[joel]

my 65 MCI 5a had a front and rear pull drain which we drained every couple days of running.

So on our coaches, older XL’s there are drains front and rear which allow us to drain the tanks manually,

my friends with Liberty and CC , etc, builds have button fired solonoid drains I think.

But its in the book I downloaded from somewhere for Le Mirage XL….if I can upload it to the group I will,

but feel free to email and I’ll attach the pdf file to you. It an operators manual, it where the schraider valves, are

and air filters, original little gray coffee filter type unit obsolite. So Prevost put in a Norgren replacement.

SO in steer compartment and rear curbside engine/battery area there are 2 drain points.

Jonathan Fine / Lone Pine, Ca.

“Fool’s Paradise”

97 XL 40 Royale #201

---

1999 XLV X-6872,  liberty #440

[Roscoeapproved]

I have no clue why the designers of the coach do what they do, but I can offer a couple of opinions that will be worth every cent you pay to read them.

Our tanks and their drains are in places where they are protected from potential damage. I think it is valuable to not have a lanyard or a drain extension routed in such a way that road hazards can be kicked up and potentially damage or break something due to the critical nature of the air systems.

But as a second thought we do not need to drain tanks as often as one might think. If the air dryer cartridge or dessicant is replaced to a reasonable schedule (I’m on a 2 year schedule based on my coach usage) it is unlikely moisture is ever going to enter the tanks. I drain my tanks every 5000 miles when I am under the coach doing a service and I get nothing from them. I am basically not draining them with the expectation of finding moisture, but as a means of verifying my protection valves and check valves in the system are functioning properly.

What is often overlooked is our coaches have or should have a water trap at the least between the aux compressor and the accessory tank. When the aux compressor runs that trap should be capturing water before it can get into the accessories or the accessory tank. Typically those traps are in the steer compartment and it is not required to get beneath the coach.

---

Jeff and Lindsay

91 Marathon XL

[Tim]

Jonathon, Thanks for the offer to send that file and the info that this is a feature that some converters incorporate. I will not need the file. My air seems to stay dry. If at some point I discover accumulation between service intervals I will add simple NC solenoids directly to the tanks with switches in a bay. I would probably use those ones with the safety cover that flips up like race cars have for nitrous injection. For now I’ll stay with KISS.

[Jonathan]

Jon, Thanks for you usual thorough and insightful answer. I will be adding a water trap to my aux air per your suggestion. I do get accumulation in that tank while using the coach.

[Archived]

A tech at Prevost service told me that if I wanted to empty the tanks that can only be reached while the coach is in the air, he said just empty the ride height to the lowest level as that will empty (purge) the tanks.

Mark

[Roscoeapproved]

Interesting tidbit…

---

Jeff and Lindsay

91 Marathon XL

[Per]

Interesting Mark. My concern with that would be that just emptying the air from the air bags does not drain the accumulated moisture from the bottom of the tank. Beside that, dumping the suspension does not drain the primary and secondary tanks because of the protection valve. Jon or other experts please flog me if I am misinformed or am misinterpreting how this works.

[Jerry]

Mark, the vintage Jeff has does not have the “ping” tanks associated with the suspension. but more importantly the tech that told you that is misleading you and may in fact not even know what he is talking about. More later.

Jeff, going to the trouble to add some sort of drain device or system is counter productive. I say that because if you are maintaining the air dryer it is going to keep moisture from going downstream. As the engine driven compressor ages however you are going to experience shorter intervals between dryer service because a worn compressor passes oil and the oil coats the dessicant which reduces its ability to retain moisture. But you do not have to guess at that because your coach will tell you by virtue of seeing oil around the dryer purge valve up on the frame of the coach. Any competent tech should notice that when servicing the dryer and give you a heads up regarding possible compressor replacement. The fact you are not getting moisture all but eliminates the need for frequent tank draining which if done at every service when there is access to the underside is easy.

Adding devices to remotely drain tanks is adding potential issues with leaking, either from greater exposure to road hazards or just from leaky fittings or valves.

Mark, Before you ever get a drop of water in any suspension or house components you first have to get it in the accessory tank, and then in such quantities as to start getting it carried through the system, If it reaches that point you have got water in the ping tanks, air bags and all the other valving associated with house and Prevost accessory systems and your American Express is about to get a major hit. As long as you never get moisture from the accessory tank when the techs are servicing the coach leave the suspension and ping tanks alone. If you do drain air from the ping tanks, make certain the suspension is already at it lowest level or the chassis is fully supported because bleeding air from the ping tanks is also bleeding air from the air bags and unless the air bags are already collapsed, the coach is going to come down.

[Archived]

Have checked the tanks several times in the last year, latest a couple of months ago–no water in the tanks.

[Archived]

Thanks guys. It’s pretty easy not to sweat the small stuff. The challenge is figuring out what actually is “small stuff” I have more clarity on this now.

[Archived]

The Tech may have misunderstood my question giving me the wrong answer.

Mark

[Per]

There will be no auto drain of any kind on the Primary and Secondary brake tanks and can only be drained manually. That tech was either out to lunch Mark or misunderstood and was talking about accessory air.