Clicking until air purges

[jimmyz]

This may not be an engine problem but since is happening on a monaco 2007 with a isb I will post it here.When I start the engine and let it idle to warm up I start to here a ticking that you would swear was a lifter noise.It starts to get fairly loud and just as I start to worry that I have a problem the air dryer purges air and the ticking is gone.just kind of wondering if anyone out there is familiar with this ticking and think I need to look at my air pump or dryer I would appreciate any info I can get.

[twinboat]

Air compressors are 2 cylinder piston pumps. While filling the air system they are under load. It like an engine with crankshaft, pistons and connecting rods.

Once the air pressure reaches the set point, the governor sends a signal to the dryer to unload ( blow off ), and the compressor valves to be held open, letting the compressor spin with no load.

You may be able to re-create the ticking sound, by pumping the brakes to get the pressure down low enough to start it pumping again.

All compressors make some noise but I suggest you have an experienced mechanic listen to it.

It could be knocking due to bad bearings. I have also heard them clack pretty loud because the spline in the drive was wearing out.

It may only be a slight air leak, leaking on every piston stroke. Once the system unloads, there is no air pressure between the compressor and dryer.