Changeing the Haldex Air Dryer Cartridge

[James]

I'm thinking about changing the desiccant cartridge in the Haldex AT-87192 air dryer.

The last coach we had I was able to replace the cartridge without draining any of the air lines or tanks.

In reviewing the Haldex maintenance information that came with the bus I noticed that it states "Drain all reservoirs and air lines to 0 psi." prior to servicing.

Anyone have experience with the AT-87192? Is it necessary to drain all air to 0?

[JIM CHALOUPKA]

Well the thing is, your going to be down there so you might as well open your tanks and drain them and get it all done at the same time.

You must drain the tanks to zero pressure to get the water out, just some short blasts will not do it

Not sure how it has been for others but when working from your back on the ground you will need the special wrench in the proper size (large) for the canister/cartridge whatever.

I was able to get both from a NAPA. If you have AAA for your auto most NAPA's extend a discount.

Good luck, mine was very tight, needed a 20" breaker bar

JIM

[Jon Wehrenberg]

James, I assume you mean the spin on cartridge and it is located ahead of the drive axle, up high on the passenger side.

Jim C is correct in that part of the air system maintenance should include draining all the tanks. To verify the protection valves are working, start at the front and move to the rear. Each tank in line should contain air pressure if the protection valves are functioning properly, as as Jim correctly points out the tank must have zero pressure to assure all trapped moisture is out. If you start draining the air coming out literally blows a hole through the moisture and it is only when the air is depleted that the balance of the water/oil comes out.

You can remove the spin on air dryer element without dropping the bus air pressure to zero, but why? You need to drain the tanks anyway.

The filter in my opinion like Jim's is a bitch to get started. I use a rubber strap filter wrench with the greatest success and I can tell you from changing about 6 now (spin on) that strong steady pressure while standing with your feet locked tight to something will get the job done. I have done it from my pit and while sitting in the wheel well area without a pit and while sitting you exert enough force to literally slide your butt across the floor. Stand if you can.

When putting the new spin on cartridge on I use white grease on the gasket and each time I spin it on less and less tight trying to find the exact point at which it seals, but doesn't cause me to bust a gut trying to get it off. So far it has required a lot of force. I change mine every two years.

[James]

Great advice but this is not your regular Bendix spin on cartridge. The Haldex cartridge is inside an assembly held on by 4 15mm bolts torqued to 35-40 ft lbs.

However, as far as the air system maintaining pressure, I would think you should be able to remove the assembly without draining the system.

Of course draining the air is never wrong, I was just wondering if it was a requirement with the Haldex.

[JIM CHALOUPKA]

In reviewing the Haldex maintenance information that came with the bus I noticed that it states "Drain all reservoirs and air lines to 0 psi." prior to servicing.


Can't help you in that regard. I do think it would be best to follow the manufacturers directions. They wouldn't bother telling you to go to zero if it weren't necessary.

[JIM CHALOUPKA]

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