New to me Prevost - Level low issue

joe · August 02, 2012, 05:27:01 PM

One issue only determined after I purchased this fine machine. Is I have very slow air leak.

I can level the bus and after an hour have no detectable air pressure loss on the primary or secondary gages. In fact the primary will hold air for several days with no detectable loss. But overnight I get a definite list. The passenger side drops and she ain't level by morning.

Does your experience point me to look any any particular area first. I can start soaping every joint but if there is a common problem I'd like to start there. Without a shop and working this in a field/parking lot is not going to be fun.

robertglines1 · August 02, 2012, 05:50:41 PM

Joe: on the other board at top in the articles section is a complete tutorial on the level low system unique to prevost. Prob in one of your norgen valves. Might cure it's self but you need to watch it very good . Bob. Everyone else welcome to watch it at prevostcommunity.com very educational on air leveling systems.

stevet903 · August 02, 2012, 06:06:54 PM

I had a leaking leveling valve on the rear of the side that was low - there are three leveling valves on the bus, two in the rear and one in the front. There should be no air leaking out from the exhaust when the bus is level and turned off. That's the simple one. The level low system uses a number of Norgren valves to control the height of the bus. There is a manifold in the compartment below the driver - another easy place to look for leaks. I second the tutorial - very helpful.

Steve

luvrbus · August 02, 2012, 06:08:05 PM

Are you sure it is a low level system or a HWH leveling system either way start at the manifold and the electric control valves plenty of places there for leaks have fun

It has to be a leak after the protection valve it closes at 70 lbs and will not let air into the suspension system that is why they drop

The bus setting for those years check the plastic lines the Texas rats love that stuff so do welding sparks and grinder sparks

good luck

joe · August 02, 2012, 06:30:08 PM

Quote from: robertglines1 on August 02, 2012, 05:50:41 PM
Joe: on the other board at top in the articles section is a complete tutorial on the level low system unique to prevost. Prob in one of your norgen valves. Might cure it's self but you need to watch it very good . Bob. Everyone else welcome to watch it at prevostcommunity.com very educational on air leveling systems.

I found it and will watch it. The air diagram is scary!

joe · August 02, 2012, 06:34:26 PM

Quote from: stevet903 on August 02, 2012, 06:06:54 PM
I had a leaking leveling valve on the rear of the side that was low - there are three leveling valves on the bus, two in the rear and one in the front. There should be no air leaking out from the exhaust when the bus is level and turned off. That's the simple one. The level low system uses a number of Norgren valves to control the height of the bus. There is a manifold in the compartment below the driver - another easy place to look for leaks. I second the tutorial - very helpful.

Steve

Can I get to the valves in the rear axle without a pit or lift? Are there connections near the passenger front (like in the spare tire compartment) similar to those in the steering compartment? or is the only thing over there the air bag connection?

joe · August 02, 2012, 06:37:47 PM

Quote from: luvrbus on August 02, 2012, 06:08:05 PM
Are you sure it is a low level system or a HWH leveling system either way start at the manifold and the electric control valves plenty of places there for leaks have fun

It has to be a leak after the protection valve it closes at 70 lbs and will not let air into the suspension system that is why they drop

The bus setting for those years check the plastic lines the Texas rats love that stuff so do welding sparks and grinder sparks

I'll start checking all the exhaust ports I can find for leaks. If I find one (or more) is the best course to replace or rebuild the valve?

I vacuumed the bays last Saturday and did not see any signs of rodents. Maybe I'll be ok in that area.

robertglines1 · August 02, 2012, 06:45:14 PM

Your in for a real education here LOL::: ck leveling valve first soapy water is your best friend here. Replace leveling valves-- if needed not that expensive... spray all over air bags and connections.. If you have any push type connections pay particular attention to them. I feel your pain. Bob

robertglines1 · August 02, 2012, 06:50:37 PM

prevostcar.com is another good source for pneumatic diagrams particular to your coach--pre converter. takes last letter in your serial # plus last 4 digits(your unit number) If you need help getting thru their site just ask. Bob

luvrbus · August 02, 2012, 06:51:41 PM

They are scary Joe as my friend Bobofthenorth says a very over engineered air system on Prevost's don't crawl under the bus working on those it comes down in hurry play safe block it up or your wife and someone else will enjoy your bus

Those were always a problem that is why most have the HWH system and like Bob I feel for you could be a easy fix maybe not so easy

robertglines1 · August 02, 2012, 07:16:44 PM

Need to look at system but if I remember correctly when you are in level low your level ing valves are out of system. I know they are. been about 4 months and 7 new norgen valves since I worked on it and 40 hrs studying diagrams. 8 new air bags.many feet of new air line.What a experience. Smile ..

robertglines1 · August 02, 2012, 07:22:05 PM

5ea 24 volt coils 3 leveling valves 8 shocks 10 bushings Just thought I'd make someones day. Don't plan on doing it again!!! Bob

PP · August 02, 2012, 08:20:54 PM

Hey Joe, I've been fighting a slow leak on the driver's rear for the past 5 years. I thought I had it at one point when i discovered the fitting at the top of the air bag was actually loose. I tightened that, replaced the seals in the little cast air cleaners (probably had nothing to do with the level low, but the system held air for a while longer after that). After several gallons of soapy water now, I've extended my system from holding level overnight to almost a week. If I'm going to be parked longer than that, I carry 4 stout wood blocks just for the rear. I set it down on the 4 blocks and then level it front to rear with the front air bags, they hold air forever it seems. Just make sure before you crawl under that beast you set some good blocking. That's a lot of weight being held up by mere air pressure. As TomC would say, "Good luck".
Will

RJ · August 02, 2012, 08:38:12 PM

Joe -

Just an FYI - I've seen brand new Gillig Phantom transit buses, with less than 250 miles on the clock, sitting cattywompus in the bus yard the morning after being delivered by the factory.

Such are the joys of air suspension!

FWIW & HTH. . .

Ed Hackenbruch · August 02, 2012, 09:30:24 PM

I have one bag that will sometimes hold for a few days just fine, then the next time we move and i adjust the level, it will go down in a day or so. Can't hear it leaking anywhere, soapy water doesn't show anything, i think i have it narrowed down to a worn o ring in the push-pull knob for that bag. It will leak down about 1 lb an hour. Need to find the right size and shape, (Think they are a flat o ring? ) and replace. Just a pain to get to because i have to take out the seat to get to it.