Author Topic: air dryer troubles  (Read 5976 times)

Offline revbusnut

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air dryer troubles
« on: February 21, 2007, 05:40:33 AM »
Dryer is constantly leaking.  Bus will only air up to 60lbs.  How can i get enough air to realeae brake to move to ramp or pit.  Do I need dryer, Part number??? 1978 MC-8.  Thanks for help.   I have tapped it with long 2x4 and leak changes but will not stop.  Thanks, kevin

Offline ChuckMC8

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  • 1977 MC8 and 1993 102C3 Temple Ga #322 F&AM
Re: air dryer troubles
« Reply #1 on: February 21, 2007, 06:18:26 AM »
kevin- the purge valve on the bottom of the air dryer is stuck open. Take a 1" x 2" appx 4' long.  thread a wood screw into the board, appx 1" from the of the board, and leave the head sticking up about and inch.
   On the bottom of the dryer, youll see the protrusion thats about 1" diameter, (thats where the air is leaking from)
 reach under the bus with your new "tool" and hit up from the bottom with the protruding screw on the board. It will tap the valve shut and all will be cool..........'ll need to service your air dryer. You need a decissant cartridge (on ebay for cheep) or Mohawk.....and you need a purge valve kit. Most air dryers on our buses havent been touched in years
(Unless we did it!) anyone who has a bus should do the air dryer service. Theres great tech info and a toll free help line at     hth- chuck
« Last Edit: February 21, 2007, 06:20:19 AM by ChuckMC8 »
Far better is it to dare mighty things,to win glorious triumphs,even though they may be checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much,because they live in the gray twilight that knows neither victory nor defeat.  Theodore Roosevelt (1858-1919)


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Re: air dryer troubles
« Reply #2 on: February 21, 2007, 06:36:01 AM »
kevin,mine does that when it needs service too,but i take the 1/4 inch line off for a few seconds when it gets up to 50or 60lbs and it starts to works

Offline jjrbus

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Re: air dryer troubles
« Reply #3 on: February 21, 2007, 07:38:39 AM »
Mine stuck on me in the middle of the street!!! Luke told me to take a long stick and without getting under bus or making sure it is securely blocked, tap on the bottom of air dryer. It worked for me. If it does not work try Chucks way. If that fails go to Kevins. Sticking is a sign that it needs to be rebuilt. However when I did mine nothing looked dirty, worn, nasty ect. But it is all new so should last for some time. Now I always carry a big stick.
Remember, even at a Mensa convention someone is the dumbest person in the room!


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Re: air dryer troubles
« Reply #4 on: February 21, 2007, 07:48:59 AM »
If you’re in or near freezing weather….read the following.

New or Remaned Air Dyer with inoperative heater will still leaks.

Caution….never drive it any where except into warm garage or tow to have it repaired.
Otherwise…you are in risk of inoperative brake control pedal’s valve….froze valve spool due to moisture freeze…pedal working but…NOOOO….Brake.  Been there and being fortune to be in yard slow moving before out in street.

A good working air dyer and heater is your safe guard to prevent inoperative braking. Alcohol vapor system is not your main guarantee but air dyer with heater is.
So if you plug the bleeder…don’t risk driving anywhere until it repaired.

More than likely your air dryer’s heater is not work either no electrical power to it or burn out….heater only warm up bleeder valve to keep from icing if during in or near freezing climate. Check for broken wire, poor connection to air dryer and bad 3 amp circuit breaker in Rear Junction Box of master bus bar (#3 Black 16 GA. wire on 1974 MCI 8 ).  Or bleeder valve stuck open….less likely.

To get it temporary remove icing via heat gun or heat lamp with no air pressure in dryer….otherwise rushing bleeding air will  keep it from warming up to thaw.

Remember heater element in air dryer is Only to keep bleeder valve from freeze while running…..but not to heat air as you may think.

Read Bendix Handbook on page 7, 9 and 12:
Bendix Hankbook

Sojourn for Christ, Jerry
« Last Edit: February 21, 2007, 08:03:21 AM by Sojourner »