Ok here is more info just returned from 2000+ mile trip. Seems retarder acts up in am. Today much worse. But we are home. When apply brakes and retarder is supposed to engage. It either lights up and engages or it lights up and can hear air leak drops air pressure fast but no help in deceleration from retarder. Retarder does not engage. I think this maybe a solenoid not sure. I can hear problem it is up front somewhere. Also question if it is solenoid because at engagement I am obviously opening solenoid and losing air. Don't know enough about how it operates. Again. Thanks for any and all help. Saw 3 Foretravels on our Journey thru TX, NM, CO and OK
Did you see Pamela and Mike's response to your earlier questions about the retarder acting up (and the air valve)?
Retarder (http://www.foreforums.com/index.php?topic=31493.msg278133#msg278133)
I did see that. The problem I am having is abnormal condition. Sometimes when retarder engages I can hear air escaping below front of coach I have to either turn off retarder/release brakes or elsr air pressure continues to drop. Seems after several cycles this stops and back to normal operation. When working correctly it is great was able to decend Wolf Creek paas with no breaks at all nothing got hot no problems. I am not sure think it maybe air selonoid but would like to verify and not just start replacing parts.
I do not think you would hear the retard if it was leaking air since it is in the back. If you are hearing air hissing it must be coming from some brake component that is under the front.
Not sure i do know when i turn off retarder switch it stops. Also everytime retarder disengages/retard light goes out I can hear air release like pop off.
Build up air pressure. Chock your wheels. Release brakes. Turn off engine. Press and hold down brake pedal. Do you hear air escaping and is air pressure gage dropping? If yes you have a air leak. Check air lines, and brake chambers. You will need someone inside to hold brake pedal while you or helper looks for leak source.
Air pressure up engine off.
The only time I have air leak is when retarder is engaged. Have to be in motion to duplicate that.
This is normal if you have the Joystick and it is in any position other than "off" or 0
Retarder will engage when you back off the accelerator pedal and disengage (light goes out and air release sound) when accelerator is pressed again.
What is happening is not the normal air release I am aware of normal air release this is air that would drain tank if allowed. It is not a quick pop off it is continuous air release. I may try and call Allison and talk to tech.
Breaktime,
Sounds like you have blown the top off of one of the 3 retarder pressure switches. You have 2 other pressure switches in the same area that are for brake lights. Look them over to. You may also look at your brake status solenoids. They are also in this air line loop. I don't remember if the print is an "A" or "B" print but the print # 5894 should have this info and show what I am talking about.
On edit:
Now that Mike has had time to think he said that these items are also on the B-2193 Air line print. Not as much detail though.
Pamela & Mike
The location of my leak is definitely in the front of the coach, i crawled around under there today and cannot find solenoid any idea of main solenoid location?
Also have proved that leak stops when retard switch is opened(turned off)
Description of retarder pressure switch locations on a 1998, might be applicable here as well: RE: Retarder stopped working (http://www.foreforums.com/index.php?topic=10853.msg52198#msg52198)
With photos (same coach) Air pressure alarm and light came on (http://www.foreforums.com/index.php?topic=28814.0)
The solenoids are under the dash. Ours can be seen between the steering column and the outside wall. There is no rhyme or reason as to there location as I have seen them mounted over the brake treadle valve. Some of the pressure switches are mounted in the same area. Some of the pressure switches are usually mounted in the very front compartment (the one in front of the left front tire) close to the steering gear box. This puts them behind the washer fluid tank on some coaches.
Pamela & Mike
Michelle found the old post that gives pics. as to what we were trying to describe.
Pamela
Much appreciated. I will keep digging. Only way to reproduce issues is at speed so troubleshooting difficulty increases. Will keep posted. Thanks.
Here is where I am stumped. After studying diagrams I do not understand why my leak goes away when I switch of retard switch? Do not recognize the correlation. Also leak is definitely in front of coach. I am stumped.
Mike (Pamela and Mike) commented that he thinks the problem is with one (or more) of the retarder pressure switches, and that they are located up at the front of the coach.
The air diagram shows they are fed from the treadle valve (brake pedal).
Electrically they are connected to the retarder.
Not knowing more about how they work, perhaps when you shut off the retarder, you remove power from the switches and thus they cannot open up and leak.
Air Schematic shows the connections to the air system. One of the electrical drawings shows the connection to the retarder control.
I did find pressure switches, i believe what i am looking for is a solenoid because a pressure switch would not change with power either applied or removed, on pneumatic diagram i see accumulator but no solenoid i will dig out electrical schematic and try that. I know that under normal conditions when retarder disengages and air is released that happens in front of coach as well I am thinking this is solenoid in question just cant find it.
The help is much appreciated will keep posted.
I believe this or similar is what I am after.
ALLISON TRANSMISSION - VALVE ASSEMBLY - SOLENOID, RETARDER P/N 29557354 | eBay (http://www.ebay.com/itm/ALLISON-TRANSMISSION-VALVE-ASSEMBLY-SOLENOID-RETARDER-P-N-29557354-/201863513727?epid=2085987857&hash=item2f0000c67f:g:KjUAAOSwJAtZOLhO&vxp=mtr)
That's the air valve located on the transmission (back of coach) that Mike mentioned earlier (Retarder (http://www.foreforums.com/index.php?topic=31493.msg278133#msg278133))
Photos of the location in Dick S's attachment here Replacing transmission retarder valve (split from What did you do to your coach) (http://www.foreforums.com/index.php?topic=17318.0)
See also Dave Steven's post here for a photo Big Air Leak Hydraulic Accumulator (http://www.foreforums.com/index.php?topic=15185.0)