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movingon06

Air System Leak on Freightliner Chassis

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We have a 2007 Tiffin Phaeton with a Freightliner chassis that is losing almost all of the air in the air system in roughly a 24 hour period.  We have had a Freightliner repair service in GA and a RV dealer in FL work on it.  Freightliner in GA found a small leak at a fill valve, and they changed it.  There was still a leak.  We took it back to them.  They couldn’t find anything else.  The dealer in FL found some more valve leaks and a leak on an airbag.  They changed a rear airbag, tightened the valves, and repaired small fitting leaks.  We are still having the same problem. 

The air system does fill back up when the coach is running, and stays filled as long as the coach is running. 

Any suggestions?

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movingon06,

Welcome to the FMCA Forum.

I don't have any "secret formula" for finding air leaks on coach systems.  I just use a spray bottle with water/kiddie bubbles and a toothbrush (never my own) to apply to all joints and valves.  See which one blows bubbles.  Takes time, but not rocket science. 

You can start narrowing it down by whether both gauges go down at the same rate or if their rate of drop is different.  Freightliner, Gaffney can provide you with a chart of your air system.

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I"m a year newer than you on a Freightliner chassis. There was a problem around that time with the line/connector on the air gauge under the dash.  Brett actually found it when visiting my coach in storage.  FL replaced the gauge and never had a problem since. Not saying that is your specific problem but it is an area to no overlook.

 

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I'm not advocating smoking, but I have a friend who does, and he will take a puff, then exhale at each air junction, if an air leak, it will actually move the smoke backward toward him. Then of course as Brett said, the bubble test to affirm the leak. Again do not start smoking to do this, but most of us do know someone who does.

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Wayne has a good point.  I had the same problem with my gauge on a 07' Winnebago Tour...the fitting is plastic, cheap! 

Carl C.

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movingon06, I chased air leaks on our coach several times. Check to see if you have a connection in the front of the coach below or around the generator for a tow truck to connect to, mine was exhausting air from that and I have an air port in my drivers side compartment where my fuel tank and propane tank are for connecting an air hose, that was leaking also. Beyond all of my air tank drain valves leaking that was all I was able to find.

I found soapy water and a spray bottle to be very effective in chasing air leaks.

If you decide to crawl under the coach just be sure to place safety stands under it before crawling under to look for leaks.

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I had the same indication and took it to the Freightliner repair shop in Wilmington NC. They found the fittings to the air gauge fitting on the dash board cracked. Replacement of the gauge corrected the problem.

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I have a 2008 Winnebago Destination on a Freightliner Chassis. I had a similar air leak issue, which was a cracked plastic fitting on the dash gauge cluster. Replaced the gauge cluster, and problem solved! Gauge cluster is easily replaced (one multipin electrical connector and two quick connect air line connectors), but did require removing dash cover.

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Why spend money to fix an item that is working. Air bags fill up & keep up pressure as long as the motor is running. To level the coach I have to dump the air for the hydraulic levelers to operate.

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1 hour ago, Jeanbev said:

Why spend money to fix an item that is working. Air bags fill up & keep up pressure as long as the motor is running. To level the coach I have to dump the air for the hydraulic levelers to operate.

While I agree that size leak is not dangerous, were it mine, I would want to find and fix it.

Guess different standards of what is acceptable.

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10 hours ago, Jeanbev said:

Why spend money to fix an item that is working. Air bags fill up & keep up pressure as long as the motor is running. To level the coach I have to dump the air for the hydraulic levelers to operate.

 

On 7/2/2016 at 7:07 PM, WILDEBILL308 said:

Good question Brett. 

If I am towing on a long day I just start and run the car while we are eating lunch. I have never had a battery problem. Well OK, I one time I got to my destination and left the car hooked up till late the next day and forgot to turn it off and it drained the battery.

Bill

I would think that an air leak will cause the compressor to continuously run. That could possibly cause another problem of the air compressor failing. Finding and fixing the leak is the most logical solution.

Do not be afraid of the brakes locking up if you completely loose pressure. The coach will come to a gradual stop, not an abrupt screeching stop.  That is a problem in itself as it may not stop in time to avoid hitting another vehicle in front of the coach.  The foot brake has far more stopping power but without air it is not going to function properly.

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I know how air brakes work, thanks for reminding me. But for every leak, that means it will take that much longer for air pressure to build, mine will not release before it reaches 90 psi, and the buzzer  wont stop buzzing before 110. All that means that much time before I can start to move, and I really don't like annoying the neighbors any longer than necessary. Also with the new hearing aids the continual hissing sound is especially annoying. For every action there is a reaction, likewise for every inaction there is a reaction, for these reasons, that calls for action.

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Mine is 65psi for brake release and 75 before the high pitched buzzer goes off !  One time had to drive to a shop, 112 miles, in Colorado at 70psi...never again!  A couple off hundred bucks and some time now, can prevent thousands and perhaps losing your or someone else's life later !  Fix it...:wacko:

 

Carl 

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I have a 2001 Tiffin Allegro Bus on a Freightliner chassis and I have had this same problem.  After much ado I found: 

1 - The front airbags had pin hole leaks.  My mechanic found them while he had it on the lift doing an inspection.  He showed me the cracks.  After he replaced the airbags, air connectors and front shocks the problem went away.

2 - The problem came back.  They found and replaced the rear ride hight adjuster valve and the problem went away.

3 - I drove from Atlanta to Anchorage Alaska and the problem came back.  It seems the same valve they replaced in Atlanta had gone bad. Hmm...

If your leak down is like mine and deflates the bags in about 1 minute all you need are ears to find the leak.  Drive to a quiet place, turn off the engine and listen.  The air makes a clear hissing sound.   

So far mine is staying fixed.

The reason I wanted to fix it are two fold.  First, I hate to drive with the air down.  While my tank pressure comes up so I can drive in about 30 seconds ride height is not proper for another 1-2 minutes.  If I try to drive with the bags down it rides like a two horse wagon.  Second, until the air comes up completely my mud flaps drag and make weird noises.  

Without the leak, I can stop, turn off the engine, go have lunch or talk to the police officer then crank the engine and drive off with the ride height at the proper place.  With the leak I have to wait 1-2 minutes after starting before I get a reasonable ride.

Thanks for the tip about the gauge problem.  I'll look there if it happens again.

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Call me crazy but the slightest air leak will make me sick and I will worry about it constantly. I recently observed mine taking longer to build air. I noticed it at a CG, I actually had to rev the engine to build air. My air line was leaking between the compressor and dryer. $65.00 and 45 minutes later I replaced it. Funny it builds air so fast now it must have been leaking for a while, this coach never would air up so fast. it was so close to the engine I couldn't hear the leak without crawling under it while it was building air.

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After determining I had no leaks on the plumbing and bags, still had loss of pressure I checked the input valves on each tank.  I pressure tested them by putting 125 lbs of pressure to them and submerging in water.  I found leakage.  I tried to fix them by lapping the disc and it reduce the leakage but not eliminated it.  I finally replaced with new and I still have air pressure the next morning.

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I'm not sure this is the same topic but our 1999 class A Tradewinds coach (new to us) "lists" to the right meaning the air in that side is lower than on the left.  What could this mean and what is to be done about it?

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14 minutes ago, bdensford said:

I'm not sure this is the same topic but our 1999 class A Tradewinds coach (new to us) "lists" to the right meaning the air in that side is lower than on the left.  What could this mean and what is to be done about it?

RIDE HEIGHT needs to be adjusted.  There are two ride height valves in back (that is your side to side adjustment) and one in front. Simple job. Freightliner can give you the specs/measurements.

 

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On 7/6/2016 at 9:15 PM, jleamont said:

Call me crazy but the slightest air leak will make me sick and I will worry about it constantly. I recently observed mine taking longer to build air. I noticed it at a CG, I actually had to rev the engine to build air. My air line was leaking between the compressor and dryer. $65.00 and 45 minutes later I replaced it. Funny it builds air so fast now it must have been leaking for a while, this coach never would air up so fast. it was so close to the engine I couldn't hear the leak without crawling under it while it was building air.

This must be the season for air leaks. I just had to replace the same main air hose but I was alongside the road on 30 just east of Plymouth Indiana. 

Bill

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