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Tighten Your Belts
If your tired of seeing loose belts in your engine compartment, there’s a solution. Even if you lose your aux air, your belt bellows should remain tight. Behind the valve that controls the air release and shrader valve for checking belt pressure is a small check valve. These tend to go bad often and both my 02 and BA’s 07 where gone. As long as you have a tight shut off valve, lines and bellows, you air will stay up forever and your belts will be tight.
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8 Replies
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Thanks Tom…is there a part number for this valve or could vary from coach to coach?
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Recently replaced mine and the new one went bad. So I put in two check-valves (yes, overkill, but cheap solution) and I’ve kept air in the belts without starting the coach for two weeks with no air loss.
Good tip Tom!
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In 2014 the part# was 530175 @ $45 from Prevost
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In Toms post the 1st picture is the valve we removed from the air assembly before the 45 psi regulator. This valve is his original mfg by Swagelok.
A good working valve but NOT for long term service. Valve components are made of low grade service material.
The invoice is from our purchase of the new valves listing the components and cracking pressure. I spoke with the engineering dept and explained the service conditions present. These valves are made of best materials money can buy. Heat rating is 400 deg. High grade stainless steel spring. Valve seal material is “vitron” a grade better then material in the Swagelok valve used.
Generator mounted Marathon AUX air pump with new check valve.
#1 order……Generator check valve also changed 1/4 inch male national pipe thread ( MNPT) cost $150 ea
#2 order ……Engine belts and mini air bags valve 1/8 inch male national pipe thread (MNPT) cost $130 ea
Valve Check Inc. 651-330-3437
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Al,
Thanks for all the great and detailed information as usual.
Do all Marathon coaches have these same valve configurations?
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Owners have installed a lot of check valves themselves. I hope everyone understands Al’s check valve location for the aux compressor subjects it to a lot of heat from the compressed air. Al knows that and it is a high temp valve for that reason. If the valve is located downstream from that point where the compressed air is cooler the check valves that are OK for cooler temps will work fine. The same principle applies to water traps downstream from the aux compressor. They also have to be located where the air entering them can be cool.
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Lonestar, thanks for the Prevost part number,.
Al, like always, great details with pictures, makes it easy / quicker to identify, purchase and replace – THANKS
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After changing my belt tensioners because 2 of the 3 were leaking, I noticed the air pressure was still dropping the tensioner system as fast as my aux system leaked down. So I removed the engine belt air tensioner check valve, Prevost pt# 530175, that was $45 in 2014 is now $57. Its back near the regulator and red handle dump valve. I replaced it with a $13 one from amazon.
I decided to see if I could fix the original. I took it apart. There are 3 pieces inside. A spring, piston, o-ring. I replace the o-ring with a # 008 from my harbor freight o-ring kit. I cleaned the rest of the unit with mineral spirits and re-assembled it. It appears to be working again. Now I have a spare 🙂
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