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Author Topic: Losing Air Pressure. Need Your Advice  (Read 3661 times)
DKO
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« on: January 02, 2012, 09:07:44 AM »

1995 Prevost XL with series 60

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.

The leaks are in the two metal mesh type hoses in this picture. The small one going up is an 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 too 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 on it? The small hose coupling was put in place by a 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. Of course now I am 150 miles farther away from Ardmore than I was.

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 yesterday 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.

It occurred to me this morning that there is a possibility that the hose leak is not the major problem and that the system doesn't leak until it is good and warm. But then again it had been running over three hours yesterday before I started losing pressure. Any thoughts on that?

Any ideas on repairing the hose? 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. I am in Blair, Oklahoma and should be here about two weeks. My next route is through Oklahoma City and Tulsa to Neosho, Missouri.
Thank you in advance,

DKO
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1995/96 Prevost XL Vantare
Brassman
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« Reply #1 on: January 02, 2012, 10:19:03 AM »

The fittings on the hose are reusable, IIRC, though the ferrule sure isn't  Angry.

You should be able to buy a length of hose (and some new ferrules), cut the hose, and screw on the fittings. Easy to do, once you figure out how to make a clean cut on the hose.
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robertglines1
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« Reply #2 on: January 02, 2012, 10:44:44 AM »

That hose runs to your air dryer. located in the left rear wheel area.  Just splice it. Your dryer should be mounted on wall of rear bay--outside ahead of rear end. It would be a job to route a new one in with all the clamps involved.  It goes forward down the right side of bus (curb side) then crosses over  just behind last luggage bay at inside floor level then down to dryer.  Simpler to just reroute new hose if you decide to replace it. Steel braided to guard against wear. just a normal hose inside. 150 psi.    Could have been the plastic air line used in rest of air brake system except for it running in area of heat and possible strikes from rocks and rubbing something also more flexible.   Hope this helps.    Bob
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
DKO
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« Reply #3 on: January 02, 2012, 11:55:48 AM »

That hose runs to your air dryer. located in the left rear wheel area.  Just splice it. Your dryer should be mounted on wall of rear bay--outside ahead of rear end. It would be a job to route a new one in with all the clamps involved.  It goes forward down the right side of bus (curb side) then crosses over  just behind last luggage bay at inside floor level then down to dryer.  Simpler to just reroute new hose if you decide to replace it. Steel braided to guard against wear. just a normal hose inside. 150 psi.    Could have been the plastic air line used in rest of air brake system except for it running in area of heat and possible strikes from rocks and rubbing something also more flexible.   Hope this helps.    Bob

That is very helpful. Thank you for the information.

The small hose that I had fixed was definitely Teflon inside and I have been told this one is too because of the hot air the compressor puts out. I know it is hot because I can start the bus for a minute and the clamp is too hot to touch. The engine hasn't even had a chance to warm up yet.

DKO
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« Reply #4 on: January 02, 2012, 01:26:58 PM »

The smaller hoses steel braided are you control and unloader circuits for the air compressor.  Good luck Bob.     
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #5 on: January 02, 2012, 02:50:27 PM »

DKO, Use a abrasive cutoff wheel to cut in place. Then splice a new piece in, or is there enough slack to just cut on each side of the hole? Goodluck
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Tom Yaegle
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« Reply #6 on: January 02, 2012, 03:05:38 PM »


I've made up lots of teflon hoses with the braided SS jacket. If your hose is teflon, as you said, I don't think you can "splice" it. You can cut it it, and place fittings in it to couple the hoses. The braided jacket on the hose is what resists the pressure inside the hose.
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robertglines1
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« Reply #7 on: January 02, 2012, 03:48:23 PM »

There are clamps you really can't access without major headache. I am redoing a 98 that I had to replace all the hoses from the rear bay back and had the floor out of the bus. I know for a fact.  If you can do a fitting repair you are money and aggravation ahead.  If you decide to go the other way there is rerouting to accomplish same results that I can suggest..Many rusted clamps that will have to be cut out  and tie wraps that bundle other air lines that are just about impossible to access from bottom.  I probably have 40 to 50 hrs repairing air system in the rear differential area that was damaged by brake fire.  I do understand it now.  wish I could have skipped that class!  Best wishes   Was your coach a Entertainer? Does it have leveling system?   Bob
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« Reply #8 on: January 02, 2012, 07:34:26 PM »

I would never splice a line anywhere unless it was a temporary, very temporary fix to move a disabled vehicle from a dangerous spot to a safer location for a perminant repair.


Your temp fix was very good you did what you had to to get in.Now fix it right.
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« Reply #9 on: January 02, 2012, 10:45:43 PM »

There are clamps you really can't access without major headache. I am redoing a 98 that I had to replace all the hoses from the rear bay back and had the floor out of the bus. I know for a fact.  If you can do a fitting repair you are money and aggravation ahead.  If you decide to go the other way there is rerouting to accomplish same results that I can suggest..Many rusted clamps that will have to be cut out  and tie wraps that bundle other air lines that are just about impossible to access from bottom.  I probably have 40 to 50 hrs repairing air system in the rear differential area that was damaged by brake fire.  I do understand it now.  wish I could have skipped that class!  Best wishes   Was your coach a Entertainer? Does it have leveling system?   Bob

Thanks for everything, Bob. No, mine was never an entertainer. It was ordered and built at a MH two owners back. We looked at a lot of entertainer before buying this one nearly four years ago. Most the entertainers in my price range had 500-800,000 miles on them. I was thrilled to find this one in that price range with less than 180,000.

DKO
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« Reply #10 on: January 03, 2012, 03:34:52 AM »

Prevo puts MANY MANY hose and tubing clamps right up to both ends of what seems like every line on the chassis and in addition to the clamps ,as far as the plastic air lines go (these are the most fun) they are cut "exactly to the right length.  That makes "there aint noplaying with it" its got to go back exact if the ferral or the end of the line is bad you gotta pull it, or splice it.

When problems occur on your XLS don't think your going to just in and out of there it is going to take some time if you want it to be correct.

Expect each and every clamp fastening screw to be froze they are Phillips heads and usually not easy to get at. They are tight you might cut the old out but forget about pushing the new thru them either.

The clamps are soft so some can be wiggled till broken loose others I cut with side cutters. Then the screws are either hacksawed or ground flush and the plug knocked in with a small punch.

This explanation is what I have learned and now expect any time I know I have to do this. Sometimes you get lucky usually you don't.

Hope this helps Tongue

« Last Edit: January 03, 2012, 03:36:38 AM by Joe Camper » Logged

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robertglines1
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« Reply #11 on: January 03, 2012, 04:32:37 AM »

I know the hose in question and how it runs. If you decide not to splice: to define put mechanical ends on two hose ends after you cut out of short one or two inch damaged area: and use connector. Make sure your new run to the dryer has no sags(place to collect moisture) and is secured well.  Joe is in the repair business and charges $125 per hr I believe and knowing where the original clamps are and routing I would hate to estimate hrs $$$$$$$. If you feel uncomfortable about hose repair; do replace it.. I don't---- I repair hoses that run up to 2500 psi on a regular basis.  Would never repair a line I could get to both end of.    Just for your information. the power steering lines that go to the front are in two pieces. They have a splice at rear baggage bay wall  from differential area. I am replacing them while I have the floor out. There is a mechanical splice there that would be a bugger to get at,  The air hose in question runs above them.  I do not compromise safety and feel confident in repair of any line I would if not I would replace if in doubt. Talk to your local hose guy.   No more from me.   I agree to dis agree.   Bob
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« Reply #12 on: January 03, 2012, 04:50:56 AM »

Might be an opportunity to add a ping tank - make a new hose that is short, to a ping tank in the engine compartment, and cut the old hose at the leak point and attach the old hose to the ping tank with a new termination fitting.  A ping tank is just a vertical 1.5" pipe about 8" long, in and out fittings, and a drain at the bottom.  It catches a lot of the initial moisture and oil from the compressor and lets you drain it out.  All the |MCI's came with one.  Another idea - cut the existing hose section that goes to the air dryer to a length that lets you install a hose end that would be connected to a bulkhead fitting that was installed in a bracket.  That gives you a solid termination point for that line, then make a new hose section that goes from the bulkhead fitting to the air compressor.  Now you have a permanent upgrade that gives you an easily serviceable section of hose to connect the air compressor to the hose to the air dryer.  Supporting the hose with a bulkhead fitting secured to a solid bracket is good practice.

I use this hose for brake lines in my race cars, although in a smaller size.  I run up to 1,000 psi in it, and I have never had a fitting failure, in fact the hose will usually fail in testing before the fitting attachments fail.  The teflon liner takes all of the pressure, and the stainless braid is just for protection.  It's a good system.

Brian
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« Reply #13 on: January 03, 2012, 04:53:14 AM »

Call Jefferson in OKC Ed will tell where to get hose made and give you a name of a shop,there are 5 shops in Tulsa that do bus and one in Wagoner all good shops and that hose is Teflon

good luck
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« Reply #14 on: January 03, 2012, 09:03:06 AM »

I know the hose in question and how it runs. If you decide not to splice: to define put mechanical ends on two hose ends after you cut out of short one or two inch damaged area: and use connector. Make sure your new run to the dryer has no sags(place to collect moisture) and is secured well.  Joe is in the repair business and charges $125 per hr I believe and knowing where the original clamps are and routing I would hate to estimate hrs $$$$$$$. If you feel uncomfortable about hose repair; do replace it.. I don't---- I repair hoses that run up to 2500 psi on a regular basis.  Would never repair a line I could get to both end of.    Just for your information. the power steering lines that go to the front are in two pieces. They have a splice at rear baggage bay wall  from differential area. I am replacing them while I have the floor out. There is a mechanical splice there that would be a bugger to get at,  The air hose in question runs above them.  I do not compromise safety and feel confident in repair of any line I would if not I would replace if in doubt. Talk to your local hose guy.   No more from me.   I agree to dis agree.   Bob

You are right on the labor. Called Prevost this morning and they said 4-6 hours labor to remove and replace plus the cost of the hose itself. Described the routing as you did clamps and all. It would be nearly $1000 to replace it there.

"Might be an opportunity to add a ping tank - make a new hose that is short, to a ping tank in the engine compartment, and cut the old hose at the leak point and attach the old hose to the ping tank with a new termination fitting."

They recommend replacement but told me customers often install a ping tank ore couplings themselve. He said some Prevosts come with them..

Now I need to find somebody in Southwest Oklahoma that can either install a coupling or a ping tank and do it right. Once that hose is cut I am dead in the water. I may be able to limp it to OKC or Tulsa but I sure do not want to press my luck if I don't have to.

Sorry for my ignorance luvrbus but is Jefferson a bus place?

Thanks guys,

DKO
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