H3-40 owners with an air dryer question

[Bruce_Fay]

My wife Linda and I purchased a 1991 H3-40 Royale Coach conversion back in Sept 2009. I have been a POG member for a while, but not active on the site or in the forums. We plan to retire July 1, 2012 and hit the road with our two cats and hope to cross paths with other POG members somewhere down the line.

I have a technical/repair question and wasn't sure where to post it, so I am putting it here. If there's a better forum for this, someone please let me know.

I need to replace the Bendix AD-4 Air Dryer. The AD-4 is obsolete and Prevost supplies the AD-9 as a replacement. The mounting brackets are different, etc. Just wondered if anyone had any experience with this upgrade? and what the appropriate Bendix part number(s) are? At a minimum this involves: 1) the dryer, 2) the mounting brackets, and 3) a wire harness/connector. I am having trouble determining if these come as a kit or have to be ordered as three separate things, and potential sources besides Prevost ($$$). Also, will the AD-9 simply install in place of the AD-4 in terms of mounting location/holes, air line connections, etc.?

Thanks, Bruce

[gmcbuffalo]

Why not just get a new element for the existing dryer? Mine is a 91 XL 40 and I found a dryer element for it and it is an older version of what you have.

[BoaterAl]

Bruce, i just googled "Bendix air dryer" and it came right up. Keyed the first pick on the page.

I would assume you just need a cartridge ? Most any truck shop with a good tech can change out a air dryer cartridge.

Have you tried NAPA ?

AL

[Coloradobus]

Our's is a 1992 Chaasis XL, and we have the air dryer that has the desicant loose in the container. All that needs to be done with it, empty the old granules, and put in new and tah dah.

[Alek&Lucia]

Hello Bruce,

Follow this link below:

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=Bendix+AD-4+Air+Dryer&_sacat=See-All-Categories

If you travel by us stop by for few days, we have plenty of room for you.

It will be nice to meet another Royale owner


Alek

[Bruce_Fay]

Thanks for the quick replies. It's encouraging to know that folks are watching and responding to the forum threads. The problem with my AD-4 is not the desiccant element, which is easily replaced. The dryer itself appears to not be working correctly. I can still get rebuild parts, such as the purge valve, or even the entire base plate assembly, but our unit has a 24 V heater and 3/4" ports, which is not the normal/common configuration. Most of the units available on the web, or from places like NAPA, are 12 V heaters with 1/2" ports which is what is used on over-the-road trucks. If you take a coach to Prevost to have a defective AD-4 replaced, they will replace it with an AD-9. I just figured it would be easier to upgrade to a current unit rather than fix the old, obsolete one. I was hoping that some POG member had experience with this and could tell me what's involved.

[Jon Wehrenberg]

Bruce,

You don't say if your plans are to have someone else replace the dryer, or if you ntend to buy a newer modle and do it yourself. Whatever you choose is obviously your decision. If I were dealing with the problem you describe I would recognize two things. First, whatever decision I make has to consider the Prevost is 24 volts and that is what the heater must be. I am sure Prevost or any aftermarket supplier can get a dryer with a 24 volt heater. That includes NAPA. It just might be a special order.

The second consideration has to be future maintenance. Early dryers used on our coaches were somewhat difficult to service compared to the types with a spin on cartridge for example. If I were to change dryers I would seek out the one easiest to maintain. All dryers can have the bottom end rebuilt so a second consideration would be to pick one that was easy to rebuild although it is unlikely you would ever have to do so if you maintain it with regular cartridge or dessicant changes.

Replacing it does not have to be done by Prevost, and if it were me I would either do it myself or shop around and find a truck repair or bus repair facility to do it.

[Orren Zook]

I need to replace the Bendix AD-4 Air Dryer. The AD-4 is obsolete and Prevost supplies the AD-9 as a replacement. The mounting brackets are different, etc. Just wondered if anyone had any experience with this upgrade? and what the appropriate Bendix part number(s) are? At a minimum this involves: 1) the dryer, 2) the mounting brackets, and 3) a wire harness/connector. I am having trouble determining if these come as a kit or have to be ordered as three separate things, and potential sources besides Prevost ($$$). Also, will the AD-9 simply install in place of the AD-4 in terms of mounting location/holes, air line connections, etc.?
Thanks, Bruce

Everything you mentioned should be included as part of the AD9, or WABCO 1200. All the rebuild parts are still available for your AD4 too. I'm not sure how Prevost has the heater unit wired in but on OTR trucks in is wired to the cab heater switch. Did you check the heater unit with the dash heat on? It is only really needed at initial startup - once your compressor has run a while it is making hot air which keeps the dryer unit thawed out in colder climates. Here's the WABCO part number for the 24v unit: 650-R955206 Meritor WABCO 1200 System Saver Air Dryer.

[truk4u]

Bruce,

I just rebuilt my Meritor/Wabco 1200, it is the cartridge type and very easy to rebuild once you get to it. I have had both, the cartridge and the refill one, the cartridge type is the way to go. I would think the airlines can all be adapted, so a little plumbing may be in order. This is what mine looks like if it helps.

9080

9079