More info needed on air dryer filter changing procedure

[wagonmaster2]

Hey Cruzer - You are very well informed on diesel maintenance. I read all your previous threads on air dryer removal but need more info. Do you have to drain any air tanks to relieve pressure before removing the air lines? Can you explain how the push-in works to remove the air lines? Approximately how much does the dryer weigh when the bolts are removed (it will drop down but it will have to be lifted back up in place while laying on your back - I hope I will be hefty enough for this). Since you have an Allegro Bus is it on the Freightliner Chassis which is what I have? Can there be very much difference in air dryers? Please forgive the long questions, but I'm relatively new to the diesel scene and eager to learn as much about them as I do about gas chassis. Thanks for all the details you can pass on.
Wagonmaster2
2004 Meridian 36G

[wagonmaster2]

Hey Cruzer - You are very well informed on diesel maintenance. I read all your previous threads on air dryer removal but need more info. Do you have to drain any air tanks to relieve pressure before removing the air lines? Can you explain how the push-in works to remove the air lines? Approximately how much does the dryer weigh when the bolts are removed (it will drop down but it will have to be lifted back up in place while laying on your back - I hope I will be hefty enough for this). Since you have an Allegro Bus is it on the Freightliner Chassis which is what I have? Can there be very much difference in air dryers? Please forgive the long questions, but I'm relatively new to the diesel scene and eager to learn as much about them as I do about gas chassis. Thanks for all the details you can pass on.
Wagonmaster2
2004 Meridian 36G

[Hooligan]

Haldex has good info on their website, tech bulletins etc under "Resources". Instructions for the dryer kit are here http://www.hbsna.com/pdf/literature/L31120%203-02.pdf

I replaced my filter and cannister from underneath, took maybe 1/2 hour. I did have to loosen the mounting bolts to get to one fitting, but did not have to remove air lines. Be sure all air pressure is off the system. You should have lanyards on the drain valves for the tanks.
Bench repair may be the way to go, since it was 80 deg here when I did mine.

Hope this helps..

[Hooligan]

Instructions above are for the Pure Air Plus system, if you have the PURest Air filter, this may apply http://www.hbsna.com/pdf/literature/L31175%209-02.pdf
and--I have not worked on this one..

[Radarr]

We were Gaffney earlier this year and while at their factory service center for some other work, which was under warranty, I had them replace the air dryer. Our coach had about 25,000 miles on it and it's not been subjected to any high humidity.

From that experience, I have to say, it took their qualified technician a little longer then expected to do the job, that was suppose to be simple. IT IS NOT ALL THAT SIMPLE...

When they were finished, asked to look at the old parts and asked them what they thought the condition of the parts. The service manager, said, the condolesent filter(???spelling) wasn't that bad and that I could have gone another year maybe, if we weren't in a high humidity area and if I kept the air tanks blead on regular bases.

Well, for those of you "IT MAKES ME FEEL GOOD" guys, it made me feel good to know that the system was doing it's job and what I have been doing, helped. Although, I am glade I didn't try replacing the dryer filter myself, becuase it really wasn't that easy. I hate did hate to part with the $175 it cost me to have this done, but after seeing what the tech had to go through, it was well worth the aggrivation I would put myself through.
I also noticed, that the tech replaced a back box(10"long x 8" high), some sort of electronic control unit. I don't know why, but I didn't question him and just let he do his job. I have to say, that our FreightLiner Chassis runs out just great, straight and true. Also thanks to the CAT 3126 and the Allison.

radarr

[Cruzer]

Wagonmaster2,

The air dryer connects between the air compressor and the first (wet) air tank. The wet tank is check valved so it "shouldn't" leak back. I did fan the brake pedal anyway, just to be sure. That way if any air does leak out it'll be minimal and over quickly.

The push-in connectors are pretty much standard nowadays. The nylon or plastic line just pushes into the adapter. In order to release the line you squeeze the adapter together and the line pops out. I also squeeze them when reinserting just to be sure that the line is going in all the way. It's very similar in operation to an air hose quick disconnect coupling.

The dryer isn't that heavy. I don't know the exact weight but I can hold it up easily enough with one hand while inserting the bolts with the other hand.

My Bus is on the Freightliner XC chassis and I have the Haldex PurEST filter unit, which I understand was fairly new as of the 2004 model year. The unit comes apart and the desiccant filter is easily removed. I believe the earlier models had a spin-on desiccant cartridge which was easier to change but did not have the longer lifetime of the PureEST design.

Hooligan's link is the correct one for the PurEST version.

High humidity does play a role in air dryer life cycles. The more air you pump through it, the more moisture you will pump through it. Therefore high mileage will shorten the years that you'll get out of it. Also, driving in the bayou will shorten the lifetime of the cartridge compared to driving in the desert. Draining the air tanks is always a good idea. It will let you know if there is a problem when you suddenly see lots of moisture coming out. However, draining the tanks will not affect the life of the air dryer because they are located after the air dryer, not before it.

[wagonmaster2]

Thanks for all the great information everyone. Being a newcomer to the diesel field I don't know what I'd have done without this forum. When I first read about the air dryer filter in the maintenance manuals I assumed the spin-on filter was as simple as the engine oil or fuel filters - - Boy was I wrong there. I also assumed the filter would be in the open where it could be reached but it looks like there is some kind of cover with 4 small bolts that has to be removed before even getting to the filter. Even the pictures in the September 2005 FMC explaining the air systems don't show a very good likeness. Thanks again.
Wagonmaster2
2004 Itasca Meridian 36G

[wagonmaster2]

This may be a 2nd post, the other one just disappeared. I just crawled under my coach and looked again at the air dryer. I can see one line into the bottom with the push-in connection but the other one has a steel web outer lining and screws onto the pipe connecter elbow. I couldn't find any label as to type or brand. Is this one different from the Haldex? All this is what makes diesels so confusing. No one seems to know what type of oil or size of filter the tranny needs, what kind of anti-freeze is in the radiator, how many fuel filters the engine has or how many quarts the crankcase holds (I've read even some mechanics are putting too much oil back in after changes, whether or not the fan pulley has a grease zerk, and the list goes on. After working with gas vehicles for 50 years where none of these are problems, its all very confusing. I'm still trying to get all the maintenance figured out after 18 months.
Wagonmaster2

[RedT]

My sentiments exactly, Wagonmaster2! Welcome to the club! Have experienced the same frustrations, especially after asking the folks that made the thing and they don't know!!

Problem is, the engine manufacturer and the accessories vendors DON'T know what their product is installed on. The OEM's don't really track (by model, style, etc) what parts go into their product.

Sure makes for a fun DIY experience! <G>

And, then the "expert" at the campfire says: "Well, on my coach.........."