Help Chasing A Leak

[tdelorme]

See if there is a clue here to help me find a small air leak. When the bus is parked at home in the barn, my auxiliary air compressor will run maybe twice in 24 hrs. No big deal and I have been feeling a bit smug about having such a small leak. I've had big ones in the past so the smug feeling is still new to me. Anyway, last week when we were parked at Texas Motor Speedway having those 60 MPH wind gust, I dumped the bags to help stop the bus rocking. An hour or so after dumping the air bags, the aux. compressor kicks on, and started running about every three hours until we left Monday. Back at home, I left the bus parked as normal in the barn with the bags full, road ready. Yesterday, I spent about 8 hours working in the bus barn and the aux compressor never ran at all. So, where should I start looking for a leak that happens when the bags are dumped? Don't say "don't dump the air bags," Jan already suggested that. I've got a leak and I'm gonna find it, so you air bag gurus help me out here. I may go by WalMart and pick up a HectoMatic to start.

[dalej]

Ted, that would be a great place to start.

[Joe Cannarozzi]

I would start at the air manifold in the steering bay and isolate the solenoids for each corner one at a time and also check the 3 port norgren there that works as the exhaust port for the suspension when using level-low.

I am guessing one of those spools is leaking.

Weather or not power is going to them "key on" or not will be relevant. I would assume you had the key off at the track and they remain engaged with it off.

Try dumping in level low then go back to ride mode but immediately after switching back, turn off the key. That would leave you dumped but not give the suspension any time to use to use any air. That will not find the leak but solve your problem of loosing air with the suspension dumped.

[Jon Wehrenberg]

This is just a guess Ted. When you dumped air you exercised the Norgren three port valve on the rear wall of the steer compartment plus the two solenoid operated three ports located on a bracket near the windshield washer fluid tank.

In addition you also exercised the five port Norgrens that control the air flow to the air bags and shut off the flow when the bus is turned off.

Additionally what you did was open all of the solenoid valves located on the rear wall of the steer compartment. Any one of all of these various valves could have failed to close properly with the end result being a loss of aux system air.

You might as well quit chasing the leak right now and wait until the leak is actually happening. It is hard enough chasing a leak when it is leaking, but it sounds like you are chasing a leak that is not leaking. Go have an adult beverage and enjoy the rest of the afternoon.

[dreamchasers]

Ted,

I think Joe is on target. When the dump button is activated, three of the five leveling solenoids engergize, applying pressure to three different spools on the Norgrens. Unfortunately, it will be tough the determine the exact location.

If you dump the suspension and leave the dump switch in the on position, these three solenoids will remain engergized, thus, these three control lines will remain pressurized. If you follow Joe's suggestion of dumping the air, then returning to the drive position, then turn the ign switch off, then you suspension system should return to exactly the mode as to when it is parked and the on board air compressor is maintaining the air pressure. If life is good at this point, then your leak must be in one of the pressured control lines or Norgren solenoid spools. You would never notice the leak while underway, because your engine air compressor would supply a minor leak with no problem.

If their was ever a case to support my 'bubbler', this is one. you could connect the bubbler in series with the outputs of the three energized solenoids, one at a time, and you would surely find you leak.

Below is the link I published last year at Sevierville, with log on credential to the weblink showing how the suspension system interacts.

http://forum.prevostownersgroup.com/showthread.php?t=2116&highlight=airbags

Remember, converter specific changes could determine exactly how your system operates.

Hummm... How far are you from Livingston?

I will PM you.


Hector

[Jon Wehrenberg]

I think Ted has only four solenoids and as soon as he turns the key off his solenoids are de-energized. As soon as the solenoids are de-energized they immediately depressurize the air lines that were pressurized. When he moved the coach he went into the ride position. In that position all three five port Norgrens should have shifted to open the path through the ride height valves, so whatever leak if any there was related to the five port valves, it may have been "erased" by exercising the valves.

I also think Ted has the rear three port Norgrens that dump tag air when the pressure in the aux system drops. I do not know if they were exercised when he dumped air at the race track, but they could also be the source of aux system leaks.

I fully agree with the practice of momentarily going to the drive position on all coaches for an instant before turning off the key.

[rodburtonmusic]

I have picked up so many new words in the short time I've been here...Norgrens...bubblers.

Some of them..I even understand!

Love this place....:eek:

[sawdust_128]

Rod: I hate to break this to you, but those aren't words. They are denominations. Also, few are small.

[Joe Cannarozzi]

Do not think just because you have been over and over and over your bus with soapy water that doing it again is useless.

Today I found 2 leaks that have probably been going on for the duration. One was the passenger seat, automatic ISRI. I have been over this numerous times with the soapy stuff and have never heard or saw anything. Today I put an air toggle in line on it and shut it off to see if it would stay up. The seat went down in about 10 min.:) progress


Next:
Our 8-V is mechanical so I do not know if others have these solenoids. They are located up next to the engine fuse box. 1 is for the high idle and the other is for the Jake.

4564
I have sprayed the fittings on these before but today I hit them very generously all over and bingo it started foaming from the housing itself, and pretty good too.:)

These are supplied by the brake tanks and I never would have guessed. Just by chance I found it while the aux air was open and 0. I have been pulling my hair out trying to find the source for this primary and secondary air loss. I assumed this stuff was supplied by aux. air. I assumed wrong. Our belt tensioner air is also coming from the brake tanks. Go figure. Everything back here is energized off the brake tanks, KEY OFF.

Judging by the size of the leak and comparing it to the time and amount the brake tanks go down this right here is IMO easily the lions share of the loss, possibly all of it, we will see.

4565

I think some celebration is in order, wheres the Morgans:rolleyes: Seriously it really is big to me we have had this tub for over 3 years now and I am suppose to be able to repair them on occasion:o


This is 1 of 2 slave cylinders at the pump that are pneumatic. Here again it is not until I shot it with an overabundance of the soapy mixture that a leak appeared. I have checked here before, more than once.
4566

Something else I learned. I went out and opened the drain cock on the aux tank about half, to give me time to go in the bus and see if it affected the brake air, and IT DID. My primary AND secondary tanks went down with it till they hit 75 where they stopped going down and held. I do not know how long Prevo plumbed them this way but I am sure the new ones will not encounter this.

When I look back on this time without being able to drive I think I will really appreciate the time it gave me to shake things down and make repairs and do upgrades. Dry-dock baby, our stuff is dry-docked. It's a good thing.

[dreamchasers]

Joe,

Good finds. In my mind, rubber is the enemy in our vintage coaches. 99% of my suspension leaks have a leak rubber.

Hector

[dalej]

Joe, I replaced the check valves on each of the brake tanks and it takes care of the leak back. A good way to check the brake tanks is to air the system up, open the wet tank and let it empty out completely. Then put a small balloon on the end of the drain and watch it, if it starts to blow up you know it's coming back out the brake tanks.

[Joe Cannarozzi]

I will try that Dale. Why have I never heard of this test:o

[Joe Cannarozzi]

I pulled this solonoid/air valve. I figured I would try to see if I could take it apart and see if it was saveable.

4574

Turns out the stainless fitting out the top had an old dry o-ring incorporated into it, cracked it comming off. Thing is, it was bubbling nowhere near the fitting. The air was blowing down inside the bell pushing out at that lower seam.

10 cent O-ring:) one more gone.

I am going to remove my brake pedal valve and either rebiuild it or replace it, it bubbles ever so slightly.