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Belt Tensioner Issues
Can’t explain belt tensioner retains air pressure when filled from a air hose thru the schrader valve. Three weeks and tight belts with coach sitting.
I have a new regulator and a new check valve. Can’t believe 50 plus dollars for check valve at Prevost. That is another story.
When I drive the coach the belt tensioner loses tension within a few hours. The bladders go completely flat. I can then fill with air hose and belts tighten and stays tight till next time I drive bus.
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12 Replies
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On my bus: the air source for all the detroit engine belt tensioner bags is the accessory/auxiliary air system. There is a regulator and gauge in the engine compartment and I set the regulator output to the bags at 52 psi.What does your gauge say? before, during, and after? -
Is the check valve installed in the right direction?
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There is no gauge but checking with digital gauge I have 49 8 lbs.
The check valve is in correct direction as the accessory system goes to zero after about 6 hours and belts stay tight. It holds air for the last time it sat for three weeks and didn’t leak down. Took it out to exercise the unit and the belts were loose the next morning. Don;t know how long after trip they actually lost air.
Need to take out early in morning and check time for the belts to loose air.
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gmjdw,
Would it be possible to post picture of your $500 check valve ?
AL
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George, the way I read your first post I was under the impression while driving the belts lost tension. I understand what you are saying now.
That belt tensioning system has at best been annoying. If it wasn’t the check valve it was the control valve, or it was the pressure regulator, or the fittings, or the air bellows themselves.
I finally gave up chasing problems and leaks and using scrap pieces of threaded rod from brake chambers I made a jack screw system to replace the air tensioning system and my problems are gone.
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I may go the way of Jon and say the heck with it.
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Here is what my setup looks like. I replaced the original leaky regulator 6+yrs ago with a $35 unit from Tractor Supply. Hadn’t had a problem since.
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This check valve is fitted after the control valve in my marathon, it will hold air for months, if the the valve orientation is correct and the c/v is good, all synflex connections and air bags are leak free.the system has to hold air.
if all the above are in good condition and fitted correctly it cannot leak down.
The circuit cannot differentiate between where the air is supplied from !
Provost,s are smart machines , but not that smart
You have a leak
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Just a wag, could the control valve be in the wrong position. I can’t imagine but…
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I removed the control valve
check valve can’t be wrong as the belts have held tension for over three weeks and then when I took it out to exercise the coach the next day belts were loose.
This is a repeatable event over the last couple months.
Air up the belts thru the schrader valve and belts stay tight. We have had them stay tight for over 6 weeks. then take it out for a road exercise and the next day belts are loose.
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Looking at your pic,
I see your gate valve is closed, keeping air upstream when not in use. Your site glass is showing zero.
Arrow is pointing at what appears to be brass coupler ….it’s the check valve to keep air in your mini bags.
AL
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Eliminated the tensioner, mini air bag years ago. Never had an issue since. Just install stainless bolt in it`s place , adjust tension, tighten an drive.
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