Air parking brake won't release?

[EricW]

Parked my 97 bluebird with air brakes in January and haven't released the parking brake since. Now when I push the button to release it I don't hear that nice escape of air. Any ideas where to start? I'm thinking somethings just stuck

[Arvik]

maybe hole in air line somewhere, does it come up to pressure?

[turf]

air brakes need air..... they are engaged when they have no air to hold back the pads. check your compressor, air dryer, tanks.

its possible that some water froze in the system and did damage.

there should be a schrader valve somewhere in the system so you can air up the brakes to move the bus.

[johnbloem1974]

I would crank the engine to get the tanks filled, and you should be able to release the brakes... After that long a time, I'm not sure any vehicle would have any air left in the tanks...

[EricW]

The tanks seem to air up. One makes a whining noise until it's full of air. I have some valves labeled wet, back brake and front brake and I drained the air out of those and let the tanks fill up and they still wouldn't release. I am going to go check it out more tomorrow but am not familiar with air brakes so it's hard for me to speculate on what could be wrong. I was hoping maybe something just got a little stuck

[2kool4skool]

Air up, chock the wheels, release the pkg. brake and crawl under with a hammer and give the rear drums a good whack.

[Roadrunner]

Agree with @kool4skool. Just make sure you chock the wheels REAL good. The shoes tend to rust/stick to the drums when it is parked. We would sometimes hammer the shoes EASY if there is room in the backing plate.

[Robin97396]

Eric, it would be good for your bus in the long run if you at least warm it up once in a while during the winter. Take it for at least a 15 minute drive every couple weeks so the engine warms and other moving parts move.

[Arvik]

try releasing brake putting in drive and giver her a little (not a lot). the movement may just release them.

[2kool4skool]

Yup, R to D and back, see if you can rock it a bit.

[Robin97396]

Yeah, usually shifting from drive to reverse several times will jolt them enough to cause them to release. It's better than crawling underneath and beating on the brake drums.

[crazycal]

Originally Posted by johnbloem1974

I would crank the engine to get the tanks filled, and you should be able to release the brakes... After that long a time, I'm not sure any vehicle would have any air left in the tanks...

If you mean crank with the starter until you build up pressure, that's a bad idea

[Robin97396]

Even with a big battery I don't think you could build up enough air pressure by cranking the starter.
His bus already runs and builds pressure. Just needs to rock it back and forth or beat on the drums as a last resort.

[Night Roller]

Take it from a truck driver, it's best to chock the wheels, let the bus idle until warmed up & the air systems are up to operating pressures, push in the brake release, & leave the bus run until the pressures are back up to normal. This may take 15 minutes or more depending on how well your Air system & brakes have been taken care of.
Rocking the vehicle (start by putting it in reverse first) is a way of checking to see if they are loosening, but ultimately knocking on the drums is usually needed.
good luck, & be patient.

[johnbloem1974]

I guess I should have clarified that I meant crank the engine to get the engine running....then with the engine running, the tanks would fill......



John

[cadillackid]

how high does your pressure get? if you push the park brake release in. . and then pull it back out 15 seconds later you should hear an air release... these are your Spring brakes...

if you dont hear an air release when you pull the release back out then likely you are never pressurizing the rear brake air cylinders.. all the rocking back and forth in the world wont release them if they arent getting pressurized when you press in the release..

your bus should either have 2 air gauges or a singke gauge with 2 needles.. originally they were green and orange needles..

you need to make sure both are coming up.. if only one needle is coming up or your pressure is not coming up high enough then you cannot press in that yellow park-brake release and expect it to release those springs in the rear....

-Christopher

[bansil]

when you chock the wheel make sure you chock them on both sides so it can not roll forward or backwards, 1st time may make you pee a little

I have a pc of steel rod I use so I am away from tire some, insert end on top of shoe resting against the web, tap a couple times with 2 pound hammer, you can see if the pads are stuck to drum

make sure you have air pressure built up and bus in neutral!!!

again chock tires on both sides and do not have arms or legs under the tires when they brake loose

[opus]

Before you go under it, release the brakes, step on the brake pedal hard. 9 out of 10 times that will release them.

[REDD]

....seized slack or "S" cam?

[EricW]

Haven't gotten back to the bus... working retail blows. I'm going to try the hammer on Thursday and hope for the best.