How do I adjust belt air tensioner tension

Scott & Heather · November 05, 2014, 10:01:24 AM

I am working to get the belt tightened just a little and have greased all fittings as well as made sure the piston and hinges all moved. Doesn't appear to be an air leak but I have no easy way of checking the pressure since the valve isn't a schrader valve. Do I turn the nut on the regulator and which way do I turn it to increase the air pressure?

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Seangie · November 05, 2014, 02:24:31 PM

Scott -

I think...if I remember correctly you turn it counterclockwise to decrease and clockwise to increase. Best way to check is air up the bus and right before it kicks out turn off the bus. Then turn the screw counterclockwise until the air kicks out and that will be a decrease in air. Put a mark on the screw with a Sharpie so you can see how much you turned it.

-Sean

Wandering the country in a 1984 Eagle 10S.
www.herdofturtles.org

bevans6 · November 05, 2014, 02:51:26 PM

Ditto on the clockwise to increase. I carry a tire pressure gauge with 1/4" pipe thread fittings on the hose, I took it apart and screwed it in to where the odd test valve is, and set mine to around 28 psi in a truck stop one afternoon.

Brian

Boomer · November 05, 2014, 09:27:40 PM

Why not go to the hardware store and buy a simple turn buckle and replace the air tensioner. Let's face it motorhomers don't put on enough miles to regularly have to change belts which is what the air tensioner is for, quick belt replacement. No air tensioner =
no leaky cylinders and regulators as well as no thrown belts when the rpm comes up before the tensioner kicks in. Same applies to the a/c belt tensioner if one has coach a/c. JMO

Scott & Heather · November 06, 2014, 02:37:42 AM

Sean and Brian thank you! Smart bus people make me happy. Boomer, tell me more....I googled turnbuckle and can kinda visualize the concept but in actual practice don't understand how you installed it. Did you just remove the air cylinder and mount it in that location? I hate the air cylinder system personally for a few reasons so I'd totally be game for a turn buckle system. Can you post pics of your install?

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wg4t50 · November 06, 2014, 02:40:15 AM

Boomer has a great point, but on my MC7, each belt air cylinder has a specific air pressure setting for the regulator adjustment, just need a air gauge, very simple.
Dave M

Scott & Heather · November 06, 2014, 02:41:53 AM

Dave you're up early...or late...

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Debo · November 06, 2014, 06:04:05 AM

I know the test/fill port on my MC9 for my air cylinders is a big Schrader-valve-flared-fitting looking thing - almost like an HVAC port. Does anyone have a good handle on the sizes, or have you made some sort of adapter? Sounds like a couple of you might have.

I was thinking it would be nice to have an adapter to go from that port to a regular car tire Schrader valve so you could just use a tire gauge on it. Something like this: http://www.toolsource.com/r410a-adapter-p-104284.html

I may be off on the sizes since I'm not sure what they are...

Boomer · November 06, 2014, 08:39:18 AM

I don't have a pic Scott, have not owned MCI's for years. Yes, the turnbuckle just replaces the air cylinder and you cap the air supply. Might take a few minutes more to change a belt but a small price to pay. Good hardware supply or somewhere like McMaster Karr.

lvmci · November 06, 2014, 09:39:28 AM

Hi Scott, like Boomer, I like simpler best, but In the desert south west I think there is a place for tension belt adjusters, from winter to summer, there is around a 100 degree temp change, and our buses are used in the dead of winter and dead of summer too! Lvmci...

Scott & Heather · November 06, 2014, 04:33:57 PM

Well, I think I can make a turn buckle work. But I also know I should check the tension often just to be sure I'm keeping up with the temp changes and belt stretching/contracting. An open end wrench to twist it should do the trick. Probably will need a nut to keep it from twisting on its own.

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luvrbus · November 06, 2014, 06:38:31 PM

Good belts don't stretch or contract,the older Eagles have long belts with just a manual adjustment idler and you never need to adjust those for years fwiw

Scott & Heather · November 06, 2014, 07:43:53 PM

Well, that bodes well for me converting it to a turnbuckle system

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Boomer · November 06, 2014, 08:17:03 PM

We operated our buses in temps from 0F to 120F on an annual basis with no ill effects from running manual tensioners. Those belts are tough anyway. We very rarely had to replace a belt and I can't remember ever having one break, just inspect regularly for cracking in the groove. Lots bigger problems to worry about IMO.

Scott & Heather · November 07, 2014, 03:54:34 PM

Done. Turnbuckle installed. Installed a nut and lock washer too just to be sure the turnbuckle won't turn accidentally and loosen the belt. This was easy and I'm actually really relieved to get that air cylinder out of there. It just wasn't tightening the belt anymore and I do think this was a part of my overheating issue. Belt is nice and taught now

thanks so much for the advice

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