When my suspension comes up with air is it supposed to vent some air pressure at some point?
If so, when and why and if mine doesn't then what should I look into?
-Dave
Hi Dave, if the question is really this; "Should I hear venting of air once the bus comes up to level" the answer is no, it should just ease up and quit letting air into the air bellows. (Air bags.)
Jack
Cool, then I seem to be on track. I thought I heard or read somewhere that it should vent sounding sort of like the brakes.
Mine don't, it comes up and stays there with no noise, now I just gotta figure out how to make it stay up overnight!
-Dave
Dave, am I thinking you put the plates on your bellows that block air going into or out of the air beams?
Jack
No, when I pulled the floor out of the bus I found a rust hole in the top of the left front beam. This was caused by a hole by the wheel well allowing water etc to get in and puddle.
For lack of any more sense I cut the coolant lines, cleaned out the beam, welded a plate over the top of the beam where the hole had been, welded a plate over the hole by the wheel well, primed it all with primer, reconnected the coolant lines with 3/4" o.d copper and unions, topped up the coolant again and tried it all out.
Now it comes up smoother that it used to and stays up a little longer (also fixed a leak in the center tunnel area) but pressure is nearly gone by the morning still.
Good deal, just a matter of finding all of the leaks...I guess you know soapy water sprayed on works well?
I am looking forward to the day I see what the condition of the beams on our Cruiser look like. They appear to have been repaired with some pretty heavy duty plates. I am crossing my fongers!
Jack
Yep, sprayed a bunch of soapy water on over and over and probably started the whole rust thing all over again!
Not a leak thank God, I was fairly surprised with my welding skills. ;D
I guess not it's time to look at o rings, tanks,, filters, doo-hickies, widgets and other such things I have little to no knowledge of ...yet.
You forgot...'dumeafltchies'!
Aint this fun?
Jack
By the way, had a truck out west once, couldn't hear the air leak, someone sprayed one of the 'big' air supply lines from the compressor, there were what looked like hundreds of itty bitty holes in it. We never figured out the whole (No pun intended...well maybe a little!) story on how it got that way!
Jack
On air suspension, one point that does leak are the leveling valves. They can appear to be sound, but can leak just enough to let down the suspension over night. I installed my own air suspension leveling system that stays up for about 4 days. I find that when I cut out the automatic leveling valves and have it on manual, that my main air pressure stays up much longer. Good Luck, TomC
"When my suspension comes up with air is it supposed to vent some air pressure at some point?"
The suspension airs up fairly slowly so reaching working height could coincide with the whole air system reaching the blowoff pressure where there is a very loud blast from the dryer (near the front axle in my MC8).
If you don't get that blast eventually - and periodically when you are driving, it could be your compressor is a bit worn and not reaching full system pressure.
Dave,
The leveling valves are usually the culprit. Once the rest of the air system has leaked down (less pressure on the supply side of the leveling valve) the air can leak through the leveling valve back into the air system. When we installed our leveling system, we kept the OEM leveling valves (actually these are "Ride Height" not "leveling" valves), but added solenoids to block the leveling valves from the airbags when parked. Jack
Good information here, now can the valves be rebuilt or are they replaced? I seem to recall a thread on this previously but I'm too lazy to look it up. (Besides, it's nice to keep the related info together) Where would one go to get a rebuild kit or replacement as the case may be and how difficult is a rebuild if that's the case?
Can you also tell me about the solenoids? Are they 24v? Where are they placed and how controlled?
Tom, is this what you also have?
Paladin, If you havent already done so, You need to service your air dryer. The decissant carridge and purge valve should be changed. Mine may have been the only one that was neglected, but I'd doubt it.
Mine was awful, I removed the dryer and rebuilt it all........The purge valve makes the 'blow off' sound that you should hear at 125 PSI
sometimes they are really cruddy and stick.......instructions for repair at www.bendix.com
Parts at MOHAWK 1-800-323-7652 saves $$ over other suppliers
HTH Chuck
Can you guys help the 'tarded boy and tell me where the dryer is?
I'm coming up to speed really quickly being thrown into this, probably in about 5 years or so I'll actually know something! :D
-Dave
The solenoids I used are all 12v since my bus is 12v, but they have 24v along with many other voltages to choose from. I used one normally open and two normally closed solenoids. In between the auto leveling valve and the air bag I put the normally open solenoid. In between the normally open solenoid and the air bags, I installed a T. Off this T I installed another T for the two normally closed solenoids-one hooked up to the air system (T'd into the air supply to the leveling valve) and the other for exhaust. To level the bus, (each position has two switches inside the bus-one for auto or manual operation and the other an on-off-on for either adding or exhausting air) you activate the normally off solenoid, and this cuts off the air path to the auto leveling valve. Then just either exhaust or add more air with the other switch to move that corner up or down. Some take out the auto leveling valves and install 4 systems-one at each corner. But I like the 3 valve system, then all 4 corners are balanced (think of a 3 legged stool) all the time. Also, I like using the normally open solenoid-some use the normally closed solenoid at the cut off point, but then you're relying on the solenoid to always work when going down the road (course you can just go down the road on the manual setting). The solenoids don't draw much current, so during dry camping, it's not really an issue. When really out of level I still use blocks first. Good Luck, TomC
PS- if you have an air dryer, just listen for it to expel when the air comes to pressure, and you'll find it.
I hope this isn't confusing since there are two topics kinda going here at once-Dave, The air dryer is located just behind the front axle on the front bulkhead. You have to block up the coach to be safe while under there, so be careful.
If it isn't purging (blowing off) the purge valve could be cruddy or froze (water collects in the bottom of the dryer and when the valve opens at 125psi, it 'purges' the water out. The purge valve has a heater element that is either 12 or 24v, depending on your application, that thaws the water and lets it purge))
When operating correctly, its easy to monitor your air system fro the drivers seat, even while underway. Just watch your air gauge, at 125+ or - a pound or two, the dryer will purge, the sound under the floor,almost at your right heel. When that happens, the air gauge no longer rises and you can hear the compressor cut out (quit pumping)
depending on your air use or leakage, watching the air gauge, the compressor will kick back on at 90 psi, you'll hear that too, and watching the gauge, the cycle begins anew till the pressure builds to the governor cut out (125) and the dyer purges.
Theres a great air brake handbook on the Bendix web site also that tells what you need to know, and all bus owners need to know how to do the "clap" test.......R.J. Long has the best description of this procedure and most folks have the info bookmarked. Will someone post a link to it?
here a link to the Bendix service page for the AD-2 Air Dryer. HTH Chuck
http://www.bendixvrc.com/itemDisplay.asp?documentID=4852