Draining Air Tanks

Topic: Draining Air Tanks (Read 1941 times) previous topic - next topic

Draining Air Tanks

July 27, 2010, 12:35:15 pm

After searching archives, asking at FT, reading FT Coach Manual - I still don't have the answer to a few questions about draining the air tanks -

Please chime in

I know where my air tanks are, that's easy - I understand about mainly draining the rear one and air dryer etc etc

Manual says: Air Tanks (in plural) meaning all three of them:
"Drain tanks: daily in cold weather. Weekly in warm weather"

My questions are:

At what point to drain them re: At end or beginning of trip? What about between trips? (We full time so there is no storage/winterizing prep to consider here)

When going under front end of coach to open valves - What happens - does the coach lower? Can I raise the front of coach to make access easier? If I raise the front up will it lower while I am under there?

I've this huge FEAR of going under the coach

- WHY can't there be an extension on the front tanks for a valve switch easily accessible as the rear tank valve is?

Re: Draining Air Tanks

Reply #1 – July 27, 2010, 12:51:40 pm

I was told to drain the air tanks once a month, but I am in a dry climate.

My valves are all located along the bulkheads just in front of the right tires, and are easy to reach from the side of the rig.

Re: Draining Air Tanks

Reply #2 – July 27, 2010, 01:34:20 pm

And the practice I have followed for years is to drain monthly. And when I do, I just let a short blast of air out, and always have a wad of paper towels in my hand in the air stream - I have never, ever seen any water, but if it's there, I want to be able to tell it from the paper towels being damp. (18 years, 300K miles and 6 Foretravels)

I get the Air Dryer serviced annually.

I have been told it is a simple "plumbing" job to get the valves re-located to a more convenient spot, but haven't ever done that. Our first Unihome, a 1988, had spring-loade valves actuated by a Lanyard which extended from the valve to the outside edge of the Coach - just a quick pull and I was done! Haven't seen that installation since.

Re: Draining Air Tanks

Reply #3 – July 27, 2010, 03:00:41 pm

I would suggest that to be perfectly safe, perform some tests before going under the coach so you can see it with your own eyes. 1st, raise the coach at both ends front & back. Make sure the leveling system light is "off". 2nd, go outside the coach and using the drain valve you can get at w/o going under the coach, let the air out. 3rd, notice the level to determine if it drops or not. Do the same steps above with the leveling system light "on". All the above steps should be done with the engine "off". (You may need to run the engine only to raise the tank presssure so you can raise the coach at first).

Re: Draining Air Tanks

Reply #4 – July 27, 2010, 04:12:59 pm

Think of the "air tank draining" as a performance test for your air dryer--THAT IS ALL IT IS.

If you ever get any water or oil when draining the air tanks, it means your air dryer has FAILED and needs immediate servicing/replacement.

Air dryers should be serviced every three years-- sooner if they fail this "Performance Test".

Brett Wolfe

Re: Draining Air Tanks

Reply #5 – July 27, 2010, 05:13:17 pm

I was preparing to do mine at the 3 year point when the unloader valve failed. When I took it apart, we discovered it had likely NEVER been touched since new

Quote

wolfe10 wrote:

Think of the "air tank draining" as a performance test for your air dryer--THAT IS ALL IT IS. If you ever get any water or oil when draining the air tanks, it means your air dryer has FAILED and needs immediate servicing/replacement. Air dryers should be serviced every three years-- sooner if they fail this "Performance Test". Brett Wolfe Brett Wolfe 1993 U240 Moderator, FMCA Forum Moderator Caterpillar RV Engine Owners Club Wolfe10 on RV.net/forum >

Regards,

Re: Draining Air Tanks

Reply #6 – July 27, 2010, 06:05:52 pm

Dave,

WOW. I would say that falls into the category of "luck" or "what they got away with"!

But, you are right-- I have seen that on dryers, hydraulic system filters, etc. Usually caused by lack of knowledge that those items need servicing.

Brett Wolfe

Re: Draining Air Tanks

Reply #7 – July 27, 2010, 06:57:31 pm

What is the difference between dumping the air and draining the air tank?

Re: Draining Air Tanks

Reply #8 – July 27, 2010, 07:14:31 pm

Quote

What is the difference between dumping the air and draining the air tank?

Best Guess:
If you mean "draining the air Tank" with the drain valve on the tank or remoted to wheel well,
that should be the lowest point for water to accumulate and will expel the water in the system.
Dumping the air with the HWH control panel, the air is expelled thru the manifold and not the lowest point.

Front Air Tanks: draining

Reply #9 – September 19, 2010, 02:50:50 pm

Hello All,

Wanted to update results from my asking weeks ago about draining the front air tanks.

Resolved the issue I was having about going under the coach to preform this draining by having Foretravel shop install valve drain extensions to just in front of the driver side front tire on the panel of the generator. Very easy to reach in and turn valves without having to get under the coach. Cost was $300 for the way they did it for my coach. Am very happy.

Thanks to those who took the time to personally email as well as post back when I was struggling with this. Thou all had solid points of dealing with the draining of the front tanks, I still could not mentally convenience myself to go under the coach. Now, I never have to consider that thought again.

Re: Draining Air Tanks

Reply #10 – September 19, 2010, 06:36:42 pm

Brett,
Since the draining the air tank is just a function of verifying that the air dryer is working. Could you just drain the wet tank and if it is always dry could I assume all is good with the dryer? I usually just open the petcock on the wet tank unless I'm under the coach for another reason, but I could re-plumb if necessary for the other tanks.

Thanks for you help,

Brad

2000 U320 4000

Re: Draining Air Tanks

Reply #11 – September 19, 2010, 07:50:22 pm

Brad,

You are right. If the wet tank drain valve always shows dry air, there is no need to drain the front tanks. It's much better to service the air dryer on schedule and never risk the air system.

The other Brett

Re: Draining Air Tanks

Reply #12 – September 19, 2010, 08:10:13 pm

What is involved in servicing the dryer? Does it require any special tools or gauges? Is it something a fairly good MOKanic can do?

Re: Draining Air Tanks

Reply #13 – September 19, 2010, 08:26:06 pm

The other Brett,
Thanks for the reply and that was my opinion too.

Kent,
I had FOT do the service as part of my purchase, but the only issue I could see is the pop off valve. If your dryer has not been serviced regularly that could be an issue. The service itself was easy and the mechanic that did the service completed in about 15 minutes. He did state if the pop valve off breaks off it is a PIA

to remove....mine did not break.

Thanks,

Brad

2000 U320 4000

Re: Draining Air Tanks

Reply #14 – September 19, 2010, 08:38:11 pm

Quote

What is involved in servicing the dryer? Does it require any special tools or gauges? Is it something a fairly good MOKanic can do?

haldex_pure_air_plus_air_dryer_rebuild.htm

Re: Draining Air Tanks

Reply #15 – September 19, 2010, 09:31:04 pm

I've read this thread a couple of times and I need some clarification on where these tanks and valves are located. See the attached photos. One shows the three air valves in the driver's side front wheel well. I was told to "bleed" these valves when I fill up on fuel. I usually forget, so its done about once a month or so. Are these the valves you guys are talking about?

I also took a photo of what appears to be an air tank between the front wheels. Is this the "wet" tank" and if so where is the drain valve.

Thanks in advance,

Re: Draining Air Tanks

Reply #16 – September 19, 2010, 09:36:48 pm

Quote

One shows the three air valves in the driver's side front wheel well. I was told to "bleed" these valves when I fill up on fuel. I usually forget, so its done about once a month or so. Are these the valves you guys are talking about?

These are air bleed valves. Front, Rear & slide air tanks.
There should be one by the rear wheels also. That should be the wet tank.

Re: Draining Air Tanks

Reply #17 – September 20, 2010, 01:19:25 am

The valve for the rear tank is located in the front of the wheel well next to the sub floor on the rear driver's side.

Re: Draining Air Tanks

Reply #18 – September 20, 2010, 02:39:38 am

The"other George" here.

So, do I only bleed the wet tank periodically or do I do all the other valves as well? Currently, I try to remember to bleed the wet tank once a month. It never emits any moisture with the air.

Re: Draining Air Tanks

Reply #19 – September 20, 2010, 09:39:27 am

Quote

So, do I only bleed the wet tank periodically or do I do all the other valves as well?

If the wet tank drain valve always shows dry air, there is no need to drain the front tanks.

Re: Draining Air Tanks

Reply #20 – September 20, 2010, 10:26:08 am

Quote

I also took a photo of what appears to be an air tank between the front wheels. Is this the "wet" tank" and if so where is the drain valve.

What is meant by calling it the "wet" tank? My suspicion is that contains air before being treated by the air dryer. I understand multiple tanks for backup and separate brake systems but don't understand why there are 4 air tanks.

Re: Draining Air Tanks

Reply #21 – September 20, 2010, 10:42:57 am

After reading all these posts about draining air tanks, my coach was one of the ones that probably never had the air dryer serviced (55k miles 13 yrs). After servicing 2 yrs ago, I haven't noticed but just a trace of water from any tank. I removed the front tank valves and moved them to a location just in front of the right front wheel, that I can reach without going under. Chose the right side as the left side has the generator exhaust pipe in that location. Made a bracket of angle bolted to the box area under the steps. Used the same type of plastic brake line tube that connects to step, step cover, and air horns to connect the valves to the tanks. About $20 worth of parts from Home Depot, I already had the brake line, left over from the toad brake installation. The Texas CDL test guide says drain the tanks at the end of the day, but that would probably be most applicable to a vehicle without an air dryer.

Re: Draining Air Tanks

Reply #22 – September 20, 2010, 11:13:42 am

Quote

What is meant by calling it the "wet" tank? My suspicion is that contains air before being treated by the air dryer.
I understand multiple tanks for backup and separate brake systems but don't understand why there are 4 air tanks.

Take a look at:
air-brakes-how-they-work

Re: Draining Air Tanks

Reply #23 – September 20, 2010, 02:00:09 pm

A good rule to follow is when you find water in the wet tank, check the condition of the airdryer,The dryer should be spitting the moisture every time the govnor cycles.

Also the wet tank is the first tank after the dryer, then on down stream to the two front tanks.
So if you have water in wet tank, the dryer ain't working correct.

Second, Automatic Slack adjusters are great, but you should check the actual slack once in a while, not all automatic slack adjusters work great.
FWIW
Dave

Re: Draining Air Tanks

Reply #24 – September 20, 2010, 02:52:51 pm

Barry, your description says "Typically there are 3 air tanks or reservoirs" I have 3 drain valves in front amd 1 in back --> 4 tanks. Can you explain?

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