Can anyone help me identify this air dryer please? I'd like to replace the whole shebang but the sticker has warn off and I can't find a stamped part #
I believe Pierce had one like that and changed it for the spin-on type.
I'm guessing it is a Bendix AD-4. If so, it can be replaced with the AD-9. This is what happened on our coach sometime in the misty past. The (factory rebuilt) AD-9 is readily available from most any NAPA store.
BENDIX AD-4 AIR DRYER MANUAL Pdf Download | ManualsLib (https://www.manualslib.com/manual/392579/Bendix-Ad-4-Air-Dryer.html)
If you do the swap, you may need the external isolation valve...depends on what air compressor is fitted to your engine. See thread linked below:
How to update Bendix AD4 to AD9 on 91 GV U300 (https://www.foreforums.com/index.php?topic=42165)
Chuck just so I'm clear, it is possible for me to have an AD4 without an isolation valve, and when I convert to an AD9 I may need to add that isolation valve?
Or is it safe to assume that I do not need an isolation valve on the AD9 if I do not currently have one?
Can't answer your questions Elliott, but you might want to change out that duck dill drain on the bottom of your air filter housing, especially if it's original.
When talking about old coaches that have been "cared for" by multiple owners, I don't think it is safe to assume anything you find is necessarily "correct".
If I were you, I would first determine what air compressor is mounted on your engine. Some compressors, when paired with some dryers, will require a isolation valve - other combos do not.
Then I would decide what air dryer you want to install. Have you looked into the availability of rebuilt AD-4 dryers? They might be pretty scarce...I have no idea. The AD-9 dryer does not
always require the isolation valve - it depends on the air compressor model. And, as Chuck mentioned in Reply #1, there are other dryers that might be an even better upgrade.
Once you know exactly what air compressor you have, and what dryer you are going to install, then you can look up that combo to see if it requires the external isolation valve. It might take a little research on your part, but in the end you will be confident that you have the correct setup. Much better than relying on the technical expertise of whomever installed the last dryer on your coach.
You might have already seen these videos. If not, they discuss the air compressor/air dryer relationship.
https://www.youtube.com/watch?v=EAZJuaX1xNM
https://www.youtube.com/watch?v=LjWQStJxXf8
Hey @Chuck & Jeannie how do I determine if my compressor needs an isolation valve or not? I have a Bendix Tu-Flow 501 compressor and am not seeing any mention of one in the 501 literature: https://n0c357rmy1njbuit2friqwu.blob.core.windows.net/documents/h$YJunINI0EBhB_SD-01-337_US_000.pdf
On a related note: current plan of attack is to go with an AD9 for the replacement but I'm open to other dryers if someone has a strong suggestion.
Good question.
Our '93 U280 has the AD9 air dryer and it is fitted with an isolation valve - but we have a different air compressor.
You need to talk to a expert, and that's not me by any measure.
Did you watch those videos I linked in a earlier reply? That looks like a guy who knows about this stuff.
Those videos are put out by Fleet Products Ltd.
I went to the company website, and searched Tru-Flo 501 compressor. Got lots of hits, so they are familiar with that compressor.
I would suggest trying to call that company. Tell them what air compressor you have and ask about using the AD9 dryer.
I'm betting one of their tech guys will be able to answer your question about the isolation valve and if it is needed.
Haldex Isolation Valve (https://web.archive.org/web/20200111052240/http://beamalarm.com/Documents/haldex_isolation_valve.html)
https://www.youtube.com/@fleetproducts/videos
Air Brake Compressors - Fleet Products (https://www.fleet-products.ca/categories/Air-Compressors/)
TF-501 Cummins (286555X) - Air Brake Compressor (https://www.fleet-products.ca/286555x-tf-501-cummins-compressor/)
How does an isolation valve differ from an inline check valve ?
I changed my ad 9 to a newer spin on type. The AD9 dried the air better but I can swap the cartridge every 6 months easy now.
Mike what dryer did you go to? I too would prefer a spin-on type. And do you by chance know which compressor you have?
Chuck I did watch those videos when you first shared them, very insightful.
4324210337 Air Dryer for Volvo, Freightliner, Kenworth, Western Star Trucks... (https://www.ebay.com/itm/325762651731?hash=item4bd8f79653:g:v90AAOSwVb5k0I8V&amdata=enc%3AAQAIAAAA8OhIhvtQhYkEvMR1yq6sW4UR6PDDgZ5P7pIEAusiiXOJe6b20MYcBRlTuRG3GP2mSDZZvYiTpB%2BGPtJMHH%2BZmEmOXFjLQ6s5v12ufQepgC4TT%2FYJyXqiN3d5rmO%2BXOZjHBpa2Tu06wnVawl%2BlJbvUbccYspmYLkk1%2FPrWcgtoNhAYB2CwC9Nkgpe8MNn2G8KKDOz%2FHcvwBuLW1yXfi1K5%2BkmgPFdjYZzjbstr%2FCaDbhID1XAR4lydb%2BW4scdOMVl8R9PNhIyTAwMZGbIJnOgKk81dipSd3GBRmgzqtyre5sIFWQBI9dpNCSPbeD%2FClQ17A%3D%3D%7Ctkp%3ABk9SR47U-7noYg)
The huge AD9 works better but can get tied up for parts . My compressor is a 501. I just serviced the unloader valve and replaced al of the check valves that I could find. Both tank inlets , etc.