Our bus has the HWH airbag leveling system in it. When parked, air is supplied by a high pressure Thomas 12 VDC compressor located in the steering bay. For reasons I can't understand the geniuses at the factory didn't understand that compressing air (especially at high pressure) creates heat.

That said, they went ahead with using plastic insta-tube to connect the cylinder head with the air leveling system. When you encounter an "excess slope" condition the compressor may run for 20 minutes before figuring out the bus can't be leveled. During that time a tremendous amount of heat builds up at the cylinder head. Enough heat to melt the plastic tubing and blow a pin hole in it. Once that happens the compressor can't deliver air to the leveling system.

I made a copper tubing run to replace the plastic tubing. It's designed to help cool the air before it is passed on to the leveling system. It also allows the compressor to vibrate on its rubber mounts. Some may want to consider this upgrade.


Plastic tubing isn't the correct product for hot compressed air. Use copper instead.

Slide show HERE. (1 frame w/caption)
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