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Old 12-19-2018, 07:16 PM   #1
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Blue Bird TC2000 air bag regulator leaks

Hi. My bus takes about 5-10 minutes to reach 120 PSI from drained empty air tanks. High idle was on, at 1100 rpm. It has a front, rear, wet and aux tank.
Is this normal?

I started hunting down the air leaks and found one fitting that leaks, a shrader valve that leaks but the majority of the leak is from the front air bag auto levelers.

Does anyone know what the part number for those is? Should i replace them if they leak air? Can I just delete them and run a air bag system like on pickup trucks? Where you fill it and leave it alone?

My goal is to just loose less air, and also allow the bus to stay level rather than drop down after 2 hours sitting.
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Old 12-19-2018, 10:48 PM   #2
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unlike a pickup truck system, the air ride on the busses is actually the springs.. its not just air shocks that add level or capacity.. im not as familiar with the fronts.. but on the rears there are no springs.. the "bags" are called air springs.. the leveller valve keeps the bus level regardless of load... this also increases capacity as it adds more air to the springs when that section of the bus is loaded heavily..

5 minutes or more to pump up 3 tanks and the 4 air bags and lines to 120 PSI cutoff is pretty reasonable.. there are bleed down standards to follow as far as when you shut it off how fast does it drop down..

finding air leaks is oretty straightforward.. for one, if your bus was a school bus and had air stop-arms, stop signs, or crossing arms, then delete and cap off all the air lines for those old accesories..

if you hear hissing from a levelling valve and no one is walking around inside the bus.. and there arent significant temperature changes going on.. then replace the valve..

if you njotice the bus drop slightly and the valve opens and adds more air, then it drops a little, repeat cycle, then its time toi pressure test the bags.. I had a couople very small leaks in the bags of my carpenter... they would go flat after an hour... replaced both bags and now that bus takes overnight or longer for the bags to go flat..

the suspension on my red bus was perfectly tight and wopuld hold air for a week or more until I noticed its valve is leaking now so i need to change that out... its minor so it waits for warmer weather!

keep in mind lots of motion inside the bus, which causes it to drop down when you walk into an area.. then raise up when you walk out, will result in the air valve doing a fill and purge.. anbd will run you out of air ... down to the protection valve.. properly installed air bags are behind a protection valve which shuts off air flow to the bag systems and other accessories at below 65-70 PSI.. if your air gayuge is dropping to 0 in a few hours.. then you have a leak in the main air system to solve first... dawn liquid mixed with waster in a spray bottle is a great way to scope for leaks.. run the bus up to pressure, shut it down, crawl underneath and spray everything looking for bubbles... kids bubble solution also works good for seeing leaks....

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Old 12-19-2018, 11:18 PM   #3
Almost There
Join Date: Oct 2018
Location: Ogden utah
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Year: 2002
Coachwork: Bluebird
Chassis: Tc2000
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Christopher, that is excellent information. Thank you so much for the clear explanation!

My bus looses pressure to 60 psi quite quickly, will stay at 60 for a few days but eventually loose all pressure.

There are no longer any arms or stop signs on the bus. These were previously removed and appear to be capped well as I didn't hear any hissing from those areas.

The set up of the TC2000 FE is a rear leaf spring system, with no rear airbags, and only front airbags.

Indeed when the bus is level and no-one is walking around inside I can hear both airbag valves leaking, and can see bubbles when spraying the tube that comes from the bottom of the valve. ( Curiously when I turn the steering wheel the hissing stops in one of the valves.

Beyond that I can hear hissing, and see the bubbles from this schrader valve that is hanging out in the tank dump box outside the driver side of the bus.

Spraying didn't turn up any other leaks.

Thanks again. Where could I track down a part number for those valves?
Would any leveling valve work? Like for example this one off ebay?
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Old 12-20-2018, 09:30 AM   #4
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And to my mind, jack stands are necessary when working under any rig that has air springs. Many can drop low enough to squash you.
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