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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: will4104 on April 04, 2014, 11:04:48 AM



Title: Air Line Source
Post by: will4104 on April 04, 2014, 11:04:48 AM
Happy Friday All!

Found a significant leak in my air line on the parking brake system, right behind drivers front tire. Losing about 30lbs when released. I still have around 90lbs when released. I can't see or get to the leak without removing the tire and at this point do not own a jack. It looks like that will be moved up on my wish list... Looks like one of the po's repaired the line in another place with a couple clamps and I don't feel comfortable doing that.

Anyway, question being, what would be the best type of hose and where can I get it? Looks like 1\4 inch ID.

Thanks everyone!


Title: Re: Air Line Source
Post by: luvrbus on April 04, 2014, 11:12:58 AM
Just use the DOT plastic air lines available at Napa or any truck shop  cheap and good stuff


Title: Re: Air Line Source
Post by: Cary and Don on April 04, 2014, 12:02:22 PM
In my opinion, THIS IS NOT SAFE TO DRIVE!

If I was losing anywhere near that much air,  I would not ever drive that on the road.  On the 4107, we could get to all the lines without removing the wheels.  You need to find out exactly where the air is leaking. You really need a manual for your bus.  If you go to Bendix Brakes, they have downloads of how most brake systems work. The parking brake is in the back.

Don




Title: Re: Air Line Source
Post by: gus on April 04, 2014, 02:37:44 PM
90 psi is plenty safe! Original 4104 max pressure was 102psi.

I second the DOT plastic hose, easy to use and connections are push-in type. Great stuff.


Title: Re: Air Line Source
Post by: Oonrahnjay on April 05, 2014, 04:19:35 AM
In my opinion, THIS IS NOT SAFE TO DRIVE!

If I was losing anywhere near that much air,  I would not ever drive that on the road.  On the 4107, we could get to all the lines without removing the wheels.  You need to find out exactly where the air is leaking. You really need a manual for your bus.  If you go to Bendix Brakes, they have downloads of how most brake systems work. The parking brake is in the back.

Don 

     Don, I'm not saying anything about your opinion (I, also, have a very strict view of what's acceptable in my brake system) but I have had a couple of small issues with the parking brake in the plastic DOT line, the fittings, and the hand parking brake valve up next to the driver's seat.  So sometimes, it's possible to have leaks or problems with the parking brake system "up at the front of the bus".

     And I have to say that the $300 that I spent on Bendix brake school was some of the best money that I've spent on my bus; I also agree that the published info on the Bendix website is *very* useful.


Title: Re: Air Line Source
Post by: Cary and Don on April 05, 2014, 08:55:04 AM
The confusion may have been in him saying that the leak was at the front wheel not at any of the valves.  A 30lb drop seems really huge. Hose clamps on a brake line is really unsafe. 

Don


Title: Re: Air Line Source
Post by: luvrbus on April 05, 2014, 09:05:14 AM
You never know Cary duct tape seems to be real popular with some owners of these 50 year old machines I thought the guy had class using clamps just kidding ::)


Title: Re: Air Line Source
Post by: gus on April 05, 2014, 03:23:51 PM
That drop is about normal for an '04, about what mine does.

Remember, this bus originally only used max 102psi and cuts in at 82psi, much lower than newer buses.

60 psi is min for brakes.

There is no need to get dramatic here:)


Title: Re: Air Line Source
Post by: will4104 on April 05, 2014, 05:34:22 PM
To hopefully clear things up, the leak is in the line itself not at any fitting point. The original handbrake was removed at some point and upgraded to air controlled spring brakes. Whoever did this ran the air lines from the side controls area through the floor, tucked up behind inside front wheel area and routed under the bus. Reaching over and behind the wheel, I can feel the leak coming out of the line itself. It's actually blowing out through a split in the line from what I can tell since the air feels like it's coming out in a fan shape. I will try to post some pics when it's repaired in the next couple weeks.

PS Not to worry, won't drive untill repaired

Will


Title: Re: Air Line Source
Post by: Iceni John on April 05, 2014, 09:48:25 PM
When you say that you can feel the air when you reach over and behind the wheel, does this mean that the air line is exposed to all the slings and arrows of everyday driving, let alone any road debris (or worse)?   If so, I suggest either re-routing all critical air lines / wiring / hoses so they're well away from potential hazards, or protecting them inside steel tubes if they have to be anywhere near the tires.

When I ran a propane line up to my generator between the front wheel and the door, I ran its stainless CSST gas pipe inside 3/4" EMT conduit inside some hefty thick-wall seamless stainless tube where it had to run behind the front wheel.   Maybe overkill, but someone else in the RV yard had a blowout that destroyed all his RV's unprotected wiring that the factory had run through the wheelwell  -  it took him many weeks to piece it all back together, so he took care to protect it against any future mishaps by sheathing it in metal.

John


Title: Re: Air Line Source
Post by: will4104 on April 06, 2014, 03:17:28 AM
When you say that you can feel the air when you reach over and behind the wheel, does this mean that the air line is exposed to all the slings and arrows of everyday driving, let alone any road debris (or worse)?   If so, I suggest either re-routing all critical air lines / wiring / hoses so they're well away from potential hazards, or protecting them inside steel tubes if they have to be anywhere near the tires.

John

Unfortunately yes, they're exposed. Not sure why they were run in such fashion. Rest of the line's run through the bays. Will check into rerouting or some type of shielding for sure.

Anyone with a jack, want to come over and play?



Title: Re: Air Line Source
Post by: gus on April 06, 2014, 05:52:34 PM
This plastic is very tough stuff, probably as tough as copper because it is less brittle and not subject to work hardening.

It is also much easier to route so you may be able to reroute yours.


Title: Re: Air Line Source
Post by: wg4t50 on April 07, 2014, 02:34:35 PM
The plastic/PVC/nylon what ever it is, we use it for diesel fuel lines, what we use is rated for fuel also. Bought another 100' of 1/2" today, $1.56 per foot, thought was high, priced at NAPA, was $2.78 ft.  Fittings high too, but beats copper for diesel fuel as copper is not approved for fuel anymore.  EPA etc.
Dave M


Title: Re: Air Line Source
Post by: gus on April 07, 2014, 07:17:10 PM
Those fittings are push in/pull out by hand, no tools needed. Great invention!!


Title: Re: Air Line Source
Post by: Iceni John on April 07, 2014, 07:53:38 PM
Those fittings are push in/pull out by hand, no tools needed. Great invention!!
Just make sure to get DOT fittings with the extended core tubes  -  they're better able to withstand vibration and movement than non-DOT fittings.

John


Title: Re: Air Line Source
Post by: Jim Eh. on April 07, 2014, 08:05:24 PM
The newer style push connect fittings are a blessing during initial installation but over time they WILL seep. Personally I avoid them at all cost on my own vehicles. Use only DOT fittings available at any Truck Tractor/semi trailer supply store or dealer. They all have inserts and sleeves to grip/seal the connection. Do not use them without both components. The air line has two layers with a fabric mesh layer between them for strength. The "fan" happens when the air line is subjected to an impact strong enough to cause a failure. If it is subjected to abrasion, the spot will turn white. If you see white repair or replace that section or put a union at the failure point.
You can also use a DOT union to repair your line at the point of failure. It is an approved repair for highway trucks/trailers so you don't have to replace the line.
It is a wise thing to carry in your emergency kit as well. Different sizes, maybe two of each of the most popular 1/4", 3/8", 1/2", and one 5/8" and one 3/4". It all depends on how old your airlines are.