When I apply my parking brakes, I get a squealing sound from the air system. First I thought it was coming for all brakes or it could be coming from something in the last bay. If I play with the pull (air) switch it will go away, sometimes.
How much is this going to cost me :(
Thanks in advance for the input.
Bill
Hi Bill,
Sounds like your brake switch is in need of a rebuild or replaced, something is not seating properly when you hear air bypassing making a noise. That is why sometimes you fool with it and it goes away. Air valves that make noises are usually gummed up or worn out or both.
Paul
Paul,
Where is it located on a MCI-9?
Thanks for the help.
Bill
Bill,
Does the parking brake button have air lines to it? Not sure if its similar to mine or not. It might be a switch that activates the valve, the valve is where the problem could be. I am sure others who are familiar with MCI's can be of more help. Where is your parking brake button located?
MCI owners please provide Bill with your expert knowledge.
Paul
Paul,
Yes, I believe it is an air switch.
Bill
The brake light switch is in the spare tire compartment up next to the brake valve (up on the floor level)
You have to lay on your back and crawl in to get to it. 2-wires and Napa or any truck place will have compatable switches in stock.
Mine was leaking and whistling , I looked at the book and it is rebuildable but for $5 it was easier
just to change it out. Screwdriver and pair of pliers. 10 minutes of pain...
Dave....
Brake Light Switch ??? ??? ??? Really ???
But the sound seems to coming from the last cargo bay.
Bill
Sounds like you may have a blown parking brake diaphram on the brake cans. If they leak, they can back feed into the other cans and make a hissing sounds. Good Luck, TomC
Could the Inversion Valve be the problem?
Bill
Think Tom is right. Get it safe to release the brakes, listen for air leaking at the drive axel brake cans with the brakes released. If it leaks under these circumstances, you are out of service on the spot until the brake can is replaced. Don't burn your bus down.
Hello Bill.
DD3 brakes, the kind on your MC9, require a little diagnosis to properly identify the right strategy to keep as much of your money in your pocket and time spent replacing parts to a minimum.
As noted earlier, get the bus into position to crawl underneath, block the air suspension so you are safe, run the bus to fill the air system, and turn the motor off, to be sfe and so you may hear, then carefully seek out a source of leaking air, spray bottle of soapy water at the ready, under these three conditions:
parking brake released
parking brake released, full brake pedal application ( need a stick or a helper)
parking brake applied
restart engine and rebuild air as neccessary, not with you underneath, please!
You will want access to the relay valve exhaust and the inversion valve exhaust at the rear, and the brake pedal exhaust up under the driver, against the bulkhead, follow the brake pedal linkage. Also familiarize yourself with the location of the pressure regulator attached to the inversion valve and check it too while you are under there, just for external bubbles. It should be air tight.
You must note from where any air is coming out. The source of the air, under which condition, will pinpoint the offending circuit or part.
Thanks, I will start looking for that in the next couple of days.
Had plan to start looking today, but, as luck would have it, it wouldn't leak.
Thanks again.
Bill
Guys,
In the passenger side rear engine door, above the transmisson, are two air regulators. The one on the right, is leaking. Could this be my problem? What does it take to rebuild this?
Thanks for the help.
Bill
Currently in Phoenix
AND there's more,,,,,
Looks like the bottom of what I believe is the Brake Valve, located under the driver in the driver tool compartment, it is leaking on the bottom.
How do I rebuild this?
Again Thanks,
Bill
My suggestion is to buy factory rebuilt/exchange components for the brake air system.
Quote from: Kwajdiver on June 11, 2007, 01:29:22 PM
Guys,
In the passenger side rear engine door, above the transmisson, are two air regulators. The one on the right, is leaking. Could this be my problem? What does it take to rebuild this?
Thanks for the help.
Bill
Currently in Phoenix
Bill, the air regulators are a snap to rebuild. The "book" even describes how to do it. Call up US Coach Repair and order the rebuild kits. Pull the regulator, replace the perishable parts and reassemble. Then get out your shop air and a pressure guage to set the correct pressure and tighten down the lock screw. Put the air regulator back on the bus and your done!
One of the simplest repairs possible on these beasts.
-Brian
Brian,
What's the number, will call you in the morning?
What about the other part that is leaking, does it have a rebuild kit? That would be the part under the driver in the driver tool compartment.
Thanks,
Bill
Okay,,,,
Looking in the MCI manual. I believe my big problem of this ungodly squeal of air leaking is coming from the R-12 Rear Brake Relay Valve. Will go looking for it in the morning.
Any input on this is welcome.
Bill
"In the passenger side rear engine door, above the transmisson, are two air regulators. The one on the right, is leaking."
Just so you know, the RH regulator sets the tag axle suspension pressure - 35psi. The RH regulator is the tag axle unload pressure - 15psi.
To the left of these is a valve that switches between the two. Even if you don't have a tag unload switch on your Left drivers panel, the components may still be there.
If you check all the other regulators in the bus, you may well find many of them with slow leaks - usually quiet, slow leaks that add up in total.
Some of us have a dream about getting to the stage of having a leak-free bus (oil or air) -- but after a while the urge passes and you just get used to starting the engine a few minutes earlier and buying oil in bigger tins.
Tonylee,
Thanks for the laugh this morning. I'm sure you are correct.
Also found the E-10 Brake Value leaking on the bottom. Is this anything to be concern about?
Bill
Hello kwajdiver
The air leak out the bottom of the brake pedal valve occurs under what conditions? parked, released, pedal released, pedal applied?
Any leaking brake valve is NOT your friend.
My schematics have gone missing.... a leaking DD3 parking diaphragm will exhaust out of another service brake related valve, fooling you into replacing a perfectly good valve, only to find it "leaking" again. Probably the relay valve down the back is where.
If you want to have a go at rebuilding the valves or regulators, feel free, but you might want to price a replacement and decide if your time, and the risk of finding the casing damaged, is worth it.
I replaced those same tag axle regulators a few years ago, IIRC, $42 to replace each, kit was $22 each.
happy coaching!
buswarrior