air tension valve on mci 9

[platinum mci]

I'm not sure what you call it but the valve on the back of the engine compartment that keeps the tension tight on the belt for the blower wheels leaks air not to bad but I want to fix it, has anybody made these repairs and knows whats involved and what parts I would need.

[buswarrior]

I don't know about the 1/4 turn valve, but I bought new regulators from MCI  couple of years ago for $44 each.

My 1/4 turn valve for the alternator belt tensioner, which drives the piston both ways, needs replacement.

happy coaching!
buswarrior

[platinum mci]

Yes it is the 1/4 turn valve that is leaking, it leaks air out of the top.

[Paul]

To maintain the correct tension on the blower belt, the air cylinder must be properly adjusted. With the air system under normal working pressure and the pressure regulating valve set at 21 psi, the shaft length must be must be  11/4" + or - 1/8".  The 11/4" is the amount of rod out the cylinder to the jam nut at the rod end.

With a tire gauge test for the 21 psi, at test valve to the right of regulator, looking forward at the back of the bus.

We had worn pulleys on our unit and some one installed the regulator backwards. This let the full air pressure to the cylinder. Two new pulleys and a belt, cleaning and turning the regulator around fixed this. Only after servicing and replacing the regulator two or three times to find it installed backwards.

All working well now.
Paul   


   www.incredibus.com

[busnut104]

I took our local bus company advise, I took the air cylinder off and used a turn buckle. Bus Co. does all there's this way.

[platinum mci]

thank you paul for the advice, but what about rebuilding the 1/4 turn valve has anyone done this before or do you just buy a new one when they start to leak. I will check tommorrow to see if it is getting to much air pressure.

[buswarrior]

or, you could use a solid adjustable rod.

On both the blower belt and the alternator belts.

And re-adjust your low air warning/alternator inhibit to a lower pressure so you can get on with it sooner too.

happy coaching!
buswarrior

[buswarrior]

Nobody rebuilds that small stuff anymore. The rebuild kit versus a new valve are too close in price, and you don't know what condition the valve internals are in. Seats could be corroded, then the new seals are worthless.

Lots more for a busnut to do than spend time rebuilding small parts?

happy coaching!
buswarrior

[platinum mci]

ok thanks for the advice I will call mci tommorrow for a price on a new valve

[Paul]

I checked on line price of the valve from MCI.
4F-22-10              $141.14
4F-22-10RM          $119.81 (replacement)

This valve controls air to the regulator for belt tension cylinder or dump the air to it.

First remove old valve, disassemble, clean, replace O-rings and lube.
4F-22-18           O-ring stem seal body
4F-22-19           O-ring stem seal port
Try to find these O-rings locally.


If this does not work, replace with a ¼" ball valve. Then crack open the line from the new ball valve to regulator to dump the air.

Paul

[Paul]

Alternatively, install a second valve between new valve and regulator to dump air.

Paul