Freightliner M2 air dryer.

[dlfishing]

I was told a story yesterday by an RV tech about brakes locking up because the filter hadn't been changed in the air filter and that it should be changed every couple of years in a motorhome.
Seems it's time to change mine in my 2014 DX3. Don't remember reading anything about that in my manuals.
Anyone familiar with this issue?

[Delco Bobby]

Originally Posted by dlfishing

I was told a story yesterday by an RV tech about brakes locking up because the filter hadn't been changed in the air filter and that it should be changed every couple of years in a motorhome.
Seems it's time to change mine in my 2014 DX3. Don't remember reading anything about that in my manuals.
Anyone familiar with this issue?

I don't really know but I do recall reading about that a few times over the years.

[Ford Idaho]

Can you hear the air make "popping" noise and does it happen several times?

If does this is one indicator the filter needs to be changed out, how many hours does the engine have for running time?

[Mars]

That's a flat out BS. The brake system sources the air from your tanks not the drier between the compressor and tanks. When the filter starts to clog you usually hear the filter purge valve pop off more often. Most filters will last 2 years or about 60k. Look up the drier manufacture for more info.

[RockHaulerLarry523]

It might help if you drain the air tanks once a month/or more often and before putting it in storage.

Larry

[dlfishing]

Ok, went back and checked the Freightliner M2 manual. There is a section on the Wabco cartridge replacement. It recommends every 2 to 3 years. Don't know if the same applies to RVs and high mileage truck drivers.
It refers to two types of cartridges. Don't know how to determine which my DX3 has.

[Ford Idaho]

The number should be on the outside of the housing much like it is on oil filters.

[wana65stang]

For some good info on trouble shooting and tech tips try googling Bendix AD4 or Bendix AD9 . These are two of the most popular air driers.

[Steveboe]

I had an experience where not changing the filter caused the pop valve to fail. Had to replace the whole unit. Around $300 bucks, exchange for a rebuilt. On a Mack truck bought new.
Air is supplied by the tanks but the dryer supply s the air to the tanks so this could be a factor. I would give the mechanic the go ahead, thinking that your air pressure dropped to a point where the parking brake set by itself as a safety when you loose pressure. Cant get killed if you cant move. You should have heard an alarm also.

[dlfishing]

Originally Posted by Steveboe

I had an experience where not changing the filter caused the pop valve to fail. Had to replace the whole unit. Around $300 bucks, exchange for a rebuilt. On a Mack truck bought new.
Air is supplied by the tanks but the dryer supply s the air to the tanks so this could be a factor. I would give the mechanic the go ahead, thinking that your air pressure dropped to a point where the parking brake set by itself as a safety when you loose pressure. Cant get killed if you cant move. You should have heard an alarm also.

How old was your dryer or how many miles when you had to replace it? I am not having a problem now, just want to be proactive.

[Filterman]

Originally Posted by wana65stang

For some good info on trouble shooting and tech tips try googling Bendix AD4 or Bendix AD9 . These are two of the most popular air driers.

OP says his manual talks about a Wabco so it's probably not going to be. AD4 or AD9. Your correct those are the most common Bendix Air Dryers used in later years.

[Filterman]

Originally Posted by dlfishing

I was told a story yesterday by an RV tech about brakes locking up because the filter hadn't been changed in the air filter and that it should be changed every couple of years in a motorhome.
Seems it's time to change mine in my 2014 DX3. Don't remember reading anything about that in my manuals.
Anyone familiar with this issue?

Used to be in the air brake component sales business. There is no danger of a "lockup" . The air dryer does two things ...1) The obvious . It dries the air! 2) It filters the air. The air coming off the compressor is hot due to the fact that it's been compressed. When it cools down, there is the potential for condensation forming in the tanks and the system that is the death of the electronic components in the later model air brake systems. The dryer removes the moisture in the air by way of the desiccant cartridge in it. It also incorporates a filter in that cartridge that removes contamination. When the compressor cycles and you hear the jet of air, that's the DV (dump valve) ejecting the moisture from the cartridge . The replacement cartridges are available from any heavy du ty truck parts store in your area. A number of companies carry the Meritor Wabco dryer so go to your local Traction Heavy Duty store or any other aftermarket ( or dealer) outlet and they should be able to help you. Frequency of change is entirely dependant on the humidity in the areas you travel, and temperature differential (the cooler the ambient temperature the more opportunity for condensation in your tanks). Once a year is a good guideline but if you are only running half the year your probably fine with every second year. It's cheap insurance to keep the expensive valves in the air system clean and dry. Good luck.

[Steveboe]

I replaced the dryer at about three years and 60,000 miles. Doing the labor myself I noticed the changing the entire unit was no harder than changing the filter only. at least that was the case in my application. The replacement unit outlasted the original one. Still going today.

[dlfishing]

Originally Posted by Filterman

Used to be in the air brake component sales business. There is no danger of a "lockup" . The air dryer does two things ...1) The obvious . It dries the air! 2) It filters the air. The air coming off the compressor is hot due to the fact that it's been compressed. When it cools down, there is the potential for condensation forming in the tanks and the system that is the death of the electronic components in the later model air brake systems. The dryer removes the moisture in the air by way of the desiccant cartridge in it. It also incorporates a filter in that cartridge that removes contamination. When the compressor cycles and you hear the jet of air, that's the DV (dump valve) ejecting the moisture from the cartridge . The replacement cartridges are available from any heavy du ty truck parts store in your area. A number of companies carry the Meritor Wabco dryer so go to your local Traction Heavy Duty store or any other aftermarket ( or dealer) outlet and they should be able to help you. Frequency of change is entirely dependant on the humidity in the areas you travel, and temperature differential (the cooler the ambient temperature the more opportunity for condensation in your tanks). Once a year is a good guideline but if you are only running half the year your probably fine with every second year. It's cheap insurance to keep the expensive valves in the air system clean and dry. Good luck.

Ok, I'm sure you know what you are talking about....couple of questions
1) It's clear that the cartridge has to be replaced at some time...why? Does it get plugged up with moisture, contaminates? If so then I assume it cannot send compressed air to the reservoir tanks, thus no air to operate the breaks.

2) it's my understanding that the air releases the breaks otherwise they stay locked up.....is that correct?

[Steveboe]

You are correct in that your brake system will not release the park brake without about 50 or 60 PSI. The brakes will also lock up if air pressure drops below that level of PSI. When in a tight spot when you are applying the brakes over and over in a short time, you might also hear the alarm sound before the brakes would lock.

[Filterman]

Originally Posted by dlfishing

Ok, I'm sure you know what you are talking about....couple of questions
1) It's clear that the cartridge has to be replaced at some time...why? Does it get plugged up with moisture, contaminates? If so then I assume it cannot send compressed air to the reservoir tanks, thus no air to operate the breaks.

2) it's my understanding that the air releases the breaks otherwise they stay locked up.....is that correct?

The desiccant in the cartridge eventually becomes super saturated and will not remove any more moisture. The problem with thus us that it won't immediately effect your brakes but can play havoc with the components and if you operate in a freezing area, you can actually get a free zip anywhere downstream of the compressor in your system.

As mentioned above " brake lockup" is caused by lowair pressure in the system which technically has nothing to do with the air dryer unless your cartridge became so dirty or "wet" that the system couldn't build air. The "locking "of the brakes is a fail safe system, so that should you lose air in the system, the brake actuators ( which are held off with air pressure and actuated by a heavy spring) will apply the brakes. It's the same system that acts as your parking brake. When you hit the oark brake button on the dash it dumps the air out of the brake chambers (actuators) and applies the rear brakes with spring pressure. Back to the original post......I would recommend making your air dyer cartridge change part or annual or every second year maintenance. Again.......depends on your mileage run and climate. Hope this helps.