Automatic Drain Valves

[hogi6123]

So, now that I have the bus up on stands, how hard should you have to pull those to open them? I don't have any cables so I guess I should add them on. Is there a preferred way to do that?

Jim

Another thing... the drains really aren't at the bottom of the tanks, so how much good are they really if they leave 2" of water below them?

Lol I had the same thought.

My valves have rings on them, but they open by pushing not pulling.  It is just pushing against some spring pressure so not very hard.  Pushing or pulling to the side seems to work.

[dtcerrato]

My statement about a good dryer was made because since it was installed no moisture has exited any of my pull cable tank drains. Made a believer out of me. I still pull the manual drains but not as often...

[chessie4905]

Having an air drier should be an essential item anymore on our coaches especially older ones to extend the life of the air brake components. Rusted through tanks are showing up more as our fleet ages. Daily draining helps, but that moisture is still there. Dry air systems are invaluable to avoid freeze ups we read about every winter season here. Nobody wants to spring $300+ dollars on something they feel isn't essential, but should seriously consider.
Btw, if you drain your tanks and see oil, sludge combination coming out, leave tank drains open over night or a couple of days to completely empty the tanks of that crap. Like draining an oil jug overnight. Noticeable amount of oil still comes out.
At the very least, install drains with lanyards. They aren't that expensive, and once installed, avoid having to get under coach. Biggest decision will be to determine the length of lanyard.

[buswarrior]

Re: mci drains up the side of the tank

Up there to avoid road debris snapping them off and disabling the coach.

It is not the outlet location that matters, but the intake location... anyone cut one open?

I was told similar to propane tanks, it has a pipe inside to the bottom.

Happy coaching!
Buswarrior

[richard5933]

Seems like the wet tank on my 4108 drains the same way - the petcock is actually next door by the fuel filler, and the tube that feeds it from the tank has to go uphill a bit. My thought is that it relies on the air pressure to drain the water, so leaving it open overnight isn't going to help.

[chessie4905]

Richard, read your GM service manual. Leaving open overnight better allows oil and slime coating tank to slowly drain. Also, when draining tanks, more water will be expelled at middle to lower pressure than at full psi.

[buswarrior]

Richard, is this "uphill" something added on external to the tank?

Happy coaching!
Buswarrior

[richard5933]

Richard, read your GM service manual. Leaving open overnight better allows oil and slime coating tank to slowly drain. Also, when draining tanks, more water will be expelled at middle to lower pressure than at full psi.

I hear what you're saying. However, the drain lines from the wet tank go uphill to get to the petcock inside the fuel door. Leaving the petcock open overnight isn't going to drain anything that drips overnight - it's just going to collect in the lower portion of the drain tube.

With the liquid collected in the lower portion of the drain tube. It's not going to be expelled until there is enough pressure in the tanks to push it out. Perhaps what I need to do is start blowing the tanks during the pre-trip as well after pressure builds to blow out whatever has collected overnight from dripping down with no pressure?

[richard5933]

Richard, is this "uphill" something added on external to the tank?

Happy coaching!
Buswarrior

Here's a photo...

The wet tank is the left half, the dry tank is the right side. Follow the lines coming out of the drain ports on the bottom of the tank. They go uphill a bit and then terminate at the bulkhead. The petcock is on the other side of the bulkhead and accessed through the fuel door.

Even if I leave the petcocks open overnight, there's no way those last few drops are going to find their way out. Looks to me that the system was designed to allow the liquid to collect in the lower portion of the drain tubes and then rely on air pressure behind it to expel everything out the petcock.

And yes - this is all factory. This is the HVAC bay immediately rearward of the main passenger door. (My batteries are in the rear next to the radiator)

[chessie4905]

Im referring to air tanks UNDER the coaches and under drivers compartment. Since your tank has a valve at the end of the line, any oil will accumulate an the line and be expelled when you open the valve. Same idea, dont you think?Anyway, get an air drier. Keep what you have in better shape.
Btw, my other 4905 has PP valves for expelling any moisture. they are normally closed. Push to expel.

[DoubleEagle]

Thanks for all the comments everyone, I decided to just replace with a Bendix DV-2 as I have an air dryer, and the wet tank is up over the axle behind the wheels, so a manual pull type would be awkward, and it would be hard to see what is coming out. I discovered that the Expello Drain Valve comes in two versions. The first versions were pneumatically activated by a small air line from the exhaust port, and the more recent ones are all electronic. They might be nice, but they are three or four times as much, and are more complicated.

[RichardEntrekin]

I am also a fan of manual drains. I do not like the pull lanyard because they can get debris into them and leak. I put DOT fittings in the drain hole and ran DOT tubing to one of the bays on the coach. I installed 1/4 turn SS valves on the  DOT tubing and clear tubing on the exit of the valve to below the coach.  The clear tubing allows me to see what is coming out and avoid a shower.

I did this for the wet tank, both brake tanks and the auxialliary ping tank.

[HoBoJo Busman]

Thank you for these suggestions on ways for draining the AIR tanks.  Excellent idea.

[Jim Blackwood]

Is the drain valve also a pressure relief?

Jim

[HoBoJo Busman]

I do believe that any time you are draining a tank...to any degree,
you are relieving pressure.