Decisions Decisions which air dryer

[Paso One]

I have two perfectly good operating Bendix Air dryers.

My bus was not equiped with a air dryer, however since putting the engine back in and hooking up all the lines.

I decided this was an ideal time to plumb one of the two, my delima is which one to install.

The one as you can see from the attached pictures has a extra tank and drain.

I was orignally planning on installing the one without the extra tank and drain as my bus still has the heated moisture ejector valve  expello ( pre air dryer )  tank plumbed in further upstream.

What one would you instal?

[belfert]

What model is that?  If I was going to go to all the work of installing an air dryer I might install something more modern like an AD-9.  Remamufactured AD-9s can often be found relatively cheap.  During fall and early winter truck parts places often have specials on AD-9s.

[luvrbus]

Those AD-2 are good dryers repair kits are getting a little hard to find now but parts are available from Napa install the one with the ping tank keep the other for parts

good luck

[bevans6]

The ping tank will catch the worst of any free oil or water by condensing it out of the air stream before the air gets to the dryer.  It has a valve to drain on the bottom, on my bus it says "drain daily".

If you drive in colder temperatures make sure you have an operating heater for the purge valve.  The rapid expansion of the air as the purge happens cools it dramatically and they can freeze up pretty easy.

Brian

[Paso One]

 Brian: The actual installation should not be much trouble as I have lots of room within 6 ft of the compressor.

Clifford  Yes, indeed it is the AD2 units, thanks for confirming. Should be lots of kits available around Canada  as I see them lots.

Brian  Considering this bus spent it's life in  Balmy Saskatoon;)  where it worked in sub temperatures using just the heated expello valve. I trust the addition of an air dryer will be an improvement.

Actually using the unit with the ping tank will make the lines from the compressor easier to place, and the run back to the firewall connection will be straight shots.

I was just fighting with myself thinking  " Less is More "  meaning entering more things to make trouble later, but the benefits of the ping tank  likely wipe out much risk of that causing problems.

[bevans6]

The thing about the heated valve is that while the heated expello valve is keeping that guy nice and toasty, it won't do a thing for the valve on the air dryer which needs it's  own heater.  That's if you drive in freezing or near freezing temps.  That reminds me of a tip from Bus Warrior - it's good practice to arrange things so that you turn the bus off while the compressor is on a compression cycle, that ensures that the purge valve is closed so if it does freeze up over night it's frozen closed and you aren't stuck with listening to the purge valve dump all your air while you are trying to get going in the morning...

The valve heater on my bus is set up so that if the in-bus OTR heater is on, the purge valve heater is on.  Something to consider, anyway.

Brian

[Paso One]

I have been practising that "tip " for years.  I ran air operate stuff in Winnipeg , you had to do that if you wanted to work the next Day   I never shut it off until after the  Psst  release. My truck also had a alcahol injector also.

That is a good tip to wire the air dryer heater into the OTR heat switch never thought about it, I would have wired it into the  "run"  no sense heating all the time  we do get summer.

Second thought the 2 weeks we got of summer the heat would be on all the time either way LOL.

Stop laughing Bob you were away.

[buswarrior]

You need a minimum length run of pipe between the compressor and an air drier to allow the heat of compression to dissipate.

6 feet minimum, see this Bendix document for everything you need to know, and then some:

http://www.bendixvrc.com/itemDisplay.asp?documentID=4453

Too close to the compressor will shorten the desiccant life by way of cooking.

Easy to loop a line around the compartment or fashion a coil to get the mileage needed.

happy coaching!
buswarrior

[thomasinnv]

on my mci the air dryer is located above the front axle.  fwiw.

[Dave5Cs]

Might want to check your numbers , found this on a recall site,

Dave

AD-2 AIR DRYERS MANUFACTURED BETWEEN NOVEMBER 7, 2001, AND MAY 28, 2002. ORIGINAL EQUIPMENT PART NOS. 288595 AND 289008 AND AFTERMARKET SERVICE PART NOS. 102351, 102595, 103090, 103228, 286930, 286934, 288595, AND 289008. THE AIR DRYER CANISTERS CAN CRACK UNDER HIGH PRESSURES CAUSING THE METAL END PLATE TO BECOME DISLODGED AND EXPELLED WITH HIGH FORCE.

[Paso One]

Thanks for the link to the manual BW 

I'll Check my serial #'s Dave you never know, however this came from a recondition transit bus

Interesting that the dryer on your MCI is way up front negates the 6 foot rule 

[buswarrior]

6 foot MINIMUM piping, more is better, less is BAD.

MCI always had long desiccant life with the long run to the front, and no need for wandering piping in the back.

Like so many things, heat shortens the service life.

happy coaching!
buswarrior

[luvrbus]

Someone needs to educate me on the recall of the AD-2 dryer those haven't been made in over 20 years 



good luck

[Paso One]

Okay now  I have a very interesting observation, if you compare the pictures above, to the Bendix manual link that
Buswarrier posted.

Both those dryers were plumbed wrong.

The picture on page two of the manual clearly marks the "inlet " as the lower of the two ports.

Comparing that picture with the dryer picture I posted, shows the line coming from the compressor going into the ping tank then to the top port of the dryer.

The other picture posted shows the line coming from the compressor going directly to the top port on the dryer.

I can't believe that both dryers could have been plumbed incorrectly,  unless this is some kind of modification.

My installation has the line on a downward slope from the compressor ( recomended )  ultamately going into the inlet port indicated in the manual.

The line clearly marked "outlet" ( top port )  heading to the wet tank as originally designed.

If you think how the dryer works drying the air ( as discribed in manual ) it may not be a issue as as long as the unit is mounted straight up and down. the water gathers and is ejected out the bottom.

Just out of curiosity check your dryer  to see where the inlet port is located.

Thanks

[bevans6]

I do believe you are correct!  or the ping tank is between the air dryer and the wet tank for some reason.

Brian