-
low air brake pressure
My 91 prevost only builds 95 psi at fast idle and only goes to 120 at higher rpms.
Air dryer filter has never been changed to my knowledge. Is this step one?
then what is next?
-
5 Replies
-
Air dryer
Pressure governor
Get gunk out of tanks if air dryer has never been serviced..they are likey full of water and debris
Check unloader valves in compressor if none of the above work
-
I answered the other post first but see Mark has given good answers. I want to emphasize one that he mentioned. If you really have a bus with an unmaintained air system you could be in a world of hurt. So obviously get every tank drained, get a new element on the dryer. Check what Mark has pointed out.
If in fact you have copious amounts of water or moisture in the system get it out. It will not be simple or cheap unless you do your own work. And if the system is loaded with moisture you can almost bet all the air valves on the coach are going to be a future service issue and you will have problems that will make a grown man cry.
-
can you tell me what kind of dryer is on a 1986 Prevost air brake system (replaceable canister, …..). When my coach starts and the compressor builds air pressure in the brake system it has an air release that discharges a blast of air as it reaches max pressure. Does this not keep the braking system free of moisture?
-
I know that the air dryer that is (was) on my ’88 is no longer made so it is no longer servicable. I had WW William replace it with the current unit so I would not have future issues. It needs to be serviced at regular intervals but there seems to be some disagreement as to how often that is. I have heard as often as once a year and as much as once every 100,000 miles (pretty sure that’s wrong!). The pressure relief you hear when the compressor tops out will not keep the moisture out of your system.
-
When the air dryer purges (that’s the sound you hear) it is purging moisture caught by the element.
But your air system needs a whole lot more than just having the dryer purge. The element or dessicant beads get coated with oil after a while and no longer will function to remove moisture. Moisture than passes downstream into your pnuematic system. But even if you change dryer elements or dessicant routinely, you still have to drain the air tanks. You have to especially drain the water trap on the aux system if you use your aux compressor.
I suspect a lot of owners who have neglected their air system’s maintenance have ended up spending thousands to repair the damage moisture will do to the coach pneumatic systems.
Log in to reply.