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Engine compartment air bags deflate quickly
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Tom,
thanks for explaining the purpose of the two air inlets. Makes sense. I still have to figure out why the mini air bags don’t inflate with 80psi aux air, just when the compressor on the engine runs. I’m pretty sure they’d use the same line from the aux tank supply.
Maybe a check valve or the regulator is sticking and I need to air up the aux tank to 120psi to free it. Ihave all new belts on the engine and don’t want to start it without having some tension on them.
Gerald
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I think the logic to your mini air bags not inflating from the aux compressor is this;
If your main engine compressor is working properly and the associated air tanks have no leaks, everything is fine and you are good to go.
If that main air system is not good to go, why would you need the air bags for the belts inflated, you should’t/can’t go anyway.
JIM
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To answer your implied question.
The drivers front and curb side rear air fittings are to attach shop air to keep the Prevost part of the coach aired up, as when in the shop or garage if you want to ensure a fully aired up condition.
There are many things that some owners do in maintenance and service where you want full bus air and do not want to run the engine.
JIM
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Yes the aux air supplies air to the engine belt bags. The reason why they should be on the aux versus the main is so you can make sure they are aired up with the aux electric pump before starting the engine. The PO of my coach said he’d start the engine all the time with deflated belt bags and just idle until the inflate. Personally I think the belts should be tight before starting the engine.
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Just so there is no confusion on a very serious issue our coach primary and secondary brake systems are just that. They are exclusively for the brakes and are heavily protected with protection valves and check valves so if either leaks or the aux system leaks one or both brake systems will always have air. The spring brakes (parking brake) are the final and last resort should there be a catastrophic loss of air.
The auxiliary air system is just that. If it is not a brake, it is on the aux system. The typical Prevost chassis has a number of items on the aux system, primarily the suspension, but everything from belt tensioners to door lock to the transmission retarder also shares the aux system. Prevost provides two points with suitable protection for the converters to use for their auxiliary air systems and devices.
A lot of bandwidth over the years has been dedicated to discussions about if belts should be tight when starting the coach. I guess that is personal opinion. One thing is for sure. Seated coaches do not have auxiliary air compressors so it is a pretty safe bet that seated coaches never lose auxiliary air, or they start them with loose belts all the time. If my belts are loose I start my coach. Have been doing that since 1990. So far, so good.
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Using an external air compressor, once the auxiliary air system reached 90+psi the mini air bags in the engine room inflated. That seems to be the threshold the regulator in the engine rooms needs to inflate the bags. I have now a way to start the engine with properly tensioned belts. As Jon points out it may not be that big a deal.
Ok, back to chasing leaks. Good news is that the brake and suspension system seems to hold air well-over a week. I have not yet tried the Level Low system….I understand that can get interesting.
Tomorrow we are off to our first short camping trip. Fingers crossed.
Thanks for all the help
Gerald
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I drove 3900mi in the past 4 weeks and had my auxiliary compressor turned off the whole time.
My engine belts retained their tension for any amount of time that I was parked.
JIM
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