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belt tension regulator — leak?
Don’t know if I have a problem or not with this regulator. Belt tensioners seem to operate fine with engine running, so, no issue there. However, I notice a little air escaping from the open fitting on the bottom when the engine is running and for maybe 5-10 minutes after I shut down. It’s only a slight pressure. I can almost stop it by putting my thumb over it. Putting the handle 90 degrees in the other position is definitely the belt service position to let all the pressure off as the belts immediately go limp. Is it normal for air to escape from this regulator? This leaking does not occur if I inflate from the aux compressor, only when I run the engine and primary tank inflates. My coach is a 1986 XL built by Hickox.
I really enjoy the wealth of information available on this forum.
Paul
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8 Replies
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Others with more knowledge can answer but it is not supposed to leak at all, from my view The danger is if there is a leak, even when the engine is runnng, the leak can become pronounced and affect the ability of the two valves to remain fully extended. If that happens, the belt on the radiator drive (and dash air conditioning compressor) can become less engaged (less efficient) and the engine cooling will definitely be affected and the temperature will rise to a shutdown mode if allowed to continue. My experience when this happened to me was that the engine hit 220 and I freaked out. When you get out to check it with the engine running, it will appear to be operating correctly and the temperature will go down….the problem, comes when you get under operating conditions (higher RPMs) and other conditions running brings…
The fix is easy. Take it apart and redo with a sealing tape…
Pres.
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Not supposed to leak.
Had the exact same problem, small leak on the bottom elbow coming out of the 4 way valve.
At some point in time ( 4-5 years ago), Prevost had a rebuild kit for the 4 way valve consisting of a upper and lower seal for the precision 4 way ball valve….not anymore, you have to buy the whole valve ( $279)
I also found that the old regulator ( to the left of the valve) had a leak all the way around the diaphragm, tried tightening the bolts and would not do it- bought a new Regulator ( $ 45) as well as a new check valve on the feed (top) line into the 4 way valve ( $27).
When you change the regulator (if you have to), flip the mounting bracket and adjust it to the correct pressure. They come from Prevost unadjusted at 80 -90 PSi and you need 50-55 psi for the small bellows.
If you follow the piping, the air comes into the top of the 4 way valve through the check valve, exiting the left of the 4 way valve into the regulator, then into a T with the Schrader valve in the bttom and then you have the exit line that feeds the bellows.
What I did was to turn the bolt on the bottom of the regulator clockwise (loosen the lock nut first) and take it to an approximate position like you see on the old regulator. Then with the engine running and all things tightened and no other leaks (sopy water bottle here…), I used a tire pressure gauge to check the exit pressure from the regulator on the Schrader valve. Adjusted the bold in or out to get 50 psi and that was it. Tightened the lock nut and job done.
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I had the same leak out of the exhaust position of the 4 way valve. I put a 1/4inch pipe plug into it. Fixed. Now if I have to release belt tension, I just have to remove the pipe plug before I turn the valve.
Gerald
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Gerald, that plug is a hillbilly work-around I can appreciate, but how long has it worked for you? Any side effects?
Paul
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All answers are correct, including the pot shot about the hillbilly fix which I did on my last coach as a temporary fix. The regulator itself is also a candidate for leaks, and sometimes tightening the screws around the periphery cures it for a while.
The final cure is to get new ones, plus make sure if you don’t have one or have an old one, replace the check valve. Some coaches did not have them but add one on the inlet side of the regulator. If you put it on the outlet side of the valve it will work fine up until you need to drain air to change a belt. That’s the real hillbilly repair.
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Paul,
FYI, the primary tank is a brake tank like the secondary and there is no aux air components running off those tanks or the wet tank. The only air to the accessories is via the aux air tank, engine compressor or aux compressor supplied.
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Thanks to everyone for all the info. I went with the cheap fix for now: $2 at Home Depot for the plug.
Paul
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We took the air tensioner off of my bus. It started losing pressure on a trip and ended up ruining my belt, and my spare within a few hundred miles. We put a manual adjustment on the belt and took that potential problem out of them mix.
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