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Air system not charging?
Its been a while since I have started the coach since I have been away with work. When I started it today, it failed to charge the air system. It did however get up to 30lbs but thats it. I checked around the coach listening for air leaks while running , and after I shut down, but didn’t notice anything indicating leakage.
Any advice would be greatly appreciated.
Thank you
Richard
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17 Replies
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Did you try airing the system up with a shop compressor plugged in at the back passenger side engine bay door?
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Not yet, I will gather the necessary items today to accomplish. I was just wondering if there is typically something that normally causes that situation? Thank you for your reply, I will update you after the shop compressor check.
Richard
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30 lbs for brakes or suspension/aux or both?
Clint & Tammy Summers
2000 XL 45 Country Coach (rivets)
1977 FC31 Bluebird Wanderlodge (more rivets)
Vonore TN
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Both systems struggled to get 25-30lbs. But I was finally able to use a compressor to attempt to charge the air system. I could hear air coming from between the rear axles, so since the coach was fully settled with no air reserve, I managed to crawl between the drive & bud wheels and get to the leak. It is coming from the bottom of the air dryer where it appears to have a seam seal? Even with compressor air supply, the air can’t get above 25-30 lbs. I am still researching and studying my approach to the resolution. Does anyone have any advice?
Thanks
Richard
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Need some basic info, What year and Converter?
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86 Lady Liberty 8V92.
It appears to be a Bendix AD-2 dryer, I would like to temporarily bypass the dryer to see if system will charge, is that an option? if so, how would I go about it? The intent is to isolate the issue, and be able to drive it up onto supports to be able to work under it.
Thanks
Richard
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That’s the same dryer i have, do you have a tank up front under the drivers seat? If so fill that tank, with your compressor and see if the air comes up. This will not be filtered air, so watch your moisture.
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I do have a small tank in the compartment below the driver. If I pressurize that tank, will that release the brakes, or just raise the coach?
Thanks
Richard
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On my bus that is one of my Aux air tanks which is suspension, I don’t remember how the lines are checked back to the dryer and brake tanks, I need to look at my schematic when I get home. Do you have an air schematic from Prevost or your converter?
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I believe a PPV just before the chassis aux tank will open allowing a back fill and the chk valves in front of the primary,secondary, and wet tanks are directional towards the tanks.
That’s also what would happen if you were airing up via your aux compressor … right? And if the key is on the norgrens would open allowing complete air up of the suspension.
Clint & Tammy Summers
2000 XL 45 Country Coach (rivets)
1977 FC31 Bluebird Wanderlodge (more rivets)
Vonore TN -
I just got in to read, but today I verified an air connection to the front tank / system, but had to change some of the connections in preparation for connecting the air compressor which is scheduled for tomorrow. Mike, I do have a schematic, and it appears as mentioned by Clint that the lines lead to the airbags and a check valve is positioned at the service tanks that seperate the system from the brakes. If I can get the airbags charged and lift the coach, I can at at get it high enough to block it up to get to the dryer, remove it, and repair the leaks? I will update tomorrow.
Thanks
Richard
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The dryer is fairly easy to remove and repair, just be careful there is a heavy spring to be mindful of. There are tons of videos out there showing how to do this.
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The airbags charged and lifted the coach with no leaking or backfeed through the primary system. After I had the coach lifted, I second guessed myself on the correct jack point or support points to place the blocks. I looked for my reference, but couldn’t locate it, so I am researching it now. I hope to have the dryer out tomorrow.
Thanks, I have looked at several videos regarding the service of it, thanks for the heads up on the spring.
Do you know of a source for filter and gasket sets?
Thanks
Richard
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AD2 dryers were on almost every truck and bus before they switched to a spin on canister style. You can get parts at Prevost or almost anywhere else. online that sells heavy truck parts.
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OK thank you
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Glad you got the suspension air’d up.
I misspoke earlier, airing up FROM THE AUX side of the system (suspension) will not air up the primary side of the system (i.e. the brake reservoirs) due to the PPV valve just upstream of the chassis aux tank. Under normal operation the bus is air’d up from the primary side and when the PPV see’s ~75psi on the supply port it opens the delivery port to the aux system which air’s up the suspension. That in-rush of air to the chassis aux tank is the big whoosh of air you hear when airing up.
Clint & Tammy Summers
2000 XL 45 Country Coach (rivets)
1977 FC31 Bluebird Wanderlodge (more rivets)
Vonore TN
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Thank you Clint.
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