Changing the Air Dryer FIlter

[Dutch Star Don]

A couple of people asked me to post if I did the air dryer filter replacement.

I've been dreading changing the Air Dryer Filter because it's soooooo hard to access. Freightliner wanted $400.00 in labor to do the job. I started and stopped the job a couple of times today, as I just couldn't see how I could get to it. There is large (nut) hose that has to be removed and very hard to access. If I couldn't get it loose, I was done. Luckily it came loose easily.

The Bendix Air Dryer unit is mounted to the driver's frame rail, between the rear tire and tag. I ran my coach up on 6" ramps and then put blocks under the jacks. I dumped the air and drained the tanks. I extended the jacks to give me working room, but the ramps lifted the coach high enough if the jacks failed.

The Air Dryer is bolted to a bracket that is then bolted to the frame. It's also clamped at the top with a metal band. Unless the project was done over a pit or on a lift, there is no way to even reach or release the clamp at the top.

In the attached photo, you can see the metal bracket that is attached to the bottom of the air dryer. I'm pointing at the first two bolts that need to be removed, to release the air dryer assembly from the frame/bracket. The only way I was going to be able to remove the filter was to drop the air dryer assembly by moving this bracket out of the way, leaving the can still attached at the top.

Before you do any of this, there are four connections to the unit. One of the connections is a large nut (1 1/4") that takes an actual large open end to loosen, a crescent won't fit. Loosen and remove this line, unplug the quick connect sensor and then unplug two more air hoses. They're the quick connect type, where you push in on the ring and pull the hose out.

Once the hoses are removed, you need to remove two of the eight 9/16" nut/bolts that hold the filter cover on and are bolted through the support bracket. Once those are removed, you can work on the two 9/16" nut/bolts that hold the bracket to the frame. These bolts were the toughest to remove of the entire project. It was tough to access the nut on the back side, but is doable. I only removed one and loosened the other. Once one is removed, the bracket can be swung down and out of the way. You'll be glad you don't have to remove both.

Now it gets easier, there are eight 9/16" nut/bolts that hold the air dryer to the filter cover. You've already removed two. Remove five more, leaving the easiest one to access for last. Once you're down to the last one, the air dryer assembly and filter will drop out as you remove the last bolt. All eight nut/bolts had two washers each.

I took the unit out and put it on my bench. You'll most likely need a vise to hold the base as the filter is very tight. I was able to use a large pair of vise grips to spin the filter off. Once it off, there are two O-rings, one under the cartridge and one around the outer edge of the canister. The replacement unit comes with the two new O-rings and grease to lube the O-rings.

Once the new cartridge was installed in the air dryer base, I reversed the removal procedure.

I will tell you that this not a project for the faint of heart. It's a dirty project because the air dryer is in line with the rear u-joint and grease gets thrown on the air dryer. This job is not highly technical, just dirty with one hard to reach nut/bolt that holds the bracket to the frame.

[Mr_D]

I just don't understand why they make them so hard to get to! Mine is above the tag axle, the dealers service dept said they changed it as part of their PDI. And at least the date on the filter shows it was done.

[Dutch Star Don]

My Diplomat had a spin on Wabco filter in a bay. Five minutes max and I was done. This was just idiotic. It wont need changing again for another four years, at which time I'll be 65 and either too old to do it, or driving another coach.

[C.Martin]

Wow...that does NOT sound like a lot of fun.

I was really hoping I could get purchase on the filter with a strap wrench...drain air from tanks...and just spin it off.

I admit....I have never even glanced up to see how impossible they make this job. All the Freightliner techs standing around a Chassis at Rallys say to drop the whole assembly, like you did.

It is not a project I am looking forward to.

[Dav L]

I usually start these projects with:
Step 1, jack it up
Step 2, block it up
Step 3, power wash the grit off
Step 4, wait for it to dry off
Step 5, rest of procedure.

My 2002 this is super easy access. Dryer is attached to a bracket at the rear most portion of the frame rail, behind the motor. Might take 5 minutes. Bleed air, Spin off, spin on, start it up.

[Algoma]

Thanks for doing that Don.
On my previous Alpine Coach I also had to remove the whole unit and change the desiccant at the bench, but at least it was accessible. I noticed that on the Spartan chassis it is mounted at the rear close to other filters, which would affect my choice if I were looking at a Dutch Star in the future.

[Old Scout]

.....Ref John's comments on Alpines, agree, access wasn't an issue but getting the cartridge off the Bendix dryer assembly was. Finally removed dryer from frame, made a jig out of plywood to hold dry assembly in place, fashioned a heavy duty strap wrench out of cargo strap and a cheater bar--only then did I get the cartridge loose----ugly!!!!

[turbopilot]

Originally Posted by Dutch Star Don

A couple of people asked me to post if I did the air dryer filter replacement.

Thanks for documenting your experience. This is what makes forums like this work.

[twojayhawks]

My hat is off to you Don & others that can do this kind of work. I actually just had my dryer element changed two weeks ago & tech chose to drop the drive shaft??? I'll have to let him know you were able to get it done without having to do so.

[Mr_D]

Originally Posted by Dutch Star Don

My Diplomat had a spin on Wabco filter in a bay. Five minutes max and I was done. This was just idiotic. It wont need changing again for another four years, at which time I'll be 65 and either too old to do it, or driving another coach.

At 65 you're not too old to do it. I'm 71 now and should do it next year as that'll be four years on it.
Driving another coach after all you've done to this one? I'll believe that when I see it!!

[Algoma]

Originally Posted by Mr_D

At 65 you're not too old to do it. I'm 71 now and should do it next year as that'll be four years on it.

I guess it depends if we are talking about years or inches around the waist

[jerry davis]

Originally Posted by Dutch Star Don

A couple of people asked me to post if I did the air dryer filter replacement.

I've been dreading changing the Air Dryer Filter because it's soooooo hard to access. Freightliner wanted $400.00 in labor to do the job. I started and stopped the job a couple of times today, as I just couldn't see how I could get to it. There is large (nut) hose that has to be removed and very hard to access. If I couldn't get it loose, I was done. Luckily it came loose easily.

The Bendix Air Dryer unit is mounted to the driver's frame rail, between the rear tire and tag. I ran my coach up on 6" ramps and then put blocks under the jacks. I dumped the air and drained the tanks. I extended the jacks to give me working room, but the ramps lifted the coach high enough if the jacks failed.

The Air Dryer is bolted to a bracket that is then bolted to the frame. It's also clamped at the top with a metal band. Unless the project was done over a pit or on a lift, there is no way to even reach or release the clamp at the top.

In the attached photo, you can see the metal bracket that is attached to the bottom of the air dryer. I'm pointing at the first two bolts that need to be removed, to release the air dryer assembly from the frame/bracket. The only way I was going to be able to remove the filter was to drop the air dryer assembly by moving this bracket out of the way, leaving the can still attached at the top.

Before you do any of this, there are four connections to the unit. One of the connections is a large nut (1 1/4") that takes an actual large open end to loosen, a crescent won't fit. Loosen and remove this line, unplug the quick connect sensor and then unplug two more air hoses. They're the quick connect type, where you push in on the ring and pull the hose out.

Once the hoses are removed, you need to remove two of the eight 9/16" nut/bolts that hold the filter cover on and are bolted through the support bracket. Once those are removed, you can work on the two 9/16" nut/bolts that hold the bracket to the frame. These bolts were the toughest to remove of the entire project. It was tough to access the nut on the back side, but is doable. I only removed one and loosened the other. Once one is removed, the bracket can be swung down and out of the way. You'll be glad you don't have to remove both.

Now it gets easier, there are eight 9/16" nut/bolts that hold the air dryer to the filter cover. You've already removed two. Remove five more, leaving the easiest one to access for last. Once you're down to the last one, the air dryer assembly and filter will drop out as you remove the last bolt. All eight nut/bolts had two washers each.

I took the unit out and put it on my bench. You'll most likely need a vise to hold the base as the filter is very tight. I was able to use a large pair of vise grips to spin the filter off. Once it off, there are two O-rings, one under the cartridge and one around the outer edge of the canister. The replacement unit comes with the two new O-rings and grease to lube the O-rings.

Once the new cartridge was installed in the air dryer base, I reversed the removal procedure.

I will tell you that this not a project for the faint of heart. It's a dirty project because the air dryer is in line with the rear u-joint and grease gets thrown on the air dryer. This job is not highly technical, just dirty with one hard to reach nut/bolt that holds the bracket to the frame.

Attachment 198682

Don,
We’re you able to tell the condition of the old filter? Was it necessary to replace now or could you have gone longer? I know you live in a fairly dry climate.

[Algoma]

Originally Posted by jerry davis

Don,
We’re you able to tell the condition of the old filter? Was it necessary to replace now or could you have gone longer? I know you live in a fairly dry climate.

In my experience, you can only tell if the desiccant is no longer doing it's job when you start getting water from the air tanks when you purge them. This is often caused by oil contamination from the air compressor. Without contamination the desiccant could probably go for 10 years without a problem.
So, like most service items, changing the desiccant at 4 years is preventative maintenance.

[Stretch]

Originally Posted by Algoma

In my experience, you can only tell if the desiccant is no longer doing it's job when you start getting water from the air tanks when you purge them. This is often caused by oil contamination from the air compressor. Without contamination the desiccant could probably go for 10 years without a problem.
So, like most service items, changing the desiccant at 4 years is preventative maintenance.

Looked like hard work Don. On our last coach a 2005 HR Navigator which we had until last year, I kept looking at the dryer but didn’t touch it . I checked the air tanks but they were always dry. So I never bothered. Just hated to get this 79 year old body in a position I couldn’t get out of. Never gonna attempt it on our “17” Dutch Star 4369