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RVing message boards => Winnebago-specific issues => Topic started by: Iron Horse on September 15, 2017, 06:58:19 AM

Title: Air Brake Desiccant air dryer/filter
Post by: Iron Horse on September 15, 2017, 06:58:19 AM
We have a 2007 Winnebago Journey 36G and I'm doing my yearly service. My question is about the desiccant air filter on the brake system. How often are these canisters changed. It is still exhausting normally but has been in there about three years. We only put two to three thousand miles on the MH yearly. It has 34,500 miles on it now and I have changed it twice over the years. Thanks
Title: Re: Air Brake Desiccant air dryer/filter
Post by: RedT on September 15, 2017, 07:47:10 AM
When my coach was 2 years old, I talked with a factory (Haldex) rep concerning replacing the desiccant. He told me a lot depends upon the operating environment. Since my travels were in the southwest with low humidity, he advised looking at the discharge spot left on the ground when air pressure is relieved. A dry spot indicates no problem. A wet spot means it's due change.
Title: Re: Air Brake Desiccant air dryer/filter
Post by: afchap on September 15, 2017, 07:48:57 AM
My 2002 Spartan chassis maint schedule says "24 mo check/replace air dryer desiccant cartridge." Additional note says  "can go 4-5 yr but avg about 3".
Title: Re: Air Brake Desiccant air dryer/filter
Post by: BRex on September 16, 2017, 12:45:12 AM

Our '97 Country Coach had its original Bendix AD-9 air dryer for the first 14 years. All three tank drains were dry, never any indications of moisture anywhere. When I removed it from the coach last year the can was dry and appeared new except for a tiny drop of water near the purge valve.
14 years old but only 17,000 miles. I would not worry about changing the desiccant cartridge until I saw moisture, any, at the air tank drain valves.
Check those monthly.

Good luck,
Title: Re: Air Brake Desiccant air dryer/filter
Post by: Iron Horse on September 16, 2017, 06:41:48 AM
Thanks guys......I think I'll go ahead and change it since I already have one on hand. Been a little lax on draining the tanks, I have to remember this as one of my must things to do.
Title: Re: Air Brake Desiccant air dryer/filter
Post by: Gary RV_Wizard on September 16, 2017, 07:52:28 AM
The air dryer is an item included in Freightliners recommended service intervals for RV chassis.  For your 2007 model Freightliner chassis, it will be every 36 months. With your very low mileage it is probably even longer than that, but keeping the dryer at optimal performance makes routine draining of the air tank moisture pretty much unnecessary.

You can probably extend the interval between cartridge changes to save a few bucks, or you can enjoy the peace of mind of knowing your air system is dry enough so that the brakes are unaffected.  Make your own call...
Title: Re: Air Brake Desiccant air dryer/filter
Post by: Mile High on September 17, 2017, 10:42:16 AM
Is that something I should drain when I winterize?  I don't think I even know where it is.
Title: Re: Air Brake Desiccant air dryer/filter
Post by: Gary RV_Wizard on September 17, 2017, 11:45:05 AM
It's not a "winterize" thing. You are supposed to drain the accumulated moisture from the air tanks periodically, but that period should be really long if the air dryer is working as designed. You can't drain the dryer cartridge - it has to be replaced.

Any air compressor squeezes water from the air as it works and the air tank accumulates the excess water. Two problems associated with that: rust in the tank and water getting into the air brake system and interfering with braking.
Title: Re: Air Brake Desiccant air dryer/filter
Post by: John Canfield on September 17, 2017, 05:39:15 PM
You are supposed to drain the ping tanks daily when operating.
Title: Re: Air Brake Desiccant air dryer/filter
Post by: Mile High on September 19, 2017, 10:04:02 PM
guess I better read up on the air system.  I'm not sure where the ping tanks are.