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Re: Air Dryer Bypass Demo

Reply #80 –
I replaced ours last year with a spin-on with heater/etc. It was the OEM with 100,000 miles but seemed to be working fine. Just figured it was time. The spin-on changes in a couple of minutes.

Pierce

Re: Air Dryer Bypass Demo

Reply #82 –
I called Bendix today and talked to a Tech Person and asked how often my AD9 Dryer needed servicing. His answer was all applications are different. But he said when you change one keep track of how long until you start seeing an accumulation of water discharge from wet tank when you drain it. Then back it up a month and change at that interval. I asked about a suitable replacement with a spin on filter and he recommended one But it has the air governor built into it and I would not use the Governor on the compressor D2. I don't  think I want to change D2 are cheap and easy to replace when needed. Having governor built into dryer to me might not be as easy to service.They always crap out at the worst time and place. I have been getting water out of my wet tank every couple weeks but the only compressor running is the 110 volt that occasionally  comes on to refill air bags. Does that air go through wet tank? I guess I need to pull out coach books when I get back off the road.

Re: Air Dryer Bypass Demo

Reply #83 –
Quote from: propman –
Which brand, SP?
Thank you,
AL
Think most of the aftermarkets are made in Poland by the same company. Germany is the original. I purchased ours from National Drivetrain for about $90-100 delivered. Quality looks excellent. Make sure to loosen and then tighten the spin-on once you have it installed as they are really stiff. I did need to buy a couple of inexpensive fittings. Make sure the hydraulic hoses do not touch each other after installation or they will fray and fail. AIR DRYER ASSEMBLY - REPLACES MERITOR WABCO SYSTEM SAVER 1200 SERIES R955205...

I modified the old bracket and then did a really quick powercoat on it. Buy a crow's foot before starting.  Here is the link to the Google album showing the installation and crow's foot. Wabco-Meritor 1200 Air Dryer U300 Installation - Google Photos

For owners with problems on the OEM dryer, make sure the power to the heating element is hot (12V).

Pierce

Re: Air Dryer Bypass Demo

Reply #84 –
Thanks Pierce,
 Changed out my D 2 today as it took a lot longer than normal for pressure to build.  Thought all was good , came home tonight, fired it up to build enough air to get the jacks under it and it still took  way too long. 
 Once up it holds air  for a few hours with no signs of leaks.
 Does this sound like the dryer  control line is suspect?   

Re: Air Dryer Bypass Demo

Reply #85 –
Quote from: stump –
I called Bendix today and talked to a Tech Person and asked how often my AD9 Dryer needed servicing. His answer was all applications are different. But he said when you change one keep track of how long until you start seeing an accumulation of water discharge from wet tank when you drain it. Then back it up a month and change at that interval. I asked about a suitable replacement with a spin on filter and he recommended one But it has the air governor built into it and I would not use the Governor on the compressor D2. I don't  think I want to change D2 are cheap and easy to replace when needed. Having governor built into dryer to me might not be as easy to service.They always crap out at the worst time and place. I have been getting water out of my wet tank every couple weeks but the only compressor running is the 110 volt that occasionally  comes on to refill air bags. Does that air go through wet tank? I guess I need to pull out coach books when I get back off the road.
I got a remanufactured AD9 for $155 with a $90 core charge, so only $65 to replace the whole setup. D2 was $15ish.

Re: Air Dryer Bypass Demo

Reply #86 –
Quote from: Protech Racing –
Thanks Pierce,
 Changed out my D 2 today as it took a lot longer than normal for pressure to build.  Thought all was good , came home tonight, fired it up to build enough air to get the jacks under it and it still took  way too long. 
 Once up it holds air  for a few hours with no signs of leaks.
 Does this sound like the dryer  control line is suspect?   
To figure it out, we need to find out where the pressure goes down to and how long it takes to get there after you shut down. If it's in the cycle range, it should build from 80 psi to 100-110 psi in a minute or so. If it's below, it could be an airbag leak or possibly related to the dryer. As I remember, once ours goes below 80 psi, it seems to take forever to come up. The tanks and bags take a lot of CFMs to get to the 80 psi mark.

First, I like to listen for leaks, then I bring out the small Hudson sprayer with soap or better yet, go to your local party store and get 8 oz of Pustefix. Bubbles don't pop and last a long time. Any leak anywhere will show up. Amazon.com: Pustefix Premium Bubbles Refill 8.3 fl.0z.: Toys & Games

OK, driving down the road, how often does your compressor cycle?

Pierce
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Re: Air Dryer Bypass Demo

Reply #87 –
The slow pressure  build is new . Last time out , 3 wks ago, pressure built in a few minutes at low idle to 100.  The build was linear all the way up.  Today it builds to 50 right away and then sits @ about 70 for  few minutes. 
  I listen well for leaks , found a small one at the dash vacuum motor that was not in use. Plugged it off.  The park handle has a very slight hiss some times but always has had it.  No loss when pushed in.  I sprayed the bags/ look old but sound and test tight.
 This morning ( getting to move the bus to high ground) air would  not go to 80.  New D2  built to 50 in a minute but took 5 min to get to 80 and then went quickly to 125 and stayed 125 .  Shut down air stayed about 100 for 5- 10 min and still showed 60 or more on the red needle  and 70 on the green needle after 6 hrs.

Re: Air Dryer Bypass Demo

Reply #88 –
I don't know if your air compressor is anything similar to the Bendix one on my crane, but I had unloader valves sticking causing a similar problem.

Re: Air Dryer Bypass Demo

Reply #89 –
Besides the unloader valve, you might take a look at the compressor head. Jerry Maddux recently overhauled his and is the expert here.

Pierce

Re: Air Dryer Bypass Demo

Reply #90 –
Or a sticking purge valve on the dryer, it's before the check valves so once tank pressures are up they tend to stay up and  it don't show up in a leak down test, same goes for any lines before the check valves.

Re: Air Dryer Bypass Demo

Reply #91 –
The unloader and purge valves are my suspects as I read more about how it works.  Pretty sure the compressor is good as it
 recovers,builds quickly  from  multiple brake  use. right back up to 120.
 Is there a way to block the purge valve  to check the rest?  Taptap  test?.
 
  BTW,  Thanks for the tips regarding the spare D2 in the bus , I would have been beached without it for sure . This forum has been a life/wallet saver..:) 

Re: Air Dryer Bypass Demo

Reply #92 –
Might be able to put some foil duct tape over the purge port and see if that helps to identify a leak

Re: Air Dryer Bypass Demo

Reply #94 –
I freed my unloader by spraying Corrosion X in the port from the governor. Hasn't stuck again going on 6 mo.

Re: Air Dryer Bypass Demo

Reply #95 –
Will try that .  Thanks,MM
Seems to help. Has built air 4 times solid .

Re: Air Dryer Bypass Demo

Reply #96 –
What happens when an air dryer fails...........does it become blocked that air won't pass through it?

If that's the case then why not incorporate a shut-off valve linking the two air lines (like an H pipe exhaust) anywhere before the dryer?  Then in the event of failure you should only have to just open the valve, and not get dirty.

Re: Air Dryer Bypass Demo

Reply #97 –
Worse, way worse

Desiccant is like fine talc and contaminants the valves in the HWH system.
Major $$$ and PITA

System doesn't stop working, but components do

Re: Air Dryer Bypass Demo

Reply #98 –
Quote from: Travelin' Man –
1.  What happens when an air dryer fails?

2.  Why not incorporate a shut-off valve linking the two air lines (like an H pipe exhaust) anywhere before the dryer?
1.  Search "air dryer failure" on this Forum.  You'll be treated to all the gory details!

2.  This has been discussed.  See Reply #3 and Reply #9 in this thread.

Re: Air Dryer Bypass Demo

Reply #99 –
I understand..................thanks guys.