| Author |
Message |
Ron Daniels
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 04, 2006 - 11:34 pm: | |
My 75 MC-8 is significantly leaking air out of the rear main brake valve relay exhaust port. It takes almost 20 minutes tp pump the air pressure up to 90 lbs. I replaced the relay valve with a new valve, and the new one leaks the same way out the exhaust port. I've noticed when airing the bus up that it will air to approx. 30 lbs. & stop & if I hold the parking break down the air will go on up to 120 lbs and then blow off excess air. When I cut the engine off with the parking break locked the air leaks out of the valve relay exhaust port to 0 lbs in less than 5 minutes. I discovered that if I release the parking brake the air stops leaking rapidly. This is not good. Do any of you Busnuts know how I can fix this very frustrating problem? |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 05, 2006 - 2:21 pm: | |
Ron, it's likely your DD3 brake cans or system. Could be a leaky aux. diaphram OR inversion valve, etc. BTDT.
You need to do some step-by-step troubleshooting. Do you have the schematic?
Brian |
Cliff (Floridacracker)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 05, 2006 - 7:30 pm: | |
Ron,
As Brian says its probably one of your rear DD3 brake cans.
I just replaced one of mine for a similar problem on my 4905.
Since it airs up once you release the parking brake it points to one of the cans.
Find the air line that runs from the back of the can to the relay, take a pair of vise grips and pinch off the air one side at a time. This should tell you which side is the culprit.
Since mine was 30 years old I opted for a completely rebuilt one from Bendix(via LUKE) Yeah, there a little pricey but I bet I am not back in there any time soon. I also replaced both air bags while I had the wheels off.
"Once and Done"
Cliff |
Ross Carlisle (Rrc62)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 05, 2006 - 10:05 pm: | |
I had the same problem last year. Replacing the DD3 fixed it. I got a rebuilt from Luke as well. |