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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: belfert on August 15, 2013, 08:09:28 AM



Title: Am I on the right track for finding this air leak?
Post by: belfert on August 15, 2013, 08:09:28 AM
I seem to have an air leak as my gauges will fall to around 60 lbs or so after the bus sits for a few days.  Am I right to think this leak would likely be on the suspension/accessory side since I am not losing all my air?  It seems to me the pressure protection valve is stopping me from losing more air.  I would think if I was losing air on the brake side I would eventually lose all air.


Title: Re: Am I on the right track for finding this air leak?
Post by: Jon on August 15, 2013, 09:00:58 AM
My knowledge is limited to Prevost, but it sounds correct as you state it. On all three of my coaches if my key was off and my aux air system would drop to zero, my two brake systems would remain fully pressurized, but keep in mind that is the only experience I have with the loss of aux air which is a huge problem for Prevost owners due to the multitude of aux air systems and devices.


Title: Re: Am I on the right track for finding this air leak?
Post by: belfert on August 15, 2013, 11:23:23 AM
Luckily, on a Dina, I have only a few things that use suspension/auxiliary air.  Only the tag axle has air bags.  The step is long gone and the previous owner had just bent the tubes over and tied them shut.  I can't recall if I properly plugged the air for the steps or not.  It may have been only the air for the pneumatic door that I plugged properly.  I'll have to get my diagrams out tonight and dive underneath to look at the air for the steps again.


Title: Re: Am I on the right track for finding this air leak?
Post by: Len Silva on August 15, 2013, 12:14:19 PM
If you are walking in and out of the bus while it is parked, that will use air as the bags try to maintain level.


Title: Re: Am I on the right track for finding this air leak?
Post by: Ralph7 on August 15, 2013, 03:12:39 PM
           You are luckey, mine drops to 60 within min. of engine stop. I cannot hear any leaks. Drops to 30 in 1 hour then empty. 0 to 60 psi fairly fast 60 to 90 sloooooooooow.  Driving/ideling  it goes to 120 and pops off goes to 90 and builds, normal cycle.
          Step on the brakes normal drop.
          I must have all the leveling valves leaking!!!!!!!!!!!!!


Title: Re: Am I on the right track for finding this air leak?
Post by: Homegrowndiesel on August 15, 2013, 06:44:12 PM
"as my gauges will fall to around 60 lbs or so after the bus sits for a few days" OH NO,, A few Days? Must be a problem, LOL. No problem Belfert. I just replaced all of our bags, pancakes, flex lines and still cycle within minutes, No Less Days. All Is Good.


Title: Re: Am I on the right track for finding this air leak?
Post by: belfert on August 15, 2013, 07:30:16 PM
The bus used to be able to sit just about all summer and still maintain 90 to 100 lbs air pressure.  During the winter it would lose all the air.  I'm not terribly worried about it and will still drive the bus the way it is.  My front axle and drive axle have torsion suspension so no air there.  I do have air bags on the tag axle, but no idea if I have a leveling valve.

I went out and looked at the air lines for the steps and I never did remove them.  That is a place to start, but I want to look at my air plumbing diagrams first.  The problem is the diagrams are not in the bus and I misplaced them.


Title: Re: Am I on the right track for finding this air leak?
Post by: azdieselman on August 15, 2013, 07:53:29 PM
My fear would be that after you attempt to fix it, It won't be as good as it is now. Don't ask me to elaborate on how I know this. lol


Title: Re: Am I on the right track for finding this air leak?
Post by: belfert on August 16, 2013, 05:30:59 AM
I found the air diagrams late yesterday evening.  There is nothing at all on the air diagrams about the air step.  There is also really nothing about the air suspension for the tag axle.  There is a line that says 'to suspension'.

I doubt I can hurt anything by tracing back the air lines for the steps and plugging them.


Title: Re: Re: Am I on the right track for finding this air leak?
Post by: Dave5Cs on August 16, 2013, 06:57:59 AM
Brian check the check valve at air dryer to wet tank. One at compressor.they may be stuck open. My system leaks down in 1hour to 0.

Dave5Cs from Galaxy S III


Title: Re: Am I on the right track for finding this air leak?
Post by: Cary and Don on August 16, 2013, 08:42:23 AM
We obsessed over the air leaks on our GM.  It will now drop to about 85lbs after 12 hours with us in it parked.  Takes about about three days to drop to 65lbs if we aren't walking around in it. That was the best we could get.  Then we got to do it all over again with the Eagle.

Don and Cary


Title: Re: Am I on the right track for finding this air leak?
Post by: muldoonman on August 16, 2013, 03:12:03 PM
Old fella told me the only way to find all the leaks in your coach is to drive it in the lake and watch for bubbles. I'm glad all our lakes are dry , cause after spending a lot of greenbacks with Prevost, I would be tempted.


Title: Re: Am I on the right track for finding this air leak?
Post by: belfert on August 25, 2013, 02:18:04 PM
I pulled out the air tubing for the old air steps today.  Two of the lines were no longer connected at the other end, but one line was still connected.  I am surprised it wasn't leaking since it was just folded over and tied shut.  I plugged the connection since it isn't needed anymore.

I doubt this is really my leak down problem since it didn't appear to be leaking before I removed it.  I'm not sure how much more time I will spend on this since the air system works fine under way and meets all DOT specs.