Bus Building pressure on gauge, But no air to system?

NewbeeMC9 · March 17, 2018, 06:27:54 AM

Good Morning,

Did a search and found a similar issue on the other board, but no resolution yet.

Anyhoo. Bus is in storage but need to get it out soon, air system airs up on gauge, dryer does not purge(AD-9) and the pressure can be brought down by cycling the service brakes, park brakes will not release, moved it by applying air to the towing air port to keep brakes released.

I think it is PPV and will order one and replace anyway, can't seem to find where it is, also may be a check valve, trying to figure out from the manuals, but old copies are tough.

Here is the valve Andy Posted.

Part Type: Air Valve
System: Air
Part Name: Pressure Protection Valve
Part Description 1: PR-2 Pressure Protection Valve, 65 psi
Manufacturer: Bendix
Mfr. Part Number: 277147
Vendor: NAPA
Part Number: TWD BENOR277147X
Cost: 41.85

https://www.napaonline.com/napa/en/p/TWRBENOR277147X

Have new cartridge and purge valve for dryer to service while I'm under there.

Any Help with this or experience or pics is appreciated.

buswarrior · March 17, 2018, 06:47:18 AM

More than likely, the fittings will benefit from some penetrating oil, prior to removal attempts.

Proper stuff, NOT WD40...

Commercially available preparations or home brew. 50:50 transmission oil to acetone has been raved about for decades by those who have concocted it.

Get a copy of the coach air schematic for your maintenance log, and mark the repairs. Then you have the history of known and unknown...

Happy coaching!
Buswarrior

bevans6 · March 17, 2018, 07:25:55 AM

On my similar year MCI (if you have an MC-9, that is) the PPV is mounted on the emergency brake tank, which is the passenger side tank between the front wheels. There should be two things mounted there - the E-filter and the PPV. The feed to the governor is after the PPV so that would explain the no-purging, and the feed to the emergency tank is also after the PPV, so no air to release the parking brake. Also no air to the suspension or accessory systems, which include all of the engine air systems.

chessie4905 · March 17, 2018, 07:58:40 AM

Penetrating oil doesn't help when removing pipe fittings. Anyway, most fittings on our coach are brass, so they don't rust fast. They are sealed with pipe sealing compound. This stuff can get pretty hard over the years and make it difficult to break loose fittings. If you encounter this, especially on larger ones, heat threads with propane torch some. It will soften sealant and assist in removal.

buswarrior · March 17, 2018, 10:34:23 AM

No, but penetrant can help with the pipe-to-fitting bond.

The whole pipe will twist with the fastener.

That is what one is trying to moderate.

Happy coaching!
Buswarrior

eagle19952 · March 17, 2018, 10:40:40 AM

Quote from: chessie4905 on March 17, 2018, 07:58:40 AM
Penetrating oil doesn't help when removing pipe fittings. Anyway, most fittings on our coach are brass, so they don't rust fast. They are sealed with pipe sealing compound. This stuff can get pretty hard over the years and make it difficult to break loose fittings. If you encounter this, especially on larger ones, heat threads with propane torch some. It will soften sealant and assist in removal.

does if there is teflon tape...which goes there. dope is for gas pipe.

bevans6 · March 17, 2018, 11:31:36 AM

Most hard lines that I have on my bus terminate in a 45 degree flare fitting onto a flare to pipe thread adaptor that goes into the casting of the thing you are connecting to - the filter, the PPV, the whatever. As BW says it's real common to have the steel line rust where it it goes into the flare fitting and rotate with the flare fitting when you try to turn it. I've had some flex lines that were pipe on one end and a flare fitting on the other, but those are a PITA.

Dave5Cs · March 17, 2018, 02:06:07 PM

Quote from: bevans6 on March 17, 2018, 11:31:36 AM
Most hard lines that I have on my bus terminate in a 45 degree flare fitting onto a flare to pipe thread adaptor that goes into the casting of the thing you are connecting to - the filter, the PPV, the whatever. As BW says it's real common to have the steel line rust where it it goes into the flare fitting and rotate with the flare fitting when you try to turn it. I've had some flex lines that were pipe on one end and a flare fitting on the other, but those are a PITA.

careful with the heat too if you have nylon or plastic lines. They melt very fast.

Sent from my SM-N920T using Tapatalk

NewbeeMC9 · March 17, 2018, 02:14:21 PM

Quote from: bevans6 on March 17, 2018, 07:25:55 AM
On my similar year MCI (if you have an MC-9, that is) the PPV is mounted on the emergency brake tank, which is the passenger side tank between the front wheels. There should be two things mounted there - the E-filter and the PPV. The feed to the governor is after the PPV so that would explain the no-purging, and the feed to the emergency tank is also after the PPV, so no air to release the parking brake. Also no air to the suspension or accessory systems, which include all of the engine air systems.

I guess I should clean out that e-filter as well, or is it a replace or replace inners sorta thing?
?

chessie4905 · March 17, 2018, 04:23:22 PM

Every factory fitting on all my GM coaches use pipe sealant, not teflon. Always hold fitting while loosing attaching line.

buswarrior · March 17, 2018, 06:23:03 PM

The E filter... damned if you try...

If there has been no evidence that it is obstructing air flow...

Maybe let sleeping dogs lie?

Happy coaching?
Buswarrior

eagle19952 · March 17, 2018, 06:32:04 PM

Quote from: chessie4905 on March 17, 2018, 04:23:22 PM
Every factory fitting on all my GM coaches use pipe sealant, not teflon. Always hold fitting while loosing attaching line.

must be vintage

NewbeeMC9 · March 19, 2018, 02:56:50 AM

Quote from: buswarrior on March 17, 2018, 06:23:03 PM
The E filter... damned if you try...

If there has been no evidence that it is obstructing air flow...

Maybe let sleeping dogs lie?

Happy coaching?
Buswarrior

Good morning, I guess it has always been slow to air up, only bus I've ever had, so not sure if that was normal.

What might s sign be? And why leave it alone if I'm changing the ppv out anyway?

buswarrior · March 19, 2018, 07:46:12 AM

If you can get the E filter apart without damage...

The PPV is mission critical, fool with that first, decide about the E-filter based on that experience.

Fast/slow build up... try a test:

Assuming a leak free system...

Build to cut-out, whole system full
Reduce air pressure below 85 lbs
Time the race to build 85 to 100 lbs, engine just idling, no throttle, no high idle.
Under 2 minutes is a pass in this jurisdiction.

A dual system in good shape will rip that off in 45 seconds or so.

Happy coaching!
Buswarrior

Dave5Cs · March 19, 2018, 07:49:01 AM

Oh trust BW on this one. I opened mine up then took out the old probably original string filter which fell apart. Call Luke and had him send me one. Then when putting the darn thing back together could not get it to seal again. took it back off and tighten it up. The corner of it broke off. Tried JB weld and other things. Nothing worked so It is laying in pieces somewhere between here and the other 4 acreas of field by it. I went to parker and got another very much newer filter housing with small filter in it and ran copper lines up to the tool bay in front and put the filter there so I could drain it easier.