Air dryer replacement fail

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Air dryer replacement fail

September 14, 2023, 12:19:21 pm

My air dryer is overdue for replacement. The current one is a PURest N4253AA, I got a replacement from NAPA, DA33100X.
After I installed it, no air was getting into the air system!!! I double, triple checked that I had reconnected all of the lines correctly.
I called Haldex customer service and told the tech what my problem was, and he quickly said I must have installed the wrong air dryer! I pulled the new dryer and contacted NAPA and they said I should have installed a DA34100, but they do not carry that model!!! I have searched the internet for one, with no success!
I reinstalled the original dryer, but my air system won't charge now!!!
I called Haldex and spoke to the same tech and he would only read a notice stating they don't support non licensed facilities!
Any assistance troubleshooting and getting my air system working again would be greatly appreciated!

Re: Air dryer replacement fail

Reply #1 – September 14, 2023, 01:11:35 pm

Think your best bet is to rebuild your original dryer,if it was working when you took it off,it should work now,are you sure it is installed correctly.

Re: Air dryer replacement fail

Reply #2 – September 14, 2023, 01:15:51 pm

You have to be careful when replacing one dryer model with another model. There may be compatibility issues with different Cummins engine air compressors so that is one factor. In addition, some air dryers require a external isolation valve, while other models do not. I cannot advise you on what model to use - my coach uses a different dryer setup.

Read through the threads linked below to see if you find any helpful info.

Minor oil leaks, should I worry?

Replacing Air Dryer problems

Air Dryer comparison

Re: Air dryer replacement fail

Reply #3 – September 14, 2023, 02:38:33 pm

John, I agree with your advice, rebuilding the dryer looks like the way to go!
I am concerned that reinstalling the original dryer didn't fix my problem, I am certain it's hooked up correctly. I took plenty of pictures and that's the only way the hoses would fit.
I reviewed the links Chuck sent, and determined I have a Holset E-Type compressor by the blue tag on my compressor. I'll need an external isolation valve.
Reading the "Air Dryer Comparison" link, Mike, (Pamela and Mike), mentioned these rebuild kits: DQ6026 & DQ6020 and isolation valve KN23500.

Thank you for your assistance,
Charlie

Re: Air dryer replacement fail

Reply #4 – September 14, 2023, 03:20:57 pm

Quote from: Want2rv – September 14, 2023, 12:19:21 pm

I reinstalled the original dryer, but my air system won't charge now!!!

I'm just trying some armchair diagnostics here, so take it for what it is worth...

You started out with a working dryer, removed it, replaced it with a different model. Then you removed the replacement dryer, and reinstalled the first dryer that was working. It is logical to assume that with the first dryer back in place your air system should work normally, but it does not. Why?

There are 3 primary components in the air system: the engine air compressor, the air dryer, and the D2 governor.

The engine air compressor has two operational modes - "loaded" and "unloaded". When the compressor is "loaded" it is sending air to the air dryer. When it is "unloaded" it is just kinda free wheeling - it is turning but not sending air to the dryer. So that is one thing to check: is the air compressor putting out air flow? I've never tried it, but with the engine running I would think you could feel this air flow coming out of the big hose that goes from air compressor to the dryer.

If the compressor is sending air to the dryer, then in order for system air pressure to build, the purge valve on the bottom of the dryer must be closed. If it is stuck open, you'll never get any pressure in the system. If, with engine running, you can feel air blowing continuously out the bottom of the dryer, then a stuck purge valve is the problem. The fix is to replace or rebuild the valve assembly.

If the engine air compressor and the dryer are working properly, you STILL need a properly functioning D2 governor to control the air system operation. The D2 tells the air compressor when to load and unload, and it tells the dryer when to purge. If your D2 is not "fresh" I would try installing a new or rebuilt unit. They are inexpensive and available at any NAPA store and most truck parts store counters.

http://www.plazafleetparts.com/uploads/2/1/9/0/2190100/d-2_governor_maintenance.pdf

Let us know if you make any progress trouble shooting your problem.

Re: Air dryer replacement fail

Reply #5 – September 14, 2023, 03:35:02 pm

Do what Chuck said and get back to us,in the meantime get the kits coming,check Ebay also and get
A D2 coming,to rebuild the drier the best way is to remove it and put in a vise.

Re: Air dryer replacement fail

Reply #6 – September 14, 2023, 03:35:49 pm

Have you checked the air line coming from your compressor to see if you have air coming
from the compressor. It could be your governor decided to quit.

Re: Air dryer replacement fail

Reply #7 – September 16, 2023, 08:58:59 am

No air is coming to the high pressure line at the dryer.
I just got a replacement D2 and will install it!!
I'd cross my fingers, but it's hard to do so and turn a wrench!!

Re: Air dryer replacement fail

Reply #8 – September 16, 2023, 10:02:06 am

After installing the new D2 governor, there is still no air at the high pressure in-line at the dryer!
I guess it's time to search for compressor unloader valve troubleshooting.

Re: Air dryer replacement fail

Reply #9 – September 16, 2023, 10:41:14 am

Could the problem be associated with the isolation valve??
That valve is part of the last place I was working, and it wouldn't be the first time I've been guilty of damaging a working system!

Re: Air dryer replacement fail

Reply #10 – September 16, 2023, 11:26:12 am

Quote from: Want2rv – September 16, 2023, 10:41:14 am

Could the problem be associated with the isolation valve??

Highly unlikely. The isolation valve is very simple inside - just a sliding piston and seat. It does not have any "control" function over the air compressor - it simply closes off the air pressure line from the compressor to the air dryer when the D2 tells the compressor to unload. Since your D2 is now fresh, I would guess the unloader device in your air compressor is the next logical suspect to investigate.

Air Dryer: Haldex Isolation Valve - All Things Foretravel

Air Compressor - All Things Foretravel

Troubleshooting Charging & Air Supply Systems [ForeForums Foretravel Wiki]

Re: Air dryer replacement fail

Reply #11 – September 16, 2023, 11:43:42 am

Quote from: Want2rv – September 16, 2023, 10:02:06 am

I guess it's time to search for compressor loader valve troubleshooting.

The unloader device in the air compressor should fail (default) to the loaded compressor mode. IE, if there is no signal being sent to the unloader from the D2 governor, the air compressor should be pumping air. If it is not pumping air, good possibility that the unloader valve is stuck in the "unload" position. You could try tapping on the unloader with a hammer to see if it frees up.

Link to previous Forum discussion of the Holset E-type unloader mechanism:

Can't build air, not the D2 governor

Page below from a parts catalog:

Air Compressor Unloader and Valve Assembly

Document linked below may be of some interest. Scroll through the whole document to see if anything matches your engine setup.

https://www.dtnaecomponents.com/DTNAHardwareComponents/Freightliner/BusinessClassTrucks/BusinessClassTrucksServiceManual/BusinessClassTrucksServiceManualGroup13AirCompressor.pdf

Re: Air dryer replacement fail

Reply #12 – September 16, 2023, 03:13:37 pm

I love when a hammer fixes a problem!!!!
Wish I tried it first!
I got it to 125 lbs!
Thank you all for your suggestions and support!!
Let's hope rebuilding the air dryer goes smoother!

Re: Air dryer replacement fail

Reply #13 – September 16, 2023, 03:52:07 pm

Quote from: Want2rv – September 16, 2023, 03:13:37 pm

I love when a hammer fixes a problem!!!!

Happy it worked, but be aware that you didn't fix the problem...you simply treated the symptom.

If the unloader mechanism is getting gunky inside, it's just a matter of time before this happens again. The CURE is to either:
1. Disassemble the unloader, clean it up, and perhaps install a rebuild kit.
OR
2. Install a complete new unloader module.

Re: Air dryer replacement fail

Reply #14 – September 16, 2023, 04:21:36 pm

Good advise!!!
It will be done!
Thanks

Re: Air dryer replacement fail

Reply #15 – September 19, 2023, 01:29:15 pm

There is also the possibility that it got stuck open due to the wrong Air dryer being in place and that with a newly rebuilt proper air dryer that won't happen again.
For proper safe sleeping and peace of mind you might want to just replace it anyway.
Curious how many times did you have to hit it with a hammer before it closed?

Re: Air dryer replacement fail

Reply #16 – September 19, 2023, 03:49:27 pm

Good point, since it was working before the swap!
I tapped it 6 or so times, it wasn't easy getting a clean tap due to the location!!
Servicing it won't be fun!!!

Re: Air dryer replacement fail

Reply #17 – September 20, 2023, 09:34:20 am

Spray a little wd40 into the inlet of the compressor. That will clean up the sliding valve .

Re: Air dryer replacement fail

Reply #18 – September 20, 2023, 11:05:27 am

I used Corrosion X to free up the one on my crane 8 years ago, still working.

Re: Air dryer replacement fail

Reply #19 – September 22, 2023, 09:50:54 pm

Okay. Dumb question. I'm having air problems as well and suspect the compressor. How do you spray something into the inlet of the compressor?

Re: Air dryer replacement fail

Reply #20 – September 23, 2023, 11:00:03 pm

Post a picture of your compressor and the lines going to and from it. The line that doesn't go to the dryer is the inlet.

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