Couple of questions aboutg air system on class "A"

[DraginRat]

We recently purchased a 2002 Holiday Rambler Imperial through a "consignment" dealer.

While we are generally happy with the coach overall, there were a number of issues.

One of the bigger issues was the air suspension and leveling system was totally trashed. I spent a lot of time on the web learning many things about the coach in general, and the HWH air system in particular.

I pretty much have the air suspension and leveling system back in order, but while many documents I have located tell me how to adjust ride height, there is absolutely no mention of what ride height should be, how to determine what it is, or what it should be.

Also, while putting the leveling system back together, I noticed that the air dryer has been removed from the system. the air dryer (Meritor Wabco system saver 1200) is present, but has been disconnected. Someone connected the line from the compressor directly to the line to the tank with a brass nipple. The inlet fitting had been broken off in the inlet port of the dryer unit, but that was very easy to remove. It appears to be a very simple system, basically in, through the filter, and out to the tank. I assume I should replace the filter canister, but other than that, is there something I should be checking?

Also, how long should the air pressure last once the engine is shut down. Ours drops from 120 psi to about 90 psi in about an hour. Is that normal.

Thanks for any help you can offer

Ken Gasbarri

[Ray_IN]

DraginRat wrote:
Well, I discovered that the park brake button was sticking just a bit open. Had to wait until it got really quiet around here to hear it. Putzed with it a bit and now it does not stick.

I have every intention of replacing the canister before I hook it back up. But, those things cost about $300.00, depending where you buy it, so bottom line, if I need to, I can replace the whole unit.

Well, on to other problems and projects. I think Peg just likes to keep me busy so that I don't wander down to the local drinking establishment.

Ken Gasbarri

The Meritor Air Dryer assembly
might cost $300, but the desiccant filter cost me #38 at a local truck repair shop. Given the Meritor has been out of operation for a long time I would purchase the maintenance kit, which consists of parts to rebuild all the valves attached to the body and a new filter. The kit should cost about $125, call a HD truck repair shop and price the kit. You will find the ID number of the system in your chassis owners manual and on the Meritor casting base. Mine is a Meritor 1200 system.
If you replace the filter yourself, be very sure you clean any/all dirt away from the area first, otherwise you'll get a speck of dirt into the housing and cause you grief later.

[DraginRat]

Well, I discovered that the park brake button was sticking just a bit open. Had to wait until it got really quiet around here to hear it. Putzed with it a bit and now it does not stick.

I have every intention of replacing the canister before I hook it back up. But, those things cost about $300.00, depending where you buy it, so bottom line, if I need to, I can replace the whole unit.

Well, on to other problems and projects. I think Peg just likes to keep me busy so that I don't wander down to the local drinking establishment.

Ken Gasbarri

[DSDP_Don]

Ken.....Call or email Monaco as stated in one of the posts. They will give you the ride height numbers for your specific coach. The front and rear will be different. Provide them with your coach build number.....should be a six digit number located in a couple of spots in the coach, and ask for the build card. They will send you a two page list of everything that was installed in your coach, including serial numbers.

The ride height is adjusted by airing the coach up on level ground. The ride height is measured at the airbags. There is a 1/4" plate on the top and bottom of the air bag, holding it in place. The measurement is taken from the under side of the top pate, where the airbag touches, to the top side of the lower plate, where the air bag touches.

There are two height adjusters on the rear and one on the front. Adjust both rears and then adjust the front. Dump the air and then air back up, roll the coach forward a few feet and recheck the measurement.

The best and easiest way to make the actual measurement is to make a banana shaped tool out of a piece of heavy metal rod. Bend the rod so that the measurement between the two ends, equals the distance required, such as 7 5/8". This allows you to easily slip the tool over the airbag and between the plates.

I found a pair of calibers made in an arc and noted the front and rear measurement on the side in a Sharpie. I checked mine once a year.

There is a rod on the height adjusters that is loosened and then slipped in the direction you need. Only slight movement is necessary and wait for the coach to add or subtract air, to see how much it moved.

As always......when working under the coach on the air system, have safety stands.

[Passin_Thru]

We don't want you to look like Gumby. The test for airbrakes is 1 minute to the floor, no loss. 1 minute engine shut off to the floor, no loss. Loss of air on airbrakes is unacceptable. Dryers are supposed to cycle every time the air reaches max PSI. It is just a P valve and dumps water when it cycles but like they say the desiccant is the poison. Easy to replace on tho.

[wolfe10]

I would definitely NOT hook up the old dryer that the previous owner disconnected.

Only reason to spend the money on fittings and time to bypass is because of a failed dryer.

Yes, there are some failures that would not be harmful to reattach (like finding a massive air leak), BUT if the desiccant has denigrated, reattaching the dryer could spread desiccant powder throughout the air system.

[Ivylog]

Call Monaco ((877) 466-6226) to find out your ride height... probably 7.5" metal plate to metal plate. You will spend a fair amount of time finding that small of a air leak. I would be happy if my dump truck held air that well, but most will say it's not normal. More importantly how well does it hold air when you put the brakes on hard without the engine running and not letting up on the brake pedal?
Before buying a new filter for the air dryer, hook it back up and see what happens as someone disconnected it for a reason... probably a leak that they could not stop. There's more to the air dryer than just a line in/out. Hopefully it's a Meritor style if you have to replace.

[Mr_Mark1]

larry cad wrote:
Air pressure should hold up longer than that. Take a spray bottle with soap suds in it and lay under your coach and spray all the air fittings while you have it pressured up and look for leaks.

And, if you are under the coach, make sure that you have the suspension supported so that you are not crushed if it drops.

MM.

[larry_cad]

Air pressure should hold up longer than that. Take a spray bottle with soap suds in it and lay under your coach and spray all the air fittings while you have it pressured up and look for leaks.