Remove leveling valves - install manual system

[richard5933]

I know that other people have done this, so I hope I can get some idea of what is involved in removing the OEM leveling valves and installing a system that can be manually controlled.

Two goals: Allow for some degree of manual leveling at a campground, and eliminate the problems I have with the factory setup going out of adjustment.

How much plumbing needs to be run? What type of manual valves and gauges, etc.

Trying to see if this is a practical idea.

[chessie4905]

You don't need to remove leveling valves. You install Bendix double check valves near every
Leveling valve. One port is connected to original valve. The front air bags are seperated during manual leveling, revert to factory in highway position. The other port is run up to a control panel where it is convenient to you. Panel has a selector valve to chose between highway and camping. Panel also has 4 mini pressure gauges, and 4 air ride seat push-pull valves. About 150 feet of 1/4 inch air line, assorted tees and elbows, etc. I had the system in our 4104. Installing one in our 4905. All done except for assembling components on panel. I want to post copies of original system papers and include a list of the components and part numbers/ brands of each item. Just haven't got around to it yet.Btw, on mine, I purchased different color air lines for each corner for any diagnostic issues down the road.
Some connect leveling valves to choke cables and do it that way. Since the one in the 4104 worked well, I stuck with it. I'm using all dot lines and fittings. I don't know whether it is necessary, but I'm a little anal/fussy about things.

[richard5933]

Ok, so I don't need to remove the leveling valves. But could I?

Don't know why, but I'm constantly finding they're not keeping the bus at the correct height. When I was at Luke's last fall, Bill spent over an hour trying to get the rear set correctly. He thought that it was done, but after just a few hours on the road the bus was about 1-1/2" off left-to-right.

My guy in Milwaukee set it again when we got back. It held for a while, but on the way to the shop to have the Jakes installed it went out again. Parked in the shop's lot and was down on one side again.

They adjusted it, took for a test drive, and when they got back it was tilting the other way. Same issue Bill encountered.

Any advice? Both rear valves were replaced at Luke's, twice just to be sure.

[dtcerrato]

Wondering if the feed lines maybe experiencing intermittent blockage or sluggish response due to dirty filters.

[richard5933]

Wondering if the feed lines maybe experiencing intermittent blockage or sluggish response due to dirty filters.

If you mean filters at the leveling valves, there was nothing there when they were changed. Bill was totally stumped - he said that he'd never had such trouble trying to get a GM to sit even with the pavement. The air system in the bus is pretty clean as well, nothing but water comes from the drains (which are drained every day I've got it on the road).

[daddysgirl]

This might sound like a stupid question, but could the leveling difference be the result of weight?
I remember someone had a similar issue last year, and (if I'm remembering correctly) they had to set the valves differently to accommodate the weight on the right side.

This thread is older, but there is a lot of good information:
https://www.busconversionmagazine.com/forum/index.php?topic=6868.0

[chessie4905]

The original leveling valves used a glycerin fluid that worked for a delay. The repair kit came with o-rings, new check valves, and a bottle of glycerin. Was a total pita to rebuild them. Throw them out and get universal ones from Luke.

[Dave5Cs]

Supply line from Accessory tank to valves and four 1/4" lines. one to each corner at bags. I left in the leveling valves just in case I ever want to hook them up. I measured the body off the ground for correct clearance when driving and found that 85 in the rear and 80 in the front works well. In a campsite I just lift or lower according to my inside levels on dash and side panels. 

[dtcerrato]

A difference in weight should not effect a properly operating valve. It is weight transfer that tells the valve through geometric change in the leveling arm that air is to be added to or expelled from the air beams. Richard were any of your valves replaced at US Coach? It would seem to me that would be the next move. I have a rear leveling valve that gets finicky once & awhile. It normally operates ok but if you go to screwing around trying to level with it, it will make you crazy. I wouldn't ever do away with the original triple valve set up for obvious reasons. Have you ever  noticed that a three legged stool normally sits with all three legs on the surface it's setting on where a four legged stool will usually rock unsteadily? (Hint) 

[dtcerrato]

Hi Dave I think we posted almost simultaneously. Maybe MCI & GMC are different air bag specs. Da GM book shows 75 psi as max amount of pressure on the air bags...

[chessie4905]

Is that spec for the double donut type? We had the 4104 up to 90 to 100 psi occasionally with no issues. Course the bags were in good shape, no cracks.

[Jim Blackwood]

Dave, that is a great looking control panel, I'd like to build something similar. Are those valves or switches?

Jim

[richard5933]

Supply line from Accessory tank to valves and four 1/4" lines. one to each corner at bags. I left in the leveling valves just in case I ever want to hook them up. I measured the body off the ground for correct clearance when driving and found that 85 in the rear and 80 in the front works well. In a campsite I just lift or lower according to my inside levels on dash and side panels. 

Four controls and only two gauges - do you have a way to read each corner's pressure independently?

[richard5933]

A difference in weight should not effect a properly operating valve. It is weight transfer that tells the valve through geometric change in the leveling arm that air is to be added to or expelled from the air beams. Richard were any of your valves replaced at US Coach? It would seem to me that would be the next move. ...

Yup. I had the bus in Luke's shop last fall. The last thing Bill had on the list was to level out the side-to-side situation for us, but it took him hours. He was frustrated not being able to do what he says is normally easy. Both rear valves had already been changed with new ones from Luke, and Bill changed them again on the outside chance they had been clogged up with something in the air system. Still had problems.

The thing will keep parallel to the road for months, and then on a weekend trip will list to one side so much that we roll out of bed.

The original leveling valves were designed to keep the bus level as passengers got on and off as well as baggage being loaded and unloaded. Since out weight rarely ever changes more than a little bit, I was thinking that it might be time to go to a manual system. It would allow me to set the ride height as we needed, and it would allow me to make some adjustments at a camp site to accommodate a wonky site.

[buswarrior]

Hang on... roll out of bed?

Is this levelling problem while driving, or after the air has bled down while parked?

Axle is slightly askew parked... air bleeds off, the leveling valve on one side is calling for lift... the air EMPTIES via the now lower pressure supply line, back to the tank and away via the little leaks.

The other side isn't calling for anything and stays sealed up...

Some valves have check valves, some don't, some have failed, as an aside, this is how to crush a busnut quickly, the coach simply lowers when the pressures balance, or worse, the busnut empties the tank, doing maintenance...

There's always a reason, keep digging. Busnut use is unique, and the obscure conditions sometimes stump the pros, used to traditional fleet use conditions.

Nobody cares about a an occasionally leaning empty seated coach.

Happy coaching!
Buswarrior