Wet tank, no purge valve

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Wet tank, no purge valve

May 08, 2021, 03:12:06 pm

My wet tank has no purge valve, the front two tanks have valves, should I retrofit a purge valve on the wet tank? I was trying to test for moisture in the air system.

Re: Wet tank, no purge valve

Reply #1 – May 08, 2021, 03:32:11 pm

Check the driver side rear wheel well, in front of outside tire, down low and tucked inside the wheel well lip. Little brass 1/4 turn valve.

Re: Wet tank, no purge valve

Reply #2 – May 08, 2021, 03:35:01 pm

Right. The valve is not actually on the tank.

Re: Wet tank, no purge valve

Reply #3 – May 08, 2021, 03:59:34 pm

Thank you thank you!

Re: Wet tank, no purge valve

Reply #4 – May 09, 2021, 10:56:57 am

Newbie question:

Should I occasionally be opening these valves to drain moisture, or is it something to be done only when one suspects an issue?

Same question for the fuel filters. My fuel filter doesn't have a clear window. The manual implies it should be checked every trip, which seems excessive, but maybe that's best practice.

Thanks

Re: Wet tank, no purge valve

Reply #5 – May 09, 2021, 11:06:52 am

Quote from: Joe Phebus – May 09, 2021, 10:56:57 am

Newbie question:

Should I occasionally be opening these valves to drain moisture, or is it something to be done only when one suspects an issue?

YES, OPEN THE WET TANK DRAIN (IN FRONT OF LEFT REAR WHEEL) OCCASIONALLY. CONSIDER IT THE "REPORT CARD" ON THE CONDITION OF THE AIR DRYER. ANYTHING BUT CLEAN, DRY AIR MEANS THE DRYER HAS FAILED.

Quote from: Joe Phebus – May 09, 2021, 10:56:57 am

Same question for the fuel filters. My fuel filter doesn't have a clear window. The manual implies it should be checked every trip, which seems excessive, but maybe that's best practice.

IF YOU HAVE A CLEAR BOWL, YOU WOULD BE ABLE TO SEE EITHER WATER OR SOLID CONTAMINANTS, SO NO NEED TO OPEN. IF YOU CAN'T VISUALLY CHECK, THEN, YES A GOOD IDEA TO CHECK THE FIRST TIME YOU STOP AFTER FILLING UP TO MAKE SURE YOU DID NOT GET CONTAMINATED FUEL.

Thanks

Re: Wet tank, no purge valve

Reply #6 – May 09, 2021, 04:35:57 pm

I have a clear bowl on mine but I don't go by that. I change the fuel filters every oil change and always carry a spare. 1 primary and 1 secondary if you have both.

Re: Wet tank, no purge valve

Reply #7 – May 09, 2021, 04:38:46 pm

Quote from: Twig – May 09, 2021, 04:35:57 pm

I have a clear bowl on mine but I don't go by that. I change the fuel filters every oil change and always carry a spare. 1 primary and 1 secondary if you have both.

Totally agree on changing filters.

But, he is asking about "checking every trip" A different beast.

Re: Wet tank, no purge valve

Reply #8 – May 09, 2021, 04:48:12 pm

Quote from: Chuck & Jeannie – May 08, 2021, 03:32:11 pm

Check the driver side rear wheel well, in front of outside tire, down low and tucked inside the wheel well lip. Little brass 1/4 turn valve.

FYI this is also where a tow truck would hook up their air to pressurize your suspension in the event you ever need to be towed.

Don't let them try to hook it up to your bladder tank at the very front, because they'll want to :-)

Re: Wet tank, no purge valve

Reply #9 – May 09, 2021, 05:31:43 pm

Quote from: Elliott – May 09, 2021, 04:48:12 pm

FYI this is also where a tow truck would hook up their air to pressurize your suspension in the event you ever need to be towed.

Elliot,

That might be true for your 2001 model coach, but is not correct for the OP's '93 U280. His coach should have a "tire filler" connection in the small storage bay just aft of the entry door. On the '93 model, that air connection leads directly to the wet tank with no check valves, and is the one the tow truck should tie into.

You ARE correct in saying that the tow truck should tie in where he can keep the wet tank aired up. By doing so, it insures that the suspension will remain pressurized (in travel mode) while the coach is being towed. If the driver connects to one of the brake tanks at the front of the coach, only 1/2 of the suspension will be pressurized. Not good.

Re: Wet tank, no purge valve

Reply #10 – May 09, 2021, 05:40:12 pm

Quote from: Joe Phebus – May 09, 2021, 10:56:57 am

My fuel filter doesn't have a clear window.

You'll find that some fuel filters have a drain valve in the bottom in lieu of a clear window. If you have one of those, you can open the valve and collect a small sample of fuel in a clear cup. Let it settle out for a bit, then see if there is any water in the bottom.

Re: Wet tank, no purge valve

Reply #11 – May 09, 2021, 05:42:16 pm

Quote from: Chuck & Jeannie – May 09, 2021, 05:40:12 pm

You'll find that some fuel filters have a drain valve in the bottom in lieu of a clear window. If you have one of those, you can open the valve and collect a small sample of fuel in a clear cup. Let it settle out for a bit, then see if there is any water in the bottom.

And, ALWAYS with the engine OFF, repeat OFF!

Re: Wet tank, no purge valve

Reply #12 – May 09, 2021, 05:52:52 pm

Quote from: Chuck & Jeannie – May 09, 2021, 05:40:12 pm

You'll find that some fuel filters have a drain valve in the bottom in lieu of a clear window. If you have one of those, you can open the valve and collect a small sample of fuel in a clear cup. Let it settle out for a bit, then see if there is any water in the bottom.

Thanks, Chuck. Do I need to prime the filter after doing this or is that not necessary?

Re: Wet tank, no purge valve

Reply #13 – May 09, 2021, 05:55:52 pm

Quote from: Joe Phebus – May 09, 2021, 05:52:52 pm

Thanks, Chuck. Do I need to prime the filter after doing this or is that not necessary?

Not necessary. The filter will refill itself- no problem.

Re: Wet tank, no purge valve

Reply #14 – May 10, 2021, 01:54:05 am

You all are awesome! A little learned here every day.

Re: Wet tank, no purge valve

Reply #15 – May 10, 2021, 11:45:50 am

Quote from: Chuck & Jeannie – May 09, 2021, 05:31:43 pm

That might be true for your 2001 model coach, but is not correct for the OP's '93 U280.

Glad you pointed that out, thanks Chuck. No slide bladder tank on his coach either

To expand on my comment regarding the bladder tank: it sounds like most tow drivers haven't seen a system like ours (mine) so it's a natural assumption for them to think it's the wet tank given it's the "odd man out" in terms of how it looks and has a drain on it (unlike the other two). It's further compounded by the wet tank actually being in the back, between the wheels where it's difficult to spot. It took me a good few minutes to convince my tow driver this was the case.

Another fool's tip errrrr I mean PRO tip: the driver's side awning hooks are perfectly placed for the tow truck's airline to be hung on all the way to the back where the valve is. Good to have a few heavy duty zip ties with you for this alone.

Re: Wet tank, no purge valve

Reply #16 – May 10, 2021, 12:11:43 pm

Makes me kinda wonder why the engineers who designed these coaches (not just Foretravel but all coaches with complicated air suspensions) didn't think about the possibility that the coach would need to be towed at some point. It would have been pretty simple, when laying out the air system, to include a quick connect at the front end of the coach. Then, when the tow truck driver plugged into that quick connect, air pressure would be piped to the correct air tank for that particular coach. No guessing! No stringing the air line down the side of the coach where it can cause other collateral damage to paint and body work.

But I guess that would have required foresight.

Re: Wet tank, no purge valve

Reply #17 – May 10, 2021, 12:13:34 pm

If I ever need a tow , hopefully not, knock on wood, where should the air line be connected on my 2003 U295? I always thought it was the air coupling in the passenger side bay with the propane tank and fuel tank.

Second question: is that air coupling wet or dried air?

Thanks.

Re: Wet tank, no purge valve

Reply #18 – May 10, 2021, 12:22:54 pm

The coupling at the propane tank is after the air drier so using that chuck moisture can be put into the system. I put a male quick
coupler fitting just before the air drier. The disadvantage of that is for towing and air line has to be run to the rear of the coach.
On my Monaco they had a air chuck at the front of the coach but I don't think it went to the air drier.

Re: Wet tank, no purge valve

Reply #19 – May 10, 2021, 12:23:29 pm

Quote from: Tom Lang – May 10, 2021, 12:13:34 pm

If I ever need a tow , hopefully not, knock on wood, where should the air line be connected on my 2003 U295? I always thought it was the air coupling in the passenger side bay with the propane tank and fuel tank.

Second question: is that air coupling wet or dried air?

Tom,

You need to look at your air system schematic. First, you need to know which air tank on your coach supplies air pressure to everything that would require air pressure during a tow. Second, you need to find the best/easiest place to supply an outside source of air to that tank. There can't be any check valves (that would prevent adding air) between the connection point and the tank of interest.

If the air coupling on your coach comes off the wet tank, or any tank downstream of the air dryer, it is dried air.

When a tow truck supplies air pressure to the coach under tow, that should also be dried air that went through the air dryer on the tow truck.

It is possible the air coupling in your propane bay will not allow outside air to flow "backward" due to a check valve somewhere in the line. You can tell if this is the case by looking at your air system diagram.

Re: Wet tank, no purge valve

Reply #20 – May 10, 2021, 12:31:55 pm

Thanks Chuck I never thought of the tow trucks air already been dried. I put the fitting at the rear of my coach to work on the
coach without having to start the engine.

Re: Wet tank, no purge valve

Reply #21 – May 10, 2021, 12:35:16 pm

Why no mention of keying the maxi's and not needing any hose connection. The tow truck air line doesn't apply brakes as our towed's do. I would even key them myself if the driver didn't want to.

Re: Wet tank, no purge valve

Reply #22 – May 10, 2021, 12:55:08 pm

Quote from: craneman – May 10, 2021, 12:35:16 pm

Why no mention of keying the maxi's and not needing any hose connection.

"Keying the maxi's" I assume means manually releasing the spring brakes? That is not necessary because you need the outside air pressure source (from the tow truck) to pressurize the air suspension components. You don't want to take a chance on the air bags deflating during the tow. You might as well also use that outside pressure to release the parking brake.

Of course, if the malfunction that necessitated a tow involves some massive failure of the air lines going to the brake system, then it may indeed be necessary to "key the maxi's".

Re: Wet tank, no purge valve

Reply #23 – May 10, 2021, 12:58:12 pm

Quote from: Tom Lang – May 10, 2021, 12:13:34 pm

where should the air line be connected on my 2003 U295? I always thought it was the air coupling in the passenger side bay with the propane tank and fuel tank.

On my '03 there's a check valve that prohibits air being injected through the coupling you describe.

Re: Wet tank, no purge valve

Reply #24 – May 10, 2021, 01:02:18 pm

Quote from: Travelin' Man – May 10, 2021, 12:58:12 pm

On my '03 there's a check valve that prohibits air being injected through the coupling you describe.

I think this is true on many newer model coaches. In that case, the mod mentioned by oldguy (Reply #18) would be appropriate. It has the advantage of running the outside air source through the coach air dryer.

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