help identifying air dryer

[RS Disposal]

I am wanting to service my air dryer being I can't find in maintenance records my dad had for the truck when it or if it was last done.  I can't find a tag on the dryer or and specific info on it in the factory service manual. Not sure if I can actually get it apart being truck sees ALOT of road salt in the winter.  If that is the case what style of air dryer should I be looking at.  A google search shows there are quite a number of different dryers available.

[Geoff Weeks]

AD-2 extended purge from the look of how tall it is, unless that it just a trick of the picture. Anyway you cut it, it is an AD-2.

Edit: Looking more closely, I think it is a regular AD-2 just the angle of the shot made it look taller.

Edited 5 hours ago by Geoff Weeks

[Geoff Weeks]

Here is Lit on it.

Bendix AD-2.pdf

[Geoff Weeks]

AD-2's are still around because they fit where many other style will not. Tall and skinny.  Parts and rebuilt end covers are still available. Be advised, the end covers are made in both 12 volt and 24 volt models. The voltage is for the internal heater that keeps the valves from freezing up in cold weather. 

Replacement desiccant cartridges are also available. I would not disassemble the cartridge as I doubt you can get replacement beads. You just buy a whole rebuilt cartridge. 

[RS Disposal]

1 hour ago, Geoff Weeks said:

AD-2 extended purge from the look of how tall it is, unless that it just a trick of the picture. Anyway you cut it, it is an AD-2.

Edit: Looking more closely, I think it is a regular AD-2 just the angle of the shot made it look taller.

the air dryer is fairly tall as compared to what I have seen on other trucks.  Plenty of room whereas the dryer is on the inside of the frame rail and nothing else around it

[Geoff Weeks]

The hose from the compressor (in to the bottom of the drier) looks like it is well past its "use by" date! I'd be replacing that before I did anything else. That looks like it is about to pop and likely is already leaking badly.

Yes, the AD-2 is much taller and skinny when compared to new ones.  I'd fix what you have, the AD-2 and AD-4 work well but are less "user friendly" when it comes to service, never the less, will outlast just about all the newer ones. really all the hoses connected to the drier look bad.

Edited 3 hours ago by Geoff Weeks

[Geoff Weeks]

What problems are you noticing? My guess it you're hearing it pop-off frequently? That is not the drier but the air system. Replace the hoses going to the drier and see if that doesn't cure most of what you are hearing.

[RS Disposal]

30 minutes ago, Geoff Weeks said:

The hose from the compressor (in to the bottom of the drier) looks like it is well past its "use by" date! I'd be replacing that before I did anything else. That looks like it is about to pop and likely is already leaking badly.

Yes, the AD-2 is much taller and skinny when compared to new ones.  I'd fix what you have, the AD-2 and AD-4 work well but are less "user friendly" when it comes to service, never the less, will outlast just about all the newer ones. really all the hoses connected to the drier look bad.

i am working on replacing most of the lines one by one on this truck being it is a 1979.  I know rubber breaks down just from age (not alot of miles but 47 yrs old) and this truck has seen alot of road salt.  The problem I am having is that once it got cold the truck had a hard time building air.  I replaced the governor which seemed to help a bit.  Air pump was replaced about 5 or 6 years ago. Being a garbage truck it does alot of start and stopping.

[Geoff Weeks]

The vast majority of the time when a vehicle has trouble "building" air, the problem is it is having trouble holding on to the air that has been compressed into the system.

A system that has a true "building air" problem, will hold the air just fine after the cut-out pressure is reached, it will hold at 120 psi with the compressor unloaded for a long time.

Much more common is for the system to rapidly loose pressure, start compressing again, then loose it once the compressor unloads.

Check for air leaking out of the purge valve on the bottom of the drier when the compressor is active. You should get a burst of air followed by a slow release of air out the purge valve when the compressor unloads.

 A leaky air line between compressor and drier will act the same. A leak after the drier will cause rapid cycling of the compressor.

[RS Disposal]

35 minutes ago, Geoff Weeks said:

The vast majority of the time when a vehicle has trouble "building" air, the problem is it is having trouble holding on to the air that has been compressed into the system.

A system that has a true "building air" problem, will hold the air just fine after the cut-out pressure is reached, it will hold at 120 psi with the compressor unloaded for a long time.

Much more common is for the system to rapidly loose pressure, start compressing again, then loose it once the compressor unloads.

Check for air leaking out of the purge valve on the bottom of the drier when the compressor is active. You should get a burst of air followed by a slow release of air out the purge valve when the compressor unloads.

 A leaky air line between compressor and drier will act the same. A leak after the drier will cause rapid cycling of the compressor.

lately I haven't been getting anything out of the purge valve when the system reaches 120.  I agree that the line between compressor and dryer should be replaced.  It is definitely on the list of things to do with this truck. Right now I am also fight a fuel problem which I am hoping is old/bad fuel lines. The truck was never maintained as it should of been when my dad was operating the business and then sat for 20 yrs before I opted to put it back into service

[Joey Mack]

GW ?  What do you think about ditching that old one and installing either an AD-6 or an ADIP model. I prefer the AD-6..

[Geoff Weeks]

I doubt the AD-2 is the problem. I have one that is still going fine. I'd put my money into replacing hoses before I touched the air drier.

When I scrap the Fleetstar with the AD-2, it is going on my K-7, only drier that will fit behind the cab under the body.

I took off all newer driers (AD-9 and Rockwell/Meritor) and installed AD-4's. Even converted some AD-9's into AD-4's with the addition of a plate and base.

The older driers are a pain to service compared to a "spin on" or single bolt (AD-9) but will out last them hands down. 

If you take care of the air system, so it is not popping off all the time, an air drier will go years perhaps decades without being serviced (yes, I know decades is not recommended). When you start to see moisture out of the wet tank, then look at the air drier, if the rest of the system is up to snuff.  

[Joey Mack]

The AD-6 is a spin on. I use my Cat oil filter tool to replace them.  To me, very easy to maintain..  all good..

[Geoff Weeks]

Never heard of one, and the internet doesn't return any hits. is a AD-IS? that take a spin-on cartridge. there is AD-SP which is Bendix version of the Meritor spin-on and requires purge air from the secondary air tank. 

The early air driers have internal purge volume, so don't need extra tanks or a SC-PR valve (a check valve that allow a set amount of air back to purge the drier. 

With air start trucks, I wanted to make sure my air was dry. The AD-4 did that for me and didn't need a lot of baby sitting. I had 2 AD-9's fail, and I swore I wouldn't have another. One the threads in the base failed, the other the outlet check failed.

[Joey Mack]

🤔

[Geoff Weeks]

Turns out desiccant for the AD-2 is available:

AD-2 desiccant

 

[Joey Mack]

I see the AD-IS..  thats like the one I was suggesting. The one I called an AD-6.   I dont think I made up that unit number, however..... who knows ? 😄

[Geoff Weeks]

Ah grasshopper, special air drier made for Mack mechanic, not for IHC man!😄

[Mark T]

50 minutes ago, Joey Mack said:

I see the AD-IS..  thats like the one I was suggesting. The one I called an AD-6.   I dont think I made up that unit number, however..... who knows ? 😄

🧐