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Air leak when in gear only
my Dad has a 1995 xl country coach. series 60 engine .. he has a bad air leak only when it’s in gear and driving .. the main Air pressure gauge cycles up and down ever few minutes. he has stopped for the nite. he has checked for leaks with brakes off and on and cant seem to find any leaks.. but the compressor/air pressure gauge cycles more frequently then normal. any ideas ? thanks Dave
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9 Replies
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another piece of info is when running at speed when the compressor kicks in it runs about 30 seconds
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Transmission control on these coach are they all electronic oor are they electronically controlled air operated? …
like the old stone Bennett shifters?
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Perform a DOT brake check. I would be very inclined to guess you have a leaking parking brake diaphragm. Report back here the results.
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well you guessed it .. he has a appointment at 12pst … at loves truck stop in lodi California..
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This is a good opportunity to remind readers of this thread that we have very reliable brake systems, but it is important to verify it is working as intended by doing pre-trip DOT brake test procedures.
A failed or failing brake diaphragm can go from a small seemingly inconsequential air leak to a large tear that will prevent travel. The same problem is just as likely on the service brakes as on parking brakes with different characteristics.
When the leak is on the parking brake system the repair that will keep you going is to plug the air to the chamber and cage the brake. All you will lose is one wheel’s parking brake.
On the service brake side of things you will see a fast loss of air when the service brakes are applied. The fix to that issue is easier because all that is needed is to plug the air to the brake. In both instances plugging the leak can be as simple as putting a dime in the fitting to block the flow. Not leak proof, but definitely will slow the loss of air. Another possible temporary fix is to use a vice grip to clamp the hose shut or bend the hose and wire tie it.
I am not suggesting you hold off replacing brake chambers until they fail, but if you experience a problem the temporary repairs keep you going until you can get service to replace the chambers.
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Jon: How long typically do you expect these parts and pieces to last? When do you replace?
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Prior to the Knorr-Bremse chambers I changed them every five years. I am changing them every ten years now primarily because the parking brake chamber has a different design and it appears to eliminate the diaphragm and use a piston with O rings.
I was at 7 years on my first coach when the parking brake diaphragm failed on a 30-36 brake chamber and I had to cage it on the side of the highway during an ice storm. That was when I established my 5 year schedule.
Prevost used to say in their service manuals and may still say to change brake chambers every year or at 100,000 miles, which ever came first.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
As a refresher, what size cap screws on end of brake air line
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I cannot remember offhand, but if you turn the wheels to the extreme I think whatever size is on the steer axle brake chamber is what all others will be.
I think I am right, but if not my memory is shot due to the stress of not getting dues money.
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