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won’t air up to move
Hello all,
Went to the coach this evening to prepare it for tomorrow’s move into the building that will be its home over the winter.
Since I do not have electric hookup where it is now, I shut everything down, inverters off, main power off, engine batteries off and let it sit until now. Sitting like this it slowly sat down oj its belly, I mean fully down.
I wired a little compressor to pump up the belt tensioner bags before I start the engine. Don’t like those loose belts and not being able to put it on high idle.
Well….Started right up, it shows air to 120 psi on both dash gauges, the air puffs every so often but it would NOT come up to ride height, will not lift up on manual, not on Auto, nothing…
I get no air in the auxiliary system upfront either. The gauge stays at 0. I hear hissing from behind the wheels upfront. Some solenoid must be stuck on open and needs to cycle ??
I shut off the engine, bled the belt tensioner bags from the 3 way valve and started it back up on low idle. Normally the bags would inflate in less than a minute. This time nothing. No air coming into the belts bags either.
I pulled out the ride height clear plastic housing relay that sits at the top on top of leveling electrovalves. I can hear and feel it clicking as I pull it out and put it back in. It does the job and energizes the valve but there is no air coming to it.
I pumped the brakes, the parking brake releases, I can put it in drive,
move the bus back and forth a little but the airbags will not
inflate…..not in the front and not in the rear…..sits all the way down… the tire is rubbing on the wheel well top surface foam.Air is not coming upfront……What to do ? Where do I start ?
Thanks.
574 323 8787
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6 Replies
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At about 65 lbs there is a pressure protection valve that opens and lets air into aux system. That said for some reason it sticks. I have found that if you fan brakes /with engine off until pressure drops close to zero on primary ( brake side then air up with engine again if sometimes releases and works as it should. I know nothing about how Liberty modified prevost level low. Do know if you have no pressure on secondary side your bags have no pressure in their supply side to operate in the first place. The purpose of the ppv is to give all available to brake system in case of a major air supply loss. Mine is located in front steer compartment (below drivers window -bottom one. On wall next to level low stack. Mechanical valves stick sometimes- maybe a slight tap will jar it loose.
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I will try that. Thank you.
Meanwhile….Don’t know why the moderator moved the post from the Emergency Help section…..THIS IS AN EMERGENCY !
I have to move the coach tomoorw morning and can not due to not airing up the suspension.
This is not just a comment on chassis….I need all the help I can get and suggestions.
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I had the same problem about a year ago. I replaced the valve that Robert noted. If you can get ahold of your air diagram (download off the Prevost website) you should be able to see it. Mine was in the front compartment (under the driver) in the air line just before the aux air tank (sort of looks like an air regulator without the knob to adjust the pressure) My local Freightliner delaer was able to source one – same day. 5 min install.
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The two most common problems associated with airing up the aux system are the protection valve which affects the total accessory part of the coach iwhich includes everything that is not associated with the brakes, or the center solenoid valve (usually the coil) that affects only the ride height function.
To move the coach without a repair use the aux compressor to air up the accessory side. It might not lift the coach unless you can set it for about 120 PSI.
Then when the coach is stored you can work on the protection valve issue at your own pace. If it is the solenoid valve in the manifold, check its voltage and if it is the same as one of the others in the stack, just switch coils temporarily.
Note to all……….if the air system is not maintained properly, and gets moisture in it all devices within the system ranging from brakes, protection valves, Norgren valves etc. are going to start corroding, and the coach is going to be an ongoing problem. Protection valves have a spring internal to them and when it starts to rust the valves are a hit and miss problem.
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No dice on anything in the compartment under the driver.
Jeff thinks that it is the chack valve mounted on the upper side of the large air tank upfront, passenger side, forward side of the tank….the grey valve on the left of the picture with the thicker black line coming out of the side. Took the picture from below, of course looking up……It is all the way up there.
I do hear air hissing coming from that vecinity when the engine is runnig. I have to lift the coach, prop it up with wood supports and get somehow in there to remove the side air line to confirm that it is not allwing air into the Norgren upfront.
Right now there is no air coming into the front compartment.
I just hooked up a portable compressor that has 150 psi capability and with it plugged into the Aux system and with the key to ON postition I was able to lift the front on manual to the highest level, about 13.5 inches from ground to the structural supports upfront. Now I have to fabricate pads out of 2×12’s and then the fun begins…..I need one of Jeffs skinny boys to get up in there……Boy there is no room…..Even with the wheel fully turned left
Many thanks to Jeff for taking my call and explaining where to look and what to try do.
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That grey valve looks just like the one I replaced. On my vintage coach it was very easy to get at. However, I will note, that mine was not “hissing”. It was not cracking open to let air into my tank.
Your air leak leads me to think something else might be going on. Maybe put your phone on a selfie stick and record a video around where you think you hear the sound coming from.
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