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Topic: Air Tank Water Drain Valves Nomenclature Question (Read 696 times) previous topic - next topic

Air Tank Water Drain Valves Nomenclature Question

There are three air tank drain valves on our coach that are located on the driver's side just forward of the front tire.

When opened, the two inboard ones expelled hardly any water, but the outboard one seemed to release a fair amount.

Can someone please tell me what each valve goes to?

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #1 –
Of the 3 up front; two are front and rear brake tanks, one is wet tank and one forward of rear wheel is auxiliary tank, if I remember correctly. I don't remember which is which but open one and see which brake air gauge looses air (engine off).  Same for locating auxiliary valve, auxiliary pump will come on.  Hope this helps.
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #2 –
Maybe they changed them from 2001 but in mine the wet tank is near the rear axle with the bleed valve near the driver's side rear wheel opening.  In front just behind the generator is the aux tank for the air bladders and HWH stuff.  The other two up front are front and rear brake tanks.  Bleed valves for those should be near the driver's side front wheel well.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #3 –
More critically than "which drain is for which tank, if you have ANYTHING  but clean, dry air from any tank drain, IT MEANS YOUR DRYER HAS FAILED.

So, water, oil and worst of all white powder (meaning the dryer dessicant has broken free and now can clog all your air valves (brake and suspension).

Bottom line, service or replace the air dryer.

My recommendation is to buy a factory REMAN (yes the factory that manufactured the unit, not a Chinese "almost fits").  That gives you not only new filters, but also all valves, check valves, heater, etc. About all that is reused is the metal case.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #4 –
Quote from: wolfe10 –
More critically than "which drain is for which tank, if you have ANYTHING  but clean, dry air from any tank drain, IT MEANS YOUR DRYER HAS FAILED.

So, water, oil and worst of all white powder (meaning the dryer dessicant has broken free and now can clog all your air valves (brake and suspension).

I thought the tank drains were for draining water and oil. 

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #5 –
Think mainly the drain is for moisture,and for bleeding air for any reason,Brett is right if you have water and/or oil get the reman
air drier,ASAP.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #6 –
Think of the air tank drains as the "report card" for the condition of the air dryer.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #7 –
The outboard drain did not have that much water draining (maybe 1 cup), and very little PSI.  All the other drains (including the wet tank) were/are dry with probably 125 PSI.

From looking at the air schematic I think that the one with little PSI is for the slide out seal air tank, and the other two
are front and rear brakes.  So I checked the auxiliary compressor and found that the desiccant beads needed to be changed as they were pink.  Although I changed them maybe a month ago, it's been real hot and humid here.

So, with the wet tank dry, which is first in line after the dryer, I'm hoping that things are OK and I don't need a new dryer right now.



Re: Air Tank Water Drain Valves Nomenclature Question

Reply #8 –
So ---  an air dryer by definition would be removing the "water" out of the air. My question is, where would the "oil" be coming from and ( two part question) is a tablespoon of oil too much. I haven't checked our u280 front tanks for about 5000 miles. Way under the nose and kind of forgot about em.  Compressor oil would be my guess. 
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #9 –
Quote from: Bob & Sue –
So ---  an air dryer by definition would be removing the "water" out of the air. My question is, where would the "oil" be coming from and ( two part question) is a tablespoon of oil too much. I haven't checked our u280 front tanks for about 5000 miles. Way under the nose and kind of forgot about em.  Compressor oil would be my guess. 

Correct.  it would be oil getting by the rings of the engine driven compressor and then by the dryer filter.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air Tank Water Drain Valves Nomenclature Question

Reply #10 –
It would appear by following the threads (rabbit trails) on the beamalarm site that a trace of oil at the reservoir as measured by a "bendix cup" is normal and can be "returned to service".  I will be checking more regular.
  Apparently the air dryer is designed to remove water and oil from the air and from the system.  But if some oil is passing thru I may be comming up on a air dryer service.
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR