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Air Tank Drainage

OK. I admit it. I know I have to open the air tank valves to purge any water condensation. I have actually been told that  this should be done daily?!! Here'e the " thing".....1) do I raise the coach to high to get under the rig? 2) when I open the valve, won't the coach lower?? 3) do you guys do this regularly??? getting under the coach to reach the valves is tricky. I need some guidance here. Thanks, and .....happy trails.......
ALSO....... we experience sewer smell while traveling. I bet there is a solution to this problem. I'm all ears ( and nose ) .
Glenn and Amy Beinfest
2001 36' U320
#5812
2014 Honda CRV

No Whining on the YACHT

Re: Air Tank Drainage

Reply #1 –
The drain valve can be reached from the drivers side of the coach without getting under the coach.  I drain mine every time I think about it.  Usually not every day.  1 drain behind left front tire and 1 ahead of left rear tire on my coach.
Larry & Karen Pontius
2007 Nimbus

Re: Air Tank Drainage

Reply #2 –
OK, lets discuss what the air tank drains are for.

If you ever get moisture, oil or worse white powder from the air tank drain(s), it means YOUR AIR DRYER HAS FAILED.

The air dryer is a component that needs regular maintenance-- say every three or four years.

We have seen a number of posts on what happens when an air dryer fails-- the desiccant (white powder) can get in the whole air system.  Thousands of dollars worth of clogged valves, lines, ride height valves, air brakes........

So, think of the tank drains as a report card ONLY.
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 Drainage

Reply #3 –
Your wet tank drain valve is on driver's side just in front of the rear tire wheel well at the very bottom of the coach.  The wet tank is the only one you need to check daily/weekly.  The secondary tanks (Front tank and rear tank although both are in the front of the coach) should only need to be drained if dryer fails and you have a  lot of water in wet tank.

Regarding sewer smells.  I fought odors for over a year.  I can not smell much of anything, but my DW has a nose like a bloodhound.  I thought we were going to have to sell the coach.  I changed the Air admittance valve in the bathroom cabinet behind the toilet with the fold down door.  I later replace the admittance valve under the kitchen sink.  Finally after finding leaks around the toilet I replaced the wax ring under the Microphor bowl.  This finally fixed the smell problem.  No more smells and a happy DW.  I can keep the coach.

Apparently when the PO worked on toilet they slid the toilet back after setting the wax ring and left a gap allowing smells and water to escape at the bottom of bowl.


ETA:  Never get under your coach without placing blocks on either side of the airbags.  There are other posts covering this.
1998 U320 40'
2005 GMC Yukon
MC# 17609

Re: Air Tank Drainage

Reply #4 –
I have a smell also that just started recently. I think it might be the wax ring.. Watch out when you do the front drain and do not sit under it.. I makes a real mess if it has water in it and will ruin any shirt you have on.. Not sure how I know that one

Re: Air Tank Drainage

Reply #5 –
On the sewer smell you one way vent valves have failed. Usually the at the top of a pvc pipe in bathroom and kitchen cabinet. They screw off the pvc and replacements are available at any Home Depot, lowes, etc.
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Air Tank Drainage

Reply #6 –
any pics of the different valves and where they might be hidden behind the toilet? Air Admittance valve?That could allow the smell?

How to test and so on?

Thanks

Re: Air Tank Drainage

Reply #7 –
Quote from: DavidS –
any pics of the different valves and where they might be hidden behind the toilet?
"Search" tool is your friend.  I searched "air admittance valve" - this thread was the first hit:

Grey Tank Vent (aka air admittance valve)
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air Tank Drainage

Reply #9 –
Quote from: DavidS –
any pics of the different valves and where they might be hidden behind the toilet? Air Admittance valve?That could allow the smell?

How to test and so on?

Thanks
Yes air admittance valves (studor valves) require maintenance if they leak odors  Download maintenance instructions. They are very low suction pressure activated valves so the valve seats may get fouled by intaking dust, dirt or grit. Old age can make the valve seats to be less supple and leak odors. Some valves can be cleaned by pouring water on the outlet side to dislogge any accumulation..
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Air Tank Drainage

Reply #10 –
Look for valves anywhere the plumbing drain pipes are exposed, like under the kitchen and bathroom sinks, and in the washer/dryer cabinet. 
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air Tank Drainage

Reply #11 –
Quote from: GleamB –
ALSO....... we experience sewer smell while traveling. I bet there is a solution to this problem. I'm all ears ( and nose ) .
Besides checking the air admittance valves as recommended above, you might also check the condition of your holding tank vent (or vents) on the coach roof.  It is conceivable that they could be plugged by a bird's nest.  Don't ask how I know this...

I replaced our original "Venturi" vent with a Cyclone swivel style - seems to do the job.  No stinky tanks!

Cyclone Sewer Vent - Camco 40595 - Sewer Accessories - Camping World
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air Tank Drainage

Reply #12 –
Quote from: GleamB –
OK. I admit it. I know I have to open the air tank valves to purge any water condensation. I have actually been told that  this should be done daily?!! Here'e the " thing".....1) do I raise the coach to high to get under the rig? 2) when I open the valve, won't the coach lower?? 3) do you guys do this regularly??? ..........................
Quote from: Larry & Karen  Pontius –
The drain valve can be reached from the drivers side of the coach without getting under the coach.  I drain mine every time I think about it.  Usually not every day.  1 drain behind left front tire and 1 ahead of left rear tire on my coach.
Look at your wet tank "report card" more frequently when in damp, cool, low elevations, less frequently in dry, hot, high elevations.  A few seconds blowdown onto your fingers or a colored cloth will tell you if you have moisture, oil, desiccant, etc. presence in the wet tank.  A few seconds air release is not going to change tank pressure appreciably and the coach air bags will not change.

As far as bleed valve locations, not all FT's are the same. But the standard bleed fitting arrangement for wet tanks is generally in front of street side dual drive wheels.  Front tanks may or may not have bleed valves accessible at the street side of the coach for the Front, Rear Brakes and Aux Storage tanks. 

On our 2002 coach, I must safety block the coach and then climb under to access the bleed valves that are located only on the bottom of each of those three tanks.  But, it is very important to do those tanks as well (perhaps equally important to the wet tank) because those tanks receive air from the aux 12Vdc compressor and when my aux tank desiccant gets weak, moisture there is generally my first indication that I need to change out my aux compressor desiccant, even before I see a color change in the desiccant in the desiccant filter cup (probably because my filter is positioned such that it is very hard to get to and see clearly deep in the street side, number three bay.

HTH,
Neal
The selected media item is not currently available.
Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: Air Tank Drainage

Reply #13 –
David S, not sure if yours is the same as our 2000  295 as we have one of the Back vents as they are known as in the Plumbing trade, under the bottom  of the angled cabinet behind toilet. I have cut that piece of thin ply out and replaced with another that I just put 2 screws in to hold it in place now for easy removal. This one is tied into the shower plumbing  line and was causing our major stink. The one under sink ( lavatory) was fine.
John H
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Air Tank Drainage

Reply #14 –

I used this one for replacement the first replacement

Amazon.com: Oatey 39012 ABS In-Line Vent, Black: Home Improvement

Used one of these for the second

Air Admittance Valve

They both work, the more expensive ,may work better,  the jury is still out.

Use this Amazon link  so ForeForums gets a couple pennies for your purchase
Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs...


ETA: Sorry mods this thread may need to be split

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
1998 U320 40'
2005 GMC Yukon
MC# 17609

Re: Air Tank Drainage

Reply #15 –
Quote from: GleamB –
2) when I open the valve, won't the coach lower??
Newbie comment:  looking at the air system schematic, it seems that if each leveling manifold's (aka 6-pack) supply-side check valve is functioning, there should be no change in coach height -- even if you drain the HWH tank completely.  That's the way it works on my 03 U320 anyway.  Because I used to have massive leaks -- read very loud missing noise leaks, not tiny seeps -- in the HWH air system (air for leveling and slide-out bladders), my HWH tank used to always be at 0 psi after only a little while.  Yet the coach held level configuration for over a week.

On mine there are 4 tank drains.  In front of the left front tire there are three ball valves -- left valve is the HWH tank, middle valve is the front brakes tank and right valve is the rear brakes tank.  As mentioned above the ball valve in front of the left rear tires is the wet tank drain.

Keep in mind I'm a newbie and only know a tiny amount about one model coach -- mine.  There other folks on here know immensely more than I.

Mark
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Air Tank Drainage

Reply #16 –
Quote from: Mark Duckworth –
it seems that if each leveling manifold's (aka 6-pack) supply-side check valve is functioning, there should be no change in coach height -- even if you drain the HWH tank completely.
This is a correct statement.  In fact, this is a good way to verify the condition of air bags and air bag supply hoses.  Air up the coach to travel height, wait for air compressor to "unload" (air drier pops off), then shut down engine. Note pressure in "front" and "rear" tanks (on dash gauge).  Open wet tank drain valve and bleed off all tank pressure.  Close wet tank drain valve.  The coach should remain at travel height for some period of time...several days, at least.

Additional info:  After you drain the wet tank down to zero, go back inside and again note pressure in "front" and "rear" tanks.  It should not have changed.  If pressure is dropping on one or both of the dash gauges, you have leaking valves in the other two tanks.  But which valves...?

Wait until dash pressure readings stabilize (if they ever do).  If the pressure in a tank stops falling at about 60 psi, this means the check valve between that tank and the wet tank is faulty, but the protection valve on that tank is good.  At that point, if you go back and open the drain valve on the (previously empty) wet tank, you will find it again has some pressure in it.  (Upgrade idea: add a pressure gauge to the wet tank!  Search the Forum for info on this mod)

If the pressure in either "front" or "rear" tank falls past 60 psi and keeps going down, this indicates a faulty protection valve.  See the thread linked below for some further discussion of this subject:

Air Tank Valves R&R
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"