Winterizing air tanks and brake system and is there a check valve between wet and dry forward tank?

[ok-rver]

I will get to winterizing in a little bit. Purchased MH about 4 months ago. I knew about systems on a MH that were common on a sailboat and engine stuff but never had air brakes b4. Bought unit on consignment so dealer did not have a lot of time involved in checking out the systems. Drained air tanks in the first weeks after purchase. Maybe a pint of rusty colored water from wet tank and no water from others. Note: If not sure if you might have water in the tank, maybe slip a hose over the quick connect fitting and aim at some place rusty water does not matter. I had red splatter everywhere around the generator. While picking up replacement air tank pressure control valve from Weldon Truck Parts in Tulsa and they recommended running an antifreeze/drying liquid thru the tanks(CRC brand). I connected a 2' length heater hose to a female quick connect using a hose clamp and snapped onto the male air fill in gen compartment. Air tanks at atmospheric. Turns out the alcohol based product flowed into tank without having to put air pressure to the hose. added 1/2 of a quart and drove around a bit to slosh around in tank and then drained tank thru fitting (using hose to direct flow, I can learn). repeated, first few times, out came a lot of rust with the liquid. around 4th time, fluid was clear.  Replace dryer cartridge at this point. It had water in it. 

It was recommended to add the antifreeze at the dryer by pulling a line loose and pouring into the line. We hope to never be in seriously cold weather, headed for South Texas area in January and current storage bay is very well insulated. Thinking the hot air from the compressor will carry any water to the wet tank. I really did not want to disconnect fittings at dryer.

What I have been told is the alcohol evaporates into the air in the wet tank and flows thru the tanks, lines and brake components picking up any moisture as it goes thru and is exhausted by the brakes or by bleeding tanks. Seems reasonable to me. No moisture therefore no freeze up if caught in freezing weather.  I needed to get my tanks to atmospheric pressure the other day and opened the wet tank vent. Out came about a 1/4 of a quart of clear alcohol. maybe 2,500 miles since the last time I added 1/2 quart of alcohol so it is evaporating thru system. after completing the project, re-added 1/2 quart. This time I used a smaller hose and clamped to the round section of the male quick connect. 

I have figured out that the male air connect goes into the wet tank. the female quick connect and tee with valve is connected to the bottom of the dry front tank. when bleeding down, I now use the dry tank vent and let the wet tank flow to the dry. 

I can see a weld line at the center of my forward tank for a bulkhead. Anyone know if this has an open port between the tanks in the bulkhead or is there an external check valve/connecting line somewhere that I am missing?  It seems like I still had a bit of pressure in the dry tank after the wet tank was at atmospheric.

[Jdw12345]

It sounds like it might be a good idea to service the air dryer if you haven’t.
 

 Jmo

[Bob Jones]

3 minutes ago, Jdw12345 said:

It sounds like it might be a good idea to service the air dryer if you haven’t.
 

 Jmo

Ditto. All we have ever done in 21 years (including using the unit in the snow almost every year) has been to periodically drain the tanks and maintain the air dryer. It's job is to keep the air clean and dry. If it's working right and you regularly purge the tanks you're golden.

[Ivan K]

About the check valve, there is a one way valve in center of the divider inside the front tank. It should be serviceable through a side plug but I hope to never find out how easy it is. The plug on mine isn't very large for doing that but is accessible with the wheels off from both sides of the tank.

[jacwjames]

I am not an expert on these systems, learn something new every day.  My Monaco DP has become my hobby so I spend a lot of time reading a couple different forums, probably a couple hours a day.  If I find an interesting article or post I'll even save it to my files.  If I read something that peaks my interest I do some more research.

That being said I have not seen posts as to winterizing brakes.

So this peaked my interest and did a quick search and found this article,  https://www.trucker.com/equipment/trucks/article/21746777/winter-maintenance-tips-for-braking-systems   ,  at the very end it has this.

"Finally some road-call advice if your brakes “freeze” during cold weather: while adding alcohol to unfreeze brake components is a “traditional” solution and may solve an immediate problem, it can damage seals in the air brake system, requiring additional unexpected service down the road. That’s why we don’t recommend using alcohol in air brake systems under any conditions."

I replace my air dyer filter about every 3 years.  I have never found any moisture in my system, I guess I'll continue to do that. 

[ok-rver]

I also did some additional research after the above comments. Sales guys peddle products that make them money, maybe not knowledgable about the subject. I found an article by Bendix that advised not to use antifreeze in their systems. My plan now is to drain the liquid from the tank. In my instance were the previous owner neglected maintenance, I would probably again flush the rust from the tank using small amounts of liquid but not leave the liquid in for any time. As stated in my original post, I installed a new premium dryer canister a couple of months ago as part of this process. I see that some dryers may also have an oil canister. I do not see that on mine. I do not have oil coming out the purge valve port and the system vents at 125 psi. Is there other maintenance that should be performed?

[jacwjames]

11 minutes ago, ok-rver said:

I also did some additional research after the above comments. Sales guys peddle products that make them money, maybe not knowledgable about the subject. I found an article by Bendix that advised not to use antifreeze in their systems. My plan now is to drain the liquid from the tank. In my instance were the previous owner neglected maintenance, I would probably again flush the rust from the tank using small amounts of liquid but not leave the liquid in for any time. As stated in my original post, I installed a new premium dryer canister a couple of months ago as part of this process. I see that some dryers may also have an oil canister. I do not see that on mine. I do not have oil coming out the purge valve port and the system vents at 125 psi. Is there other maintenance that should be performed?

Sounds like a good plan.

FWIW, I just got done fixing leaks on my rig.  I replaces all the Pressure Protection Valves and two check valves.  All of these have rubber type diaphragms or seals, no doubt that any liquid would settle onto these components and if not compatible would cause problems.  (didn't know any of this before I started working on it, but any part I took off I took apart and inspected).

[Jdw12345]

Adding alcohol to the newer air systems is not recommended because of all of the ABS systems to my understanding.

 Years ago it was acceptable, the modern day air dryer if working correctly and maintained should be sufficient.

 I was in the trucking industry for myself for just over 20 years ( long haul from Mn to California)  I always used OE air dryer parts and replacement desiccant cartridges/filters, ya you can save a bit of money buying aftermarket parts, some systems on my equipment I won’t go that route, air systems was one of them, jmo. 

 

 You are going to want to make sure that the heating element is working correctly and the purge valve is working correctly and smoothly, not sure what air dryer you have, I’m assuming it’s a Wabco by the year of your coach, here’s a link to everything you probably need to know about the air dryer you have and the different variations of it.

There’s a lot of info in this reading and it might take a bit of reading to understand what dryer you have so take some time and educate yourself, it sounds like you are interested it maintaining your coach yourself!

 

https://www.wabco-customercentre.com/catalog/docs/mm34_web.pdf

 

[Ivylog]

A properly working air dryer should result in no water in the system and NO need to do anything different for cold weather operations.

I would have drained the water and replaced the air dryer filter BUT I’m not into doing much of anything some say we should do annually.

[Jdw12345]

If your not running your coach every week for 8 hrs a day I wouldn’t worry about servicing the dryer yearly, the majority of folks are lucky if they put on 10 thousand miles a year, when I was trucking I’d put on close to 13 thousand miles a month and I serviced my dryer yearly, if you service the dryer on your coach every three years you should be just fine.

One other thing I always looked after was air leaks, obviously the less air you have to replace the less air the dryer has to process!

   JMO

Edited December 14, 2021 by Jdw12345

[Old Dog]

An often overlooked source of water in the air system is the auxiliary 12v air compress. The factory system has no dryer or seperator installed and in my case with air leveling the compressor runs a couple times a day for 30-60 seconds. After going through pressure switch every 6 months I installed an air seperator with an auto drain and haven't had to replace another switch in 3 years. Also much easy then trying to get get to the aux tank drain. Doesn't affect the brake side of the air system. Hope this helps.

[Ivan K]

Our HWH aux compressor has a factory water separator and auto drain (that helps but hardly 100%) but I am still curious to see how much moisture could potentially  accumulate in those air bags that have no way to drain once water got there, other than in a vapor form. I never had any water from any tank so not worried about it, especially since our aux compressor is wrongly plumbed directly into the wet tank from factory but still see it as possibility over the years. I still have the original airbags and one day I'll find out.

[ok-rver]

The link provided by Jeff does a good job of explaining the different types of Wabco dryers and how the systems work. Turns out I have a 1200 with the regeneration valve. As I stated earlier, I installed a Wabco dryer cartridge about 3 months and 3k miles ago. The purge valve opens and I get a blast at around 125 to 130 psi. Only lasts about a second. If on a gravel parking lot, enough air that small gravel is flighting every direction. Under regeneration valve in the manual, it sounds like maybe this should be 5 sec with a 10 psi drop in tank pressure. Does that happen on other MHs?

The pictures of the heater show what appears to be a snap disc thermostat installed inside the housing. Does not look like this would be "fun" to pull and test. Maybe I will remember to crawl under MH some morning when its 30 deg outside and see if the dryer housing is warm. Not sure if this is powered by the ignition key being on. 

Posts above discussed servicing the air dryer. Are there other actions that need to done?

[Jdw12345]

ok-rver, I just reread your original post, I’m thinking the moisture in your air tanks was due to lack of maintenance to the desiccant and not draining the air tanks on a regular basis. Sounds like your on the right track now.

I’m betting that the dryer has never been completely rebuilt unless you know better, I always assume the worst and proceed accordingly, for what it costs to do it at your will vs somewhere undesirable, it just makes sense, to me, to do it all at the same time!  Then your not driving down the road at below freezing temps wondering if problem's will a rise!

 As far as the length of time the dryer purges,  it’s just a quick “shhhh”, it’s just enough to purge the desiccant, it shouldn’t linger and it should be crisp and clean sounding, if that makes sense! It’s not that costly to rebuild the purge valve, all you need is a inner snap ring pliers and a pick of sorts to get all of the parts out of up there, If you proceed with the purge valve rebuild make sure you get all of the old parts out and replace with the new ones! 
 

 Unfortunately my brain just works that way, service it all and service it completely!

[woodylmiller]

Excellent topic.  Hadn't thought about the aux compressor.  Another "thing" now  on the list of things to do.   Nice.

Woody Miller

[96 EVO]

On 12/19/2021 at 1:52 PM, ok-rver said:

  Under regeneration valve in the manual, it sounds like maybe this should be 5 sec with a 10 psi drop in tank pressure. Does that happen on other MHs?

 

Yes!

If you hold your hand under the purge valve, immediately after the blast from the compressor unload, you should feel a light stream of air for several seconds while tank air dries out the desiccant in the filter. This is the regeneration cycle.

Edited January 15, 2022 by 96 EVO