Location of Air Tank Drains

[Stolaas]

I am trying to sell my 81 MCI MC-9 and last month it aired up fine. There was a little spittle from the tank but stopped. Today, after it was cold the past few days, I cannot get the bus to air up at all.

I turned the front wheels and can here where the air is spitting from and have taken a picture of it.

We're are the drain valves on this bus (with pictures)? And what/why am I hearing the air spit out of the bottom of this tank?

What is the fix?

I can't get under the bus...

[Dave5Cs]

Use a long stick and reach in there and try taping the bottom of the middle to try to close the purge valve on it. That is your Air dryer. on the wall behind it if you look the other way you have to tanks that hang down and should be a drain on each but that is coming from the bottom of your airdryer. It opened and cant shut because it is stuck open or has something keeping it from closing and building up air like rust if you have never drained the tanks. HTH

Only other way is to jack her up and support it with heavy duty jack stands or wood blocks and take off the bottom of it (AD2 its called) go to a Napa store and get a purge valve rebuild kit and new Desiccant filter cartridge.

[buswarrior]

Whether whacking it works, it will fail again shortly.

It needs the replacement of the purge valve, and be sure to get the model with the 24 volt heater in it, and get the wire properly attached and powered.

It freezes stuck in the cold otherwise...

Where are you? Another busnut may be nearby?

Happy coaching!
Buswarrior

[Dave5Cs]

You can buy the Purge valve ( it just unscrews from the bottom plate)with out the bottom plate, just check the heater wires to make sure you have 24VDC on the wire when key and or heater is on in the coach then let it run and see if it is hot on the box with the wire attached. That was just to see if it works and you can air it up and if so Like BW said get the rebuild kit because it will do it and soon again but if the heater works you don't need to put out the money for a whole bottom plate.

[buswarrior]

The air drier heater is powered via the coach heat switch.

There is often an inline glass fuse holder stuffed into the outside driver's electric box that is involved too. 3 amp IIrC?

Coach is for sale? Minimum effort and expence is going to be expended here...

Happy coaching!
Buswarrior

[lostagain]

Isn't the air dryer heater on a thermostat? Like it only stays on when it's cold out?
Rebuilding the whole dryer is cheap and easy. Desiccant cartridge and purge valve are less than $100 at the heavy trucks parts stores. It is preventive maintenance that is necessary to insure trouble free travel in the winter.

JC

[luvrbus]

Isn't the air dryer heater on a thermostat? Like it only stays on when it's cold out?
Rebuilding the whole dryer is cheap and easy. Desiccant cartridge and purge valve are less than $100 at the heavy trucks parts stores. It is preventive maintenance that is necessary to insure trouble free travel in the winter.

JC

Yes the thermostat is set to come on around 40F lol when they work

[buswarrior]

Thermostat is built in.

The way MCI wired it, thru the coach body heat switch, means it only sees power if the coach interior needs heat.

Busnuts often screw this up during tear out, remove their coach heat, never turn the switch on, and freeze the purge valve.

Yes, a full service of this drier is obviously overdue... not likely going to happen if a low post count busnut is trying to sell the coach...

Happy coaching!
Buswarrior

[PP]

Thermostat is built in.

... not likely going to happen if a low post count busnut is trying to sell the coach...

Happy coaching!
Buswarrior

That's brutal...    FWIW-thermostat is supposed to kick in at 38° F-don't ask me how I know.

[Stolaas]

Thanks everyone, have had this coach for about 12 years and never got to use it after finishing in. Too many kids came (4) to go out in it.

I'm super cautious about getting under the buss...  how do you drain the tanks without getting under the bus? If they are supposed to be drained daily certainly doesn't make much sense to have to get under the buss to do it....

One of those things I wish were posted everywhere like "diesel fuel only) 🤦🏼‍♂️

[Dave5Cs]

Put auto drain on each tank, pretty expensive or like I did get the cable pull 1/4" drains to replace the manual drain-cock valves. You can get them on line but you will have to get under there to install them but will anyway to fic or rebuild your air-dryer.

https://www.amazon.com/Midwest-Control-DP25-Degree-Temperature/dp/B01KO7CNW6

[bevans6]

The only two tanks that are hard to get to are the parking brake tank (passenger side front wheel well) and the wet tank (driver's side).  When I started I used what I later found was a fifth wheel pull stick to reach under and pull on the loops on the drain valves.  Later I installed new cable pull drain valves and routed the cables to inside the fuel fill hatch.  The tank that really needs daily draining when operating daily is the wet tank.

[eagle19952]

IMO Auto drains are....stupid.
They fail.
With cable pull drains, it takes no time at all to know they have been drained, and you get to walk around your bus, something you're supposed to do.
Who doesn't do walk arounds...
People with out cable pull drains.

[buswarrior]

Ditto.

A busnut needs to watch what comes out, looking for "regular"

Auto drains leaves the busnut blind as to developing problems.

And, they stop working. How will the busnut know that?

A busnut is owner, financier, mechanic as well as driver.

Ignore what your rig is trying to tell you, at your peril?

Happy coaching!
Buswarrior

[Dave5Cs]

Thats why I said "I put cable pulls on mine"