Air dryer maint and canister replacement practices

[R.Wold]

My new-to-me 2016 Ventana has 18,000 miles on it. Freightliner and Bendix suggest a three year replacement interval, so it’s ready by that standard. But Bendix is also assuming over 100k miles. Freightliner doesn’t specify milage but Vehicle Maintenance Schedule Table 00–02 in the RV chassis manual indicates that 45,000 miles corresponds in general to 36 months.

Just to muddy the waters a bit Freightliner offers this:

“ NOTE: Desiccant change intervals may vary from vehicle to vehicle. Typical desiccant cartridge life is three years. However, if experience has shown that extended or shortened life has resulted on a particular installation, then the interval can be increased or decreased accordingly.”

So I have 3 years, 45,000 miles, 100,000 miles, and “it depends”.

I’ll probably just do it when it comes back from the shop where it’s getting some dealership provided (La Mesa) slide work.

But I’m curious - What do you guys do?

[Martind4]

I guess I'm cautious and do it at the 3 year or less timeframe. It's not that expensive and I want to make sure the air system stays dry for brakes and leveling valves.

[jacwjames]

I do it about every 3 years, the cost is negligible. Considering how important the air system is I would caution on the side of changing early vs late.

[Old Scout]

...in theory, the dryer is working if no water or oil is detected during your periodic draining of the reserve[s] air tanks--I am sure we all drain our tanks on a frequent basis--not!...the fear is that the internal desiccant bag may rupture and disperse particles thru the system....according to Bendix service reps input, the final consideration for me is that these systems are designed for commercial trucks that travel 100k miles, sometimes we RVers over think this stuff--your time, your money, your call--IMHO...

[R.Wold]

I only had it for a couple days before it went back in for slide repairs. It got a lot of attention in the service dept before I picked it up, but I didn’t get a checklist of what was done - just a verbal report on the main items. When I get it back I’ll drain the tanks (was a weekly task on fire apparatus) and see what I get out of them.

I’ll start fresh with a new canister when I go through everything else - the thought of an older, although low milage, one deteriorating and contaminating the system is good enough for me. Thanks for that - I didn’t find any mention of rupture in the stuff I read, and this was a city garage thing throughout my career so I never heard about it.

[Old Scout]

...I agree, desiccant bag failure is probably very remote--but critical if it were to happen--classic risk management issue....again, Bendix rep was "reluctant" to sell me a new cartridge unless I had symptoms, eg, water or oil in reserve tank drain...…
PS--small amount of moisture or oil on dryer release valve means dryer is working; lots of oil means a compressor issue. Oil or water in reserve tank drain means dryer desiccant is saturated, as that's the purpose of checking tank drain.

[R.Wold]

I just found this related thread and found it interesting.

https://www.irv2.com/forums/f103/cha...er-386671.html

Because I don’t have a tag mine is much more accessible, although I only had a chance to briefly inspect it before running it down to La Mesa in West Sac to have the slide repairs done.

Fortunately I enjoy equipment maintenance. I’ll check the tanks before I do anything on this but I’ll buy the filter when I buy oil and fuel filters and have it on hand for a maintenance day. The chassis needs a good cleaning too and doing this first will make the service part a lot more convenient.

The original owner bought this thing, drove it for four years and 18,000 miles, had routine maintenance done, and then traded it in on a new big Entegra. I doubt he ever did any creeper time. That’s one of the reasons I insist on low milage rigs - the original owners don’t have time to neglect it enough to do any serious damage.

I’m looking forward to getting the thing home and starting the next chapter in my RV experience. I’ve had truck campers, TT, small 5th wheel, toy hauler, B+, C, A gasser and now this. I think his one will keep me for a while.

[Gary RVRoamer]

I always used the time interval for the air dryer. I never bother with draining the air tanks, so don't have evidence whether the dryer is still working or not. Easier to go ahead and change and not worry about it.

[AE Wanderer]

One thing, before taking the old filter off, make sure the area around it and above it are clean. Do not let any dirt fall into the system with filter off.

[Hooligan]

Freightliner chassis are equipped, as standard equipment, with a
heated automatic moisture ejector on the wet tank in addition to one
built into the air dryer. It is still a good idea to periodically pull the lanyards to see if you have any moisture. If the filter medium does break down over a long period it moves throughout the air brake system.
Cases I heard of that are usually longer periods of neglect.

[canman001]

I replace every two years. I sequence drain the accumulator tanks every chance. Pit access or service. Wet tank, primary, secondary and auxiliary. Sequencing checks the function of check valves.

[Dutch Star Don]

"R. Wold"......that's my link on changing the air dryer filter. I can fix just about anything, but changing that filter was one of the toughest jobs I've ever done. On my 2014, the entire air dryer HAD to be removed because Freightliner mounted it in a position that did not allow you to unbolt the cover. It wasn't technically difficult to do just physically difficult to do without a pit or rack. When laying on your back, you're arms just aren't long enough to reach everything. Freightliner wanted over $400 labor to do the job.

With that said, my 2019 Freightliner is in the same area, but is a spin off filter and will be easier. So, check which one you have before buying a filter, if yours is like my 2014, which I'm guessing it will be (cover is a bolt on) you may want to pass on doing it yourself.

[R.Wold]

Originally Posted by Dutch Star Don

"R. Wold"......that's my link on changing the air dryer filter. I can fix just about anything, but changing that filter was one of the toughest jobs I've ever done. On my 2014, the entire air dryer HAD to be removed because Freightliner mounted it in a position that did not allow you to unbolt the cover. It wasn't technically difficult to do just physically difficult to do without a pit or rack. When laying on your back, you're arms just aren't long enough to reach everything. Freightliner wanted over $400 labor to do the job.

With that said, my 2019 Freightliner is in the same area, but is a spin off filter and will be easier. So, check which one you have before buying a filter, if yours is like my 2014, which I'm guessing it will be (cover is a bolt on) you may want to pass on doing it yourself.

Yes I recognized that and found it interesting. It came up during my general knowledge search. I don’t recall which mine is - I just gave it a quick look and it was dirty, but at least it’s behind the axle and accessible.

Also I didn’t notice lanyards on my valves but I wasn’t really looking - is this a Freightliner standard or a coach builder add-on? On fire apparatus we spec’d color coded valves mounted in an easily accessed driver’s side location for weekly checks.

I’ll bleed the tanks before I do anything, and I don’t expect to find much because as stated earlier by Hooligan, it has a typical automatic bleed valve arrangement, but if the dryer is failing, water and some oil would likely make it to the tanks.

If it’s a spin on type I’ll put one in stock. I don’t exactly live in town...

[Sonic]

Hmmmm, I asked a local RV repair facility to check mine out as part of routine maintenance service last year at the 5 year mark and they said it was fine. If the dryer is that difficult to service, and they didn't charge me to inspect it, how did they know?
I don't see any water when I pull the lanyards and the brakes are working fine, but I'm taking it to a diesel shop that does a lot of big rig work in a few weeks for service, and I'll get their opinion.