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Author Topic: Won't air  (Read 1789 times)
Tikvah
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« on: October 11, 2013, 05:57:27 AM »

Started my bus this morning and it wouldn't build air.
I know what it is but at the same time I don't....

Under the driver seat, behind the bumper is a air device thar is bleeding a lot of air through a rubber seal on the bottom.  It seems to be related to the brakes.

It won't close

What is it? What do I do?
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
Tikvah
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« Reply #1 on: October 11, 2013, 06:01:48 AM »

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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
luvrbus
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« Reply #2 on: October 11, 2013, 06:07:16 AM »

I would say it is brake related that looks like the bottom of the brake treadle ( pedal)
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Dave5Cs
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« Reply #3 on: October 11, 2013, 06:54:38 AM »

Dave try taping it on the bottom. There probably  something stuck in the exhaust end. That like Clifford said is your brake valve from your peddle. It is stuck in the open position

Dave5Cs from Galaxy S III
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Lin
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« Reply #4 on: October 11, 2013, 09:05:53 AM »

You could also try reaching down and pulling the pedal up.
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Tikvah
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« Reply #5 on: October 11, 2013, 09:20:17 AM »

In the garage now.  Brake peddle is right, but still don't know if it needs replaced or cleaned, or rebuilt.  Either way, I think it's been leaking for awhile.  
I'll keep you up to date.

Could it be a back-feed from something else?
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
Tikvah
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« Reply #6 on: October 11, 2013, 12:51:08 PM »

The problem:


And the solution:
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
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« Reply #7 on: October 11, 2013, 03:15:41 PM »

Okay, that's not the solution.  Something is backfeeding through the valve system in the pictures above.  We don't know what.  Any ideas?
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
luvrbus
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« Reply #8 on: October 11, 2013, 03:25:48 PM »

Crimp the hoses off to the D3 brakes one side at a time if that checks out then check the quick release valve your being a dual air system there is a check valve between the 2 systems also
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Tikvah
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« Reply #9 on: October 12, 2013, 10:39:51 AM »

Could I get you or someone good with air brake system on the phone please?

Dave
231-330-3615
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
bevans6
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« Reply #10 on: October 12, 2013, 12:18:59 PM »

The exhaust port on the bottom of the valve is what lets air out of the piping after the brake application is released.  If air is there when it shouldn't be, it could be because the foot pedal isn't letting off all the way, but it's probably coming from the R-8 relay valve at the rear of the bus.  The upper section of the E valve is the primary section and works the rear brakes by sending air through a small line to the R-8 valve.  If you disconnect and cap off the small line at the R-8 end, the exhausting air may stop - if so that tells you it's the rear brakes.  The relay valve gets it's main air supply from the primary service tank to feed the rear brake cannisters, but it's remote-controlled by the treadle valve through the small relay line. Air could be feeding back from the relay valve, is what I am thinking.

Just noodling the issue, I'm not that familiar with dual brake systems.

Brian
« Last Edit: October 12, 2013, 12:22:34 PM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Tikvah
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« Reply #11 on: October 13, 2013, 05:57:19 AM »

Friday we replaced the treadle valve under the driver seat, then we found feedback through the push/pull valve while in park.  We replaced the push/pull valve without success.  Now we spent all day Saturday removing the inverter valve in the back.  With stuck bolts and broken lines it took most of the day.  We cleaned the inverter valve and hope to re-install that today with hopes that the problem is fixed.

If anyone has ideas I'm all ears....very frustrating day yesterday.  Not knowing if we're even doing the right thing.

Dave
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
Oonrahnjay
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« Reply #12 on: October 13, 2013, 06:10:27 AM »

  Friday we replaced the treadle valve under the driver seat, then we found feedback through the push/pull valve while in park.  We replaced the push/pull valve without success.  Now we spent all day Saturday removing the inverter valve in the back.  With stuck bolts and broken lines it took most of the day.  We cleaned the inverter valve and hope to re-install that today with hopes that the problem is fixed.

If anyone has ideas I'm all ears....very frustrating day yesterday.  Not knowing if we're even doing the right thing.    Dave 

      OK, I wouldn't know a DD3 if you hit me over the head with one, but if you've got feedback through the push/pull parking/emergency valve, that would make me look more and more a leakage between "service" and parking chambers on one or more wheel cylinders.  Did you get a GOOD clamp off of air through the braided brake hoses running to each of the chambers when you did the test that Clifford described above?
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
Ralph7
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« Reply #13 on: October 13, 2013, 06:20:52 AM »

          You did not pinch off the air supply to the park brake at the rear brakes!!   That is the first thing to do. A bad diaphragm on one/both will allow air to escape through the R-8.
     Got mine from Luke, while in there one of the big ones was chafing so changed it.
     717-582-78three 3
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luvrbus
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« Reply #14 on: October 13, 2013, 06:52:54 AM »

Inversion valves are in the parking brake system they are open till it get a air from another source to close very seldom do they have a problem,there should be a shuttle valve not far from the pedal 

They function just like the name implies it shuttles air to different ports It would sure help if we knew what foot valve is in that bus a E what ?,I still think it is a DD3 problem
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Tikvah
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« Reply #15 on: October 13, 2013, 07:26:36 AM »

Maybe I'm confused, what is a DD3?
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
luvrbus
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« Reply #16 on: October 13, 2013, 07:45:48 AM »

The DD3's are the brake chambers on the rear axle they have 3 air lines going to each one
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Tikvah
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« Reply #17 on: October 13, 2013, 07:59:11 AM »

Oh, that is not what I thought.  If it has three lines, how do I pinch one off?   Which one?
If there is a leak between the chambers, wouldn't it leak both directions?  I only get bleed-back when in park.  Since we fixed the treadle valve everything is fine when the park brake is released.

Won't be able to test anything else until we get the inverter valve back in place.  The MCI manual says to clean and service the inverter valve every 50,000 miles.  My guess is that it has never been serviced.
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
luvrbus
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« Reply #18 on: October 13, 2013, 08:17:18 AM »

Take 3 pairs of vise grips to crimp the lines one side at a time ,a trick I use is slide a piece of pipe over the jaws on the vise grips that protects the rubber line from tearing and gives you a better seal

I think you are in the wrong place with working on the inversion valve those are open you have a DD3 problem I believe I have been wrong before tho       


good luck
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bevans6
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« Reply #19 on: October 13, 2013, 08:39:07 AM »

DD3 brake cannisters have three air lines going to them, and two chambers.  The air line closest to the push-rod end is the push-rod lock.  With no air pressure it locks the push-rod out to hold the brakes on, with air pressure applied it unlocks the push-rod and lets it operate normally in and out.  The middle air line is the service or main brake chamber.  Air goes there when the pedal is applied and forces the push rod out to operate the brakes normally.  The third air line closest to the back of the chamber is the parking/emergency chamber.  Air goes in there when the parking brake is applied to push out the push-rod and apply the brake.  What is a common cause of DD3 issues is a hole or leak in the parking brake diaphragm lets air leak into the main chamber when the parking brake is applied.  That air has to come out somewhere - it goes backwards to the R-8 valve, and from there can go to the E-6 foot valve and come out the exhaust port.  The first clue that this is what is happening is the air leaks out and makes a noise when the parking brake is on and there is air pressure in the parking brake section of the DD3.  The second clue is that with the parking brake applied and the noise/air leaking out, if you clamp off the center/main air line, the noise stops quickly, or if you clamp off the parking brake line the noise slows down and stops when all the air in the parking brake chamber leaks out.

The inversion valve is what sends air to the locking port and the parking brake port.  It's fed through an 85 psi pressure limiter, and is under the control of the parking brake push/pull valve.  If the push/pull valve is set to parking brake on, the inversion valve dumps air from the locking port to zero so the locking port can lock the push-rod out, and it sends 85 psi to the parking brake chamber of the DD3 to push the pushrod out and apply the brake.  If the parking brake push/pull valve is set to release the parking brake, the inversion valve flips over and sends 85 psi air to the locking port to let the push-rod unlock, and dumps air from the parking brake chamber to release the brakes.  You do a 100 psi brake application to fully release the brakes because the push-rod has to move out a tiny distance to let the locks actually release from the push-rod.

That's DD-3 and inversion valve 101...  

Brian

« Last Edit: October 13, 2013, 08:42:13 AM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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« Reply #20 on: October 13, 2013, 09:21:18 AM »

Both the DD3 and spring brakes use a inversion valve but work the opposite I am taking it for granted he has DD3 springs either way it has to have a signal to work 
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Dave5Cs
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« Reply #21 on: October 13, 2013, 10:36:15 AM »

Do you have an air dryer if so there is a check valve inside it if its an AD-2 if AD-9 with the screw on cartridge there is one on the out going line that if stuck open would let air go back instead of building or holding it. It is in the big nut looking thing coming out at the top of it. By the inversion valve there should be a double check valve also.

http://www.anythingtruck.com/category/htp-brake-air-valves.html
Above link will help you identify parts in the air system. HTH

Is air still coming out the peddle valve

Dave5Cs
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Tikvah
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« Reply #22 on: October 13, 2013, 10:55:29 AM »

The third air line closest to the back of the chamber is the parking/emergency chamber.  Air goes in there when the parking brake is applied to push out the push-rod and apply the brake. 


Is this accurate?
Air normally releases the brakes? ?  ?
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
bevans6
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« Reply #23 on: October 13, 2013, 11:41:24 AM »

Tikvah, it takes three things to release the parking brake.  It takes air pressure at the locking port (closest to the push-rod end), it takes zero air pressure at the parking brake port (the back of the cannister) then it takes a pressure application at the service brake port (the middle port).  So the inversion valve sends air to the locking port and exhausts it from the parking brake port to release the brakes.

You have applying the parking brake right - the inversion valve sends air to the parking brake port to extend the push rod, and takes in away from the locking port so it can lock the extended push-rod.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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« Reply #24 on: October 15, 2013, 02:25:36 PM »

Ok Dave what was the fix ? don't leave us wondering  Roll Eyes
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Tikvah
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« Reply #25 on: October 15, 2013, 03:57:22 PM »

No answer yet.  We have driven the bus to Grayling and the problem persists.  We did find a leak in what we think is a shuttle valve attached to the inverter valve.  However, even though that shuttle valve leaked, and has been replaced, I still have air coming from my treadle valve while in park.
We have pinched the lines to the brake chambers without results.  My only guess it that it's a brake chamber and we simply can't pinch the lines well enough.
The coach can be driven, the air leak is not an issue when the park brake is not set.
I don't know what to do next, maybe take it to Brecheisen Diesel in Gaylord.  I hope to talk to them in a few days.

I can tell you that Greg, with Pacer Service Center in Muskegon has been the most helpful, kindhearted, and giving people we met in our time in that city.  He spend his whole weekend working on our bus, on his own time, just to be helpful.  We left almost in tears from our gratitude for his kindness.
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
bevans6
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« Reply #26 on: October 15, 2013, 04:51:29 PM »

My next step, with what you have described, would be to remove the hoses from the service (middle) port on both DD3 chambers and put the parking brake on, and see if air came out.  Be aware that if you are driving the bus, if your parking brake diaphragms are indeed leaking you also have impaired emergency brake capability.  They are the exact same thing.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Tikvah
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« Reply #27 on: October 16, 2013, 06:04:59 AM »

Are the brake chambers for the MCI-9 and my 102 A3 the same?
I see a pair on ebay
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
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