View Full Version : Ride Height Failure Driver's Side

04-18-2017, 10:26 PM
I am a new member to POG but have enjoyed reading the articles for several years. I have a 1993 Angola conversion which will not reach ride height on the driver's side. The driver's side seems to lift slightly but not enough to allow the mud flaps behind the tag to clear the ground. I have not been able to discern any obvious audible air leak. I attempted to level the driver's rear thru the Level Low system. It will not lift any higher but will allow air out to drop down. It appears that some air seems to be getting into the rear bags. The previous owner had the R & L leveling valves replaced by Prevost Fort Worth in 2012 as well as other valves/bags in the past. My primary and secondary air pressures are 120 psi on the dash. A Prevost Nashville representative stated that it was satisfactory to drive the bus several miles to my local mechanic in its present state but i am hesitant to do so. All five Level Low solenoids were replaced in 2007. I would appreciate any guidance that is available. Thank you in advance.

Joe Camper
04-19-2017, 06:13 AM
If u cant get to ride height by either allowing the bus to do it automatically with the ride height valve or manually with level low on that left rear u either defiantly have an air leak or that spool valve on that corner is really messed up.

There could be 2 different things going on too.

Quincy I'll is not too far from me. I could figure that out probably pretty quick if I got my hands on it.

04-19-2017, 08:35 AM
Dan, Joe is the man on Prevost, he can make things happen.

04-19-2017, 08:39 AM
Sounds like either a faulty ride height control valve or a stuck norgren spool valve at that corner. There was a wonderful animated presentation that Hector Duplichen did many years ago describing the Level-Low system and the collection of HCV's, Norgrens, and solenoid operated control valves that make up our suspension control system. I think it was entitled "Prevost Air Systems and the Leans" or something like that. I can't find it. Do you guys know where it is?

If you go to the Prevost Car site and scroll to the bottom under "Resources" and click on "Webinars" it'll bring you to a page featuring lots of interesting webinars, one of which is on "Level-Low". You'll need to open it using Internet Explorer. When you do you'll be asked to install Cicso's WebEx extension. Once done you'll be able to view any of the 30 or so webinars on the site. No registration is required.

04-19-2017, 09:58 PM

Yep, Joe knows these suspensions and everything else under the coach.

Your symptom is pretty weird given the level low and ride height when in drive position don't have anything in common besides the bag or it's ping tank. Maybe, it's a tag axle problem. If you lift the tag does your symptoms change?

Here's the great training overview Hector put together that David was referring to: (CLICK HERE) (http://www.texasdrifters.net/pog/Suspension%20revision%2012-18-2009-1.pdf).

04-19-2017, 10:14 PM
Many thanks to all for your advice. I was fortunate enough to have spoken to Joe earlier today who gave me some diagnostic ideas. I have passed that information along to my local technician who has maintained my coach for the past 3 years. I will air up the bus tomorrow evening and lift the tag as Gil has suggested. Thank you for the link to the air system diagrams. If my local efforts are not successful, I'll be back in touch with Joe to arrange for his services.
Thanks again, Dan

04-20-2017, 07:26 AM

Thanks for posting the link to Hector's work. It's fantastic! I recall when Hector first did it. He held a few online seminars (webinars) that folks could subscribe to where he narrated the presentation. I guess none of the seminars were recorded. Thanks again!

04-20-2017, 09:19 PM
Gil, thanks for the advice for lifting the tag axle. I aired up the bus, left rear will not lift, switched to Level Low in attempt to lift left rear with no improvement. Switched back to drive, lifted tag and bus left rear came up promptly with perfect centering of the bubble. After dropping the tag back down, I noted a prompt drop again of left rear. I turned the bus off, audible air leak noted from behind the driver/tag wheels but unable to locate. The leak disappeared at about 110 psi noted on my dash primary and secondary gauges. Thanks for your help. Dan

04-22-2017, 04:08 PM

I would look at the Norgren valve supplying air to the tag bags. The valves are difficult to get to as the are located high and between the tag and drive axles.

05-03-2017, 11:51 PM
The final diagnosis to my problem is a leaking right tag bag. Bag replaced and coach levels fine. Thanks to all for your input. My next project is to solve my air horns. Tag bag did inflate and bus nearly leveled, my technician stated it was a split that was just above the base which leaked as the bag unraveled. Increasing ambient temperature seemed to make it more challenging.

05-04-2017, 07:05 AM

Great news. That bag was probably original. 23 years of service is not too bad.

The air horns shouldn't be too hard. There's nothing more than an electrically operated air solenoid to make them work. Hopefully, the solenoid is easily found in the compartment under the driver's seat. Maybe a dumb question. If you have a switch for city/air horns, is it in the correct position?

05-04-2017, 03:29 PM
Gil, thanks for the reply. I do not have a switch for air/electric horns but I'll check. I've been chasing this in the past, thought it was in the button, dismantled and freshened contact points with Emory cloth, my local tech changed horn relay in the driver's outside compartment and worked sporadically. We chased the solenoid to behind my front bumper above my house batteries. I do get a click I can hear where relay is located, don't think it's the solenoid and no sound. Previous owner told me to clean diaphragm from wasp nests which I've done to no avail. I haven't explored the ground button against the drive shaft as noted from an earlier forum. I did note a thread about position of the tilt wheel ( think it was telescoping). I'd like to hook up my electric horns so I can produce a reliable sound.

05-04-2017, 09:46 PM
I will clarify, I will check out horn contactor on the steering shaft per prior thread

05-04-2017, 09:53 PM
If the problem is sporadic, then you are probably headed down the right path. The only other thing I'd check is the grounding.

If the problem is in the steering wheel, then adding electric horns won't help. I don't know when Prevost started installing electric horns, when they did, they were often installed in the floor in the bay under the driver's seat and covered by a plastic box.