'95 Marquis ride height control troubleshooting

[John Fitzgerald]

Greetings, I am a new member and just bought a 1995 Marquis last Wednesday, I joined about a week ago hoping for a lead on a used coach and one that fit my needs popped up on Craigslist a few days later.  It has some issues, first of all the ride height is not correct.  My reading of this forum discussion of the problem indicates that I should probably start with checking the ride height control valves.  Can anyone verify that the correct part for my coach is a Haldex Midland RN10JC.  The previous owner was trying to track the issue down and thought the HWH level system was the culprit, but it appears that system switches to control of the ride height with these mechanical valves when travelling.  The coach is still in his yard (he owns lots of other big rigs) so I don't have access to the manuals until I head back to continue TS.

thanks

[Fred Brooks]

    John,
   Does the coach have HWH Computerized Leveling System?

[John Fitzgerald]

yes it does

[Steve Huber Co-Admin]

John,
If travel height that is the issue and the coach levels normally otherwise (assuming it has air leveling) it is probably one of the 3 ride control mechanisms that is at fault. There is one in front (center) that controls front to back height. The other 2 are just inside the rear wheels and control side to side height. It's a relatively simple adjustment if you are going to do it yourself, but you MUST take some safely precautions. If for some reason the adjusting mechanism fails, the coach will quickly drop to minimum height, crushing anything in its path. Place hardwood blocks or 20 ton jacks under the  frame to keep it up in case of loss of air. The adjuster control mechanism is simply a radiator clamp that holds an arm that controls the amount of air entering the airbags.  I believe for your coach the air bag plate to plate distance should be set at 9.75" - 10". The exact measurement should be in the owners manual.
Steve
See http://beaveramb.org/forum/index.php/topic,9888.msg67479.html#msg67479 for picture of adjustor.

[John Fitzgerald]

Thanks, I am going to attempt to do it myself.  I will be getting all of the needed cribbing and stands.  I work in an industrial setting and am used to moving around heavy equipment.  You only need something that weighs 30,000 pounds to fall on you once to ruin your day.

[Fred Brooks]

   John,
  The reason I asked the question was to make sure what leveling system you had. My next question was when you start the engine and let it build air pressure, does the "green" travel light illuminate on the HWH control panel? What does the air pressure gage stop at eventually? Is the coach level front to rear or leaning to which side? Fred

[John Fitzgerald]

Sorry, I can't answer most of those questions yet, the air does build up to over 100 psi.  I was using the PO's control panel to read out the resistance of the components as a first step.  He thought the HWH system was controlling travel height and I was following his thinking/advice until I actually read the HWH docs. online.  I am just out of the gate on this one.

John

[Fred Brooks]

   John,
When the air pressure reaches 100psi , the accessory air tank starts to feed the air ride syspension. This is the green needle if you have a single gage on the dash with a red and green needle. (the red needle is dedicated rear brakes only) The "travel light" on the control pad means the "6 pack solenoid" block for the front and the other 6 pack for the rear are now sending air pressure to the height control valves to achieve proper ride height. Hope this helps, Fred

[John Fitzgerald]

Great info, thanks.  I am trained in pneumatic controls from back in the 80's when most HVAC commercial and industrial controls were pneumatic.  I am just getting up to speed in the air suspension and brake worlds.  I think I get about 90% of what is going on in the HWH system.  I had some first incorrect assumptions that were passed on from the seller about what was wrong.  It is kind of cool to see what must have been absolute state of the art in the 1990's inside the control box!  The RV techs must have kind of freaked out when they removed that cover back then.

[John Fitzgerald]

I don't know if anyone is following this, but my 'work around' for getting the rig to my place next week is to supply constant twelve volts to the circuits feeding the solenoids in the six packs sending air to the chassis ride height valves.  It appears the system is not doing this automatically.  I will the do a total check and rebuild of the system when at home base.  It is good the the manuals are in the coach, and spending some quality time with them has helped.  I can see how having a shop do this work could get pricey real fast.