Foot valve

[Bavo76]

Hi i am Darryl and i have a 1985 Nissan Ud (cma86) .My bus when i brought it had a leaking foot valve so i replace it with a brand new complete foot valve assembly and that fixed the problem for around 5 months but now again its leaking from the foot valve down the bottom .What could be causing this as its a pain in the rear as when i go up the street in my bus i have to hurry back to the bus as it empties the air tanks in around 15 Min's so then i have no choice but to sit there and let it refill ..So what could cause a foot valve to leak so often .I drain my air tanks often so i need help it has the FD6T turbo diesel engine in it .

[somewhereinusa]

That isn't really a bus many here would be familiar with, I would suggest that you talk with local truck/bus shops, it may be a problem with that model. I have had foot valves fail in a short time for no apparent reason.

It may also be something else causing the problem, I did a quick search and found this.
http://www.precisionrebuilders.com/prob1.html It is written for a semi, but you should be able to weed out the part that pertains to a vehicle not pulling a trailer.

I just found some info, that comes from Australia, It is a pdf download that I don't know how to link to. Do a search for

air brakes, recurring leaking foot valve

. In my search it came up at the top of the list It's from a site

www.airbrake.com.au

Dick

[Jive Turkey]

Debris is usually the culprit. After you replace the foot valve I would disassemble the old one and inspect it for what is causing the problem. Inspect the supply line for traces of rust, dirt, oil etc. If you have oil it will more than likely be the air compressor (worn rings). Rust would be something internal like the air tank is rusting out. Dirt could possibly be no air filter or not installed proper A/F. When you go to the parts store I would ask about some kind of filter. There might be a screen or an inline filter that you could install.

[Jive Turkey]

Another thing, if you plan on keeping that bus for any length of time and doing your own repairs I would get a repair manual for it.

[Bavo76]

Looks like this model bus must have a problem with foot valve leaking as its the third rebuild kit Ive put in since owning this bus for 2 years and I am going full time travel start of 2012 so i am getting a bit tired of having to rev up my engine for it to fill the tanks before i can take off and if i need to get out of a place in a hurry i would be bugged.I think a lot of people must think look at that guy sitting there idling his bus for 8 Min's or so every time i pull up and turn off the bus the air is gone within minutes and $80.00 each rebuild kit it hurts the pocket for sure so has anyone put filters each side of the foot valve any photos .And one more thing has anyone built their own air compressor from using their air tanks on there bus photos would be great thanks Darryl

[Jive Turkey]

What have you done with your air system since you have had the bus? What does the inside of the valve look like when you take it apart? Is the treadle valve the only thing that leaks air? If not have you tried sealing up all audible air leaks?