[Ed]

see diagram in articles on suspension leaks

[Archived]

see diagram in articles on suspension leaks put in level low has colored pictures

[Archived]

Joel, as soon as I read that, my impression was the two five port Norgrens in the rear are not returning to the neutral position with the key off. If they do that the air is locked in the air bags.

But my initial impression upon further thought questions a failure of two Norgrens in the same way at the same time because each side of the rear is independent of the other. So my concern is that a failure of the Norgen five port valve located on the bulkhead forward of the rear axle is the only way air in the bags can escape through the Norgren to the ride height valves which will leak air but only until the rear settles to ride height. I hope that makes sense. If not I can explain my thinking more in detail.

What would do that is in my best guess two Norgrens that might have moisture in them, particularly at the airline coming from the center solenoid valve on the 5 valve stack in the steer compartment being moisture laden.

If you can please follow up on this because it will be a help for all of us to understand what is happening and what we all can do to make sure we don’t experience it.

[Davy]

The actual problem with the coach that led me to discover air seeping slowly from the exhaust tubes of both rear level control valves is that the right rear settles (below ride height) after about a day. Left rear is much better/not noticed.

After checking for external leaks, I found the seepage at both level control valves. The rear valves have not been changed in my ownership history (2006) and may be original…the front valve was changed a few years back. Does this help any? If the norgrens should close off the level control valves, I would suspect both rear norgrens have probably just been dying a slow death. Right rear dropping after about a day has been going on for maybe a year.

[Archived]

Joel, it does sound as if both the ride height valves and the Norgrens are the issue, especially given their age. If the bus continued to drop lower than ride height then that is the clue the ride height valve is contributing, but is not the sole problem.

[Darrell]

Dreaded air issues and level, sinking problems. Had Prevost Houston, after my Yearly Level 3 service, adjust ride height because it was leaning ever so slightly to right after it aired up. I thought it was a front ride height problem. Tech told me usually the rear. Raised back a little but since adjustment it will drop rear after a few days where it didn’t before. Front will stay up for weeks after adjustment. Always something. Maybe Gremlins.

[Dan]

Well, I think I’ll start with a right rear norgren and go from there. Pretty old anyway.

[Archived]

After wearing myself out chasing leaks one at a time on my first bus and finding every time I turned around another popped up, I use a 10 year plan for air bags and Norgrens. I probably waste a lot of money, but it has eliminated hours and hours of frustration chasing my tail.

I do my own work, and I can only imagine the pain watching someone try to find and repair leaks one at a time. They would waste more time and money than it would cost to just do the whole system.

[Dan]

one suggestion As you replace lines and fittings go to compression dot fittings— the push type seem not to be happy with temp changes and to loose their seal after awhile.

[Bernard]

I always use compression fittings.

[Jeff]

Bob, following your suggestion I went to “Articles” on this forum and found two entries. One of them is described as applying to early 102″ models with 8V92 engines and the other is described as applying to 1980s vintage coaches.

Do you know if the first diagram has any applicability to mid-90s coaches with Series 60 engines?

Kirby

[Jeff]

Kirby, Linda……..if you go to the Prevost Car web site, parts and maintenance section, publications you will find you can pull up the pneumatic diagrams for your coach. They are valuable because they not only show how the air system is plumbed, but the diagrams are so detailed they show the orientation of the individual fittings.

[Archived]

Thanks, Jon. I will do that.

Kirby

[Archived]

you coach Prob has a T or U as last letter in serial # (yr prevost made shell) then last 4 numbers your unit numbers.. Will give you coach specific diagrams.. IE mine is W-6554. Enjoy life now! Bob

[Roscoeapproved]

UPDATE: right rear norgren only solved the right rear problem. I imagine the left will go next but at this point the left rear stays up for several days…good enough for me! Thanks for the help.

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Jeff and Lindsay

91 Marathon XL