2002 MADP Air leak

[Spk64]

If anyone followed my problems in WV last month. There was one item that showed up or I just started noticing after breaking down and needing to be towed.
While being service in the shop I noticed the air bags leaked down really quick. While there it was aired up and really could not locate any leaks. So I went on my way and finished out the trip with out any issues but noticed the compressor seemed to be cycling about every 90 seconds which seemed like a lot. The air pressure on the primary tank stayed at around 125psi unless I used the brakes then it would go down some. The secondary tank was the tank losing pressure.
When I got home had Spartan provide the air systems diagrams and I started to try and determine the problem.
Per the system diagram primary tanks provide air to rear brakes and the secondary tank provides air to front brakes and air suspension. I aired up the system and shut the motor off so I could look for leaks. Immediately I heard a leak from the rear and it was worse on the left side. Quick peak underneath and noticed the ride height valve seemed to be the source. If I pushed up on the lever it would slow down some. The leak was from the exhaust on the valve.
Here is the valve and the air was leaking from the exhaust tube.

So a quick call to Spartan and I had a replacement shipped. I may have paid a little more going through them but was not positive of alternate part numbers. Spartan's PN 1870-MM5-801001 which is actually a Haldex 90054007.


I was also concerned with when the dryer may have been serviced last. Luckily there was a date on the cartridge 9/14/13, and the change frequency is 2 years so it was serviced and I will replace soon. I had drained the tanks last summer and no water came out of tanks, drained them today and they were also dry. So cartridge seems to still be functioning.

My air bags are starting to show some cracks but no leaks yet. Looks like those will also be replaced in the near future.


With the new valve in hand I took on the task of replacing today. Working on the suspension or any thing underneath the RV is nothing to take lightly. So I decided to put as many safety's in place as I could.
I built ramps to raise the tires 4.5" which keeps me safe if all the bags are lowered. Along with the ramps I put my leveling jacks down and a pair of jack stands. These were both at the ride height setting. Chocked front tires.


And as another safety item I added an aluminum block between axle and frame.


After that it was a simple task to remove the old valve, transfer the fittings and reinstall.
Old vs new, new came with fittings but they were wrong size and tubes would not have fit with the straight fittings.


Followed the instructions on setting ride height. Which is basically with rod removed air system up to the proper height. Install alignment dowel then replace linkage at this location.
Linkage removed and dowel removed to cycle air bags up to ride height. Never set by lowering to ride height.

The wood dowel in position to lock in the linkage at ride height.

After this is set just remove blocks between frame and jack stands and jacks. Lower air bags and let them go back to ride height. Double check the number. In my case 8-1/4" from center of axle to bottom of frame rail.

One item that got me was be sure to keep the nuts for mounting the valve and the linkage separated. The valve uses locknuts and the linkage uses a nut with lock washer.

After I replaced the valve the compressor airs up and stayed steady at around 120psi on both tanks, Could not hear any air leaks! I am hoping now the system will actually not leak down as quick and going down the road will be without the compressor constantly cycling. The motor and compressor actually sounded a little quieter without trying to constantly overcoming the leaking valve.
Next weekend we have a short trip so I can test things out.

Now that that is out of the way I can move on to oil and filter changes for engine and transmission. Sent out samples for both to be tested before the change to see where I am.


Steve

[Spk64]

Well overnight and system leaked down considerably. Front air bags down but rears are still up.
Tanks are below 50psi.
So back to checking things out.
I did notice that my wet tank drain seemed to not close completely when I released it but was thinking it was due to pressure being very low. Given the low pressure on my tanks seems to point me in this direction.


Steve

[Spk64]

Aired up today and got out the soapy water. Found 2 items leaking.
This is the air protection valve that supplies the air suspension. Per the diagram it should be a 60psi cutout but Haldex shows the lowest at 70psi in the premium version which this appears to be. (Haldex 90554107)
Picture not that great but large bubbles blowing out side.

Here is a better picture.

Also found a leak at the 2 way check valve that supplies air to the parking break valve.
Leak is on the square valve where the cap bolts on. I am having trouble finding a part number or picture of this one.

Both leaking valves on left side of image.


Tomorrow I will call Spartan for the correct part numbers. These leaks are really small so no immediate action required.
I checked most of the other areas and did not see any other leaks. Hard to fully test brake system as brakes need actuated to test everything.


Steve

["007"]

Excellent write up SPK64 will be following your progress, owning a older coach does need items replaced over time and the know how to do it is a big plus especially a DP COACH.
Just for the heck of it make a estimate of hours required and against dealer pricing you may have saved.

[Spk64]

Thanks 007!
It is hard to put a full estimate on my time or what a dealer may have taken as the problem was intermittent at times.
So my rough guess on this is 2-3 hours for everything or maybe $2-300 in labor at a dealer at a min. plus whatever dealer markup on parts and supplies.

I may have spent a little more time tracking it down and getting prepared with doing the actual work. I can confidently say that when I am finished I will have a much greater knowledge of the system.

And yes and older coach is always in need of something. I fully expected this going in. This is one of the reasons I purchased a slightly older coach but higher end in its day. I spent about $30,000 less for this coach as another newer coach yet 4 years, it was not as nice and really felt like I would have spent more on maintenance than what I am spending today. My budget/estimate was to keep it under 10k for getting systems all updated and functioning correctly. This included a new set of tires.




One more note related to the air system for everyone else.
The lines are all color coded and these color codes are on the air diagram from Spartan. This makes it much easier to determine what is what on the system.
Blue lines are for suspension.
Red lines are front brake system
Green lines are rear brake system
Orange lines are parking brake





Steve

[bruceisla]

Thanks for the great comments and pictures !!

[Drewfab]

Did you ever resolve your front air bags leaking down overnight? I have a similar situation as you, I replace the rear valve because it was leaking pretty good, but the fronts leak slowly, after a day or two the front bags are empty but the rear bags stay up where they should be. Was it that pressure protection valve or the front ride height valves?

[Spk64]

My front air bags still leak down in a day or two. Prior to replacing the valves on the tank my tanks would also be empty. Now the tanks hold pretty good at 60-65 psi. I may look for the leaks up front but they are of no concern for me at this time.

[Dav L]

Nice write up. Was thinking of buying one of those height valves as online they are very cheap. Mine airs down in a day (like yours). Maybe some day I will get motivated to find it...