View Full Version : Air Bag for cooling fan Belt tensioner

12-05-2013, 08:55 PM
I am trying to replace a leaking (bad) air bag on the belt tensioner for the cooling fan. The problem is, after removing the air line, the large nut on the bottom that holds the bag in place is rusted, and when I turn it, it turns the whole air bag. So, I tried everything to hold it, and the nut still will not break loose. I even cut the top of the bag off, to get to hopefully something to grab, but nothing in there. I even drilled a hole through the plastic base and the top of the metal stud, put a screwdriver through it, and then, tried to turn it with a long torque wrench/ratchet.​
12504So, before I get the Torch out, does anyone have a tip on getting the 15/16 nut off the bottom?​

12-05-2013, 10:39 PM
If you can get a grinder in the space with a cut off wheel it will do the trick, maby safer than a torch! Ask me how I know, good luck. Bill

12-05-2013, 11:08 PM
I'm assuming you've tried WD 40 or similar and let it sit overnight. The grinder sounds like the answer if not.

12-06-2013, 12:54 AM
Chesterton makes a product called SpraSolvo that makes WD look like water it really works well it needs time to penetrate but that is all I ever use other than heat or cold when possible,
I suppose when you try to cut it it will start spinning !!! That would be my luck, On a longer shaft I have used a fire extigusher to cool a shaft then a torch to heat a nut and whipped it right off, We used to have to put huge bearings on tapered shafts so we kept the bearings in hot oil in a deep fryer pulled them out with big gloves and slid them on the cylinder shafts in about 1 min you could not get that bearing off to save your life after it cooled,
Good luck,

12-06-2013, 06:33 AM
The problem I've had with soaking it, is getting it to go up, mostly drips off. The biggest impact I can get on it is a right angle 3/8 drive, which isn't strong enough. I do have an air chisel, I'll try that next.

Bill, did you get yours off with the grinder/cut off wheel?

12-06-2013, 06:41 AM
Would it be worth the extra work to take the bracket off so you could turn it upside down or to labor intensive. " Sometimes the long way is the short way. "

12-06-2013, 08:32 AM
If you have an impact wrench and you have room to use it - Have a helper grab the bag with a channel lock and give it a few wraps with the gun. Sometimes that has worked for me in similar situations.

Good luck!

PS - I like to use Kroil oil as my penetrating oil of choice and oxy/acetylene torch as last resort:)

Joe Camper
12-06-2013, 09:18 AM
Aren't those Canadian engineers wonderful. At the piont where u got to now there r a few choices none prefferable . Find a way to grab the post, cut the nut, remove the bracket.

12-06-2013, 10:38 AM
I've tried all of the above except for taking the bracket off, I would have to remove the whole fan assembly. After cutting the bag off, removing the top, and taking my side grinder and getting the plastic base off, I am now down to the bolt. My side grinder will not reach to the bolt.
I should be able to get it with a smaller cut off wheel than the one I have, or..........here comes the torch!

Joe Camper
12-06-2013, 10:47 AM
I find it beneficial to not dwell on any 1 method when I get to something like this. Try it and if it is not happening move on to another approach. Be carful those grinders r dangerous with cutting wheels on them and even worse in close quarters. Cant grab the nub with some Vice grips. I remember cracking away the base on 1 but don't recall what I did then. I know it was creative :rolleyes:

12-06-2013, 11:30 AM
Yea I agree Joe, I've got just about every tool in my shop by this project!

12-06-2013, 11:55 AM
Maybe try one of those "nut crackers". I have not needed to use one myself - but have looked at pictures. It's a ring that goes around the nut with a little chisel on one side that you screw in towards the nut - it supposedly will split the nut.

12-06-2013, 02:02 PM
Jerry, it's great you have the tools and know how. For some, probably most, they would be in way over their head at this point. BTW, I think $4K for a radiator is nuts. There are plenty of places that will recore your old unit and I'm sure for far less than $4K.

Best of luck.

12-06-2013, 04:35 PM
Gil, that was for a new one from Prevost Jax. Yea, I wouldn't take the engine out, but I like working on anything with nuts & Bolts. I'll post a pic with the new one installed hopefully tonight..............

Dick in Wisconsin
12-06-2013, 08:49 PM
Do you have a welder? I watched a friend weld a nut on a broken stud. When it cooled he was able to put a wrench on the nut and with a breaker bar and piece of pipe get it to finally loosen up. Build up the weld material from the inside of the nut. Told me had done this many times.

12-06-2013, 10:18 PM
Finally got it done, cutting torch took care of it!

12-06-2013, 10:25 PM
I have cut pretty big bolts with my little dremmel with cut off blades you just go through a few blades ?? and its pretty small,

12-06-2013, 10:46 PM
Jerry yes got it off with the grinder sorry for the delay. Looks like you methode worked like a charm and Kudos to the nice andonized fittings!

12-07-2013, 06:27 AM

Was the second clamp supplied by Goodyear or Prevost? It seems a little strange to put a clamp directly over another clamp.

Great job and thanks for the pictures.

12-07-2013, 08:25 AM
Gil, Yea, that's what I thought too. I even called Prevost back to make sure, after I saw the clamp. They said it keeps the original band from expanding over time. They were in a Prevost parts bag so I think they are a Prevost item, not Goodyear.
The clamp is adjustable and has a constant pressure spring on the screw to tighten it, just like the clamps on our radiator hoses and CAC hoses.
Around the top of the bag (behind the clamp) is where mine was leaking.

12-07-2013, 10:07 AM
Hmmm, mine were leaking behind the clamps too. The second clamp suggests that if your bag is leaking around the factory clamp you could replace the existing clamp with a new clamp and be good to go. Given these seem to last for about 100,000 miles, I guess it's generally not a big deal to replace them. Your replacement issues hopefully being an exception. I know some have considered replacing the bags with traditionally screw type tensioners so they don't have to worry about deflated bags when they start their coach and the general issue with leaks. Personally, I like the bags and hope I never need to use them for an unanticipated belt failure, but to each their own. My only unanticipated belt failure took out the 3 belts on the one Prevost pulley and the 2 belts on a pulley installed by CC. I have no idea which took out the other. The Prevost belts were replaced in less than a minute and the CC belts about 30 minutes.

12-07-2013, 07:42 PM
Yea, mine were original with 140k on them. Being the bellows have a plastic top and bottom, guess that's why the additional clamps are spring loaded.

I'm told the bags are on there because Passenger Bus drivers needed to be able to change belts quick.
I like the idea myself.

Joe Camper
12-07-2013, 09:27 PM
Its another piece of the mechanical sculpture. Its fun seeing the gleam in the eyes of someone who has never looked in the back doors before. We got STUFF

12-07-2013, 10:02 PM
10-4 on the STUFF

Dick in Wisconsin
12-07-2013, 10:34 PM
You can never have enough STUFF!

12-08-2013, 10:35 AM
I know the first time I looked in a Prevost engine bay I thought .......WOW cool stuff here!