Losing Air Pressure. Need Your Advice

[DKO]

I started losing air pressure when at a low idle in traffic while making my way from Ohio to Oklahoma. As long as I was accelerating or idling at 1000 RPMs the pressure was fine.

We came upon several lane closures and slowdowns due to accidents and construction. Each time I would have to pull out of the lane of traffic and allow the pressure to build up before continuing. When I arrived in Oklahoma and turned off the engine I could hear an air leak on the passenger side of the engine.

Down near the bottom center of this picture you can see the two metal mesh type hoses. The small one going up is the oil hose the large one going side to side toward the right bottom corner is the main air hose coming out of the compressor. These are special high temperature hoses with Teflon lining.
As you can see the small line is fastened to close to the air line allowing them to rub. Each of them has a hole. (Although I did not realize the larger hose was leaking until later) I was able to have the small hose spliced with a special coupling by Hose Specialties in Ardmore, Oklahoma.



The large hose isn't so easy. It is an air hose that feeds from the compressor toward the front of the bus and out of sight. It looks like it goes all the way in front of the drive axle without a junction. That means there is no way I can access it to remove it, replace it or splice it without a lift or pit.

It is also the special high temp hose with Teflon lining. Is it possible to have a coupling put in? The small hose coupling was put in place by press on a bench. There may be a more portable way to press the coupling in but I have no way of knowing. The hose specialty guy isn't open again until Tuesday. I didn't ask him on Friday because I didn't realize at the time that the air line also had a hole.

A friend that was helping me wrapped the air line with a rubber patch and put a hose clamp over it... In this picture you can see that temporary fix and the coupling in the small hose.



Both of us were dubious about the effort to stop the leak but believe it or not... It worked! I needed to go about 150 miles today and it held pressure until I arrived. While I was parking I began to lose pressure again and when I turned off the bus I could hear air escaping again.

Any ideas? Keep in mind that I cannot get the hose off without a pit or lift. I am wondering if this hose can be repaired without removing it. Any help would be appreciated.
Thank you in advance,

DKO

[Ed-Sommers]

That patch job is fine but needs to be longer. Find a longer piece of rubber hose whose ID is the same size (or slightly smaller) as the OD of ruptured hose. Slice hose length wise, not to get two halves, but to allow patch hose to cover rupture. Put wide hose clamp over the area of the hose where leak was detected with soaped water, and at least one on each side of that clamp.

Done!

Ed

[Mike Canter]

DKO we use these braided steel teflon lines a lot in drag racing for both brakes and nitrous lines. The teflon lining is for high pressure and not for high temperatures. Most hydraulic shops have the tools to make them but they sure hate to repair them because of the libility. I would call around to different hydraulic shops in your area and see if anyone is willing to help you. The swedging tool that is needed to put the fittings on is not that big and I have seen portable ones. If you can undo one end from the compressor and pull it out from under the bus so it is easy to get to would help.

What caused the holes to be made in these lines?

Braided Teflon Hose - For racing car & boat engines
Teflon ® Hoses
Russell Performance - Nitrous Lines

[tylerdmoore]

Okay...going to add my 2 Cents here as I feel this one is a serious safety issue. That air provides coach brakes. That leak you have will continue to get worse. Now, imagine yourself driving down the center lane at 60 when it ruptures.....Parking brake sets, coach comes to a very fast stop in the middle of the road...cars piling up behind it. Bottom line, you don't have enough insurance for this one!

It will certainly be a PITA to get that line out of there, but that's what should be done...full replacement. If needed, you can use standard high pressure air hose with Ferrell style fittings to get you by while you get a braided replacement made. A good parts house like NAPA can get you all set up with the temp hose and provide good advice on installation.

BTW, I have 10' of this hose and a bag of misc fittings in the basement of the coach for just this type of issue

[DKO]

Thanks guys,

Mike,

I called them high temp hoses because that is what Hose Specialties in Ardmore, OK that fixed the small one called them as did Prevost in Ft. Worth. Perhaps they are both high pressure and high temp. The hole was caused by them rubbing together. The small one was fastened too close.

tylerdmoore,

Thanks for the precaution. A great hose guy at NAPA wouldn't touch it. He said the air coming off that compressor is very hot and nothing but a Teflon lined hose will do it.

DKO

[DKO]

Quote:

Originally Posted by Ed-Sommers That patch job is fine but needs to be longer. Find a longer piece of rubber hose whose ID is the same size (or slightly smaller) as the OD of ruptured hose. Slice hose length wise, not to get two halves, but to allow patch hose to cover rupture. Put wide hose clamp over the area of the hose where leak was detected with soaped water, and at least one on each side of that clamp. Done! Ed

That will probably be my next step so I can limp some where to get it replaced.

Thank you very much.

DKO

[tylerdmoore]

Yes, it's not an ideal solution...but 25 years on the road in heavy trucks does teach one what can safely be done to get you to that true repair shop 20-30 miles down the road. When it comes to the mechanical aspects of the coach I feel VERY well in control....all that other shtufff....errr, still learning

[DKO]

Quote:

Originally Posted by tylerdmoore Yes, it's not an ideal solution...but 25 years on the road in heavy trucks does teach one what can safely be done to get you to that true repair shop 20-30 miles down the road. When it comes to the mechanical aspects of the coach I feel VERY well in control....all that other shtufff....errr, still learning

I do appreciate the voice of experience. I am totally out of my league and getting further behind all the time. Thank God for grace and people willing to help.

DKO

[freebirdbus]

Hello,
Yes, those hoses can be repaired in place. It is not uncommon for metal braided line to fail if allowed to rub against another metal braided line. I have used and made up my own metal braided lines for over thirty years. One simple solution would be to cut the lines at the failure points and add a splice fitting or a pair of fittings to each line. Done. Next, look carefully along the length of each line. Cover the line with a short section of rubber hose anywhere it can rub or abrade. Secure the hose in place with a zip tie.
Happy motoring!

[DKO]

Quote:

Originally Posted by freebirdbus Hello, Yes, those hoses can be repaired in place. It is not uncommon for metal braided line to fail if allowed to rub against another metal braided line. I have used and made up my own metal braided lines for over thirty years. One simple solution would be to cut the lines at the failure points and add a splice fitting or a pair of fittings to each line. Done. Next, look carefully along the length of each line. Cover the line with a short section of rubber hose anywhere it can rub or abrade. Secure the hose in place with a zip tie. Happy motoring!

Are you referring to the Teflon lined hoses or just regular metal braided hoses? I have every reason to believe this hose is Teflon lined.

DKO

[KIX]

You mentioned that you need a lift or a pit to be able to access the hose for repair. Consider making a "ramp" from 2 x 10 (or 12") lumber. You can put several pieces together to raise the rear of the coach 6 to 9 inches. And it would be safe. Just make sure you chock the wheels so it can't roll in any event.
Even if you have to buy a saw to make the cuts it would be cheaper than not getting it fixed.

[DKO]

Quote:

Originally Posted by KIX You mentioned that you need a lift or a pit to be able to access the hose for repair. Consider making a "ramp" from 2 x 10 (or 12") lumber. You can put several pieces together to raise the rear of the coach 6 to 9 inches. And it would be safe. Just make sure you chock the wheels so it can't roll in any event. Even if you have to buy a saw to make the cuts it would be cheaper than not getting it fixed.

A possibility I have considered. I probably have enough wood with me to get one side up several inches but I am not going under there. I am a big boy and big boys have no business in some places.

[freebirdbus]

Quote:

Originally Posted by DKO Are you referring to the Teflon lined hoses or just regular metal braided hoses? I have every reason to believe this hose is Teflon lined. DKO

DKO,
I do not know what you mean. In all metal braided hoses, the metal braid is an external shield to the rubber/fabric/liner assembly. It shields from external damage and controls/limits swelling in the event of a casement failure. Some hoses use PTFE or Teflon liners. They are used in motive and food service applications, some with working pressures in the thousands of pounds, much higher than the working or maximum pressure of a brake air line system on a coach. I would determine the dash size of the lines and repair them as long as the rest of the hoses are in good condition. Or, unbolt them, take them to a supply house that builds hoses, and have replacements made while you wait. Your coach, your hoses, your call

[Mike Canter]

High pressure teflon lined hoses have to have the fittings swedged on. You cannot use just a push in AN fitting that you tighten with a nut like with regular rubber lined steel braided hoses. The teflon lining does not allow the standard push on fittings to grip under high pressure. Not sure about the your coach and your call. I am sure that there is a federal/DOT standard for air lines on a vehicle with airbrakes and that will also say that they require a specific type of connector. It might even specify that it has to be a one piece hose with zero splices in it and that is why it is the way it is on your bus. There should be somebody around that fixes airbrake systems on trucks that you can get to advise you.