure they are working properly! Might be worthwhile to download.

[Robert & Dianne]

Thank you all
Gardner pointed me in the right direction.
Today I removed the small drawers under the dash to get to the parking brake valve. Sure enough the valve had three 1/4in black tubes going to it. Traced them back and they are the ones which come through the floor in front of the steering column. Removed one at a time and until I removed the one with no air pressure-hoping it was the exhaust tube that is leaking. Blew into it and sure enough it is the exhaust tube under the bus. Aired up the bus using a compressor just to check brake valve under full pressure with no engine noise. The brake valve is bad and exhausts air all the time. Sometimes a lot and sometimes just a little. Did not hear the air before with engine on. Tomorrow I will get a new Bendix valve and hopefully everything will be fine. The Bendix part # just in case anyone else needs a replacement is 289954 PP-1. Also if anyone else has a similar problem there are actually four 1/4in black tubes behind the steering column. The fourth comes from the "turbo manifold" and runs to a "reducing valve" (to 1/8in tubing)and into the turbo meter. As soon as the new valve is in I'll report back.
Once again a BIG Thank you

Robert

[gcyeaw]

Diagrams are wonderful things, Don't leave home without them