Replacement A/C belt and tensioner??

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Replacement A/C belt and tensioner??

July 29, 2015, 01:08:48 pm

So I got a new belt for the A/C that shredded during my trip from Jackson, WY to Houston and the tensioner pulley seems to rotate with ease. I will install the new belt but it seems that the tensioner is held in place by one bolt. I presume that I will need to get a socket behind the tensioner and loosen the bolt to allow the new belt to fit into place. What is the best way to tighten/position that bolt/tensioner so the belt will be tight enough without overtightening it?

As usual your input is essential in completing this project.

Re: Replacement A/C belt and tensioner??

Reply #1 – July 29, 2015, 01:50:18 pm

Scott,
The tensioner arm and idler wheel simply rotate enough to allow belt to be put into place. Look for the cast-in square recessed hole in the arm, insert the appropriate 3/8" or 1/2" drive breaker bar, rotate and slip belt into place. If the belt doesn't slip into place, you have the wrong belt. If the idler arm isn't restrained to about the first 1/3 of its full travel, you may have the wrong belt. If the idler isn't dead quiet (doesn't bob) with the engine running and the belt has had a few minutes of break in time, the idler tension spring is becoming weak or the idler bearings may be going rough. Other than that, the idler assembly is essentially nonadjustable. A new "keeper" detent hole on the engine block can be drilled on some engines, to change the unloaded "home" position of the idler assembly, but not on all coaches and is best left to the experts..
Hope this helps.
Neal

Re: Replacement A/C belt and tensioner??

Reply #2 – July 29, 2015, 02:51:22 pm

Neal has it! Takes only seconds to replace the belt if no other belt in front of it. If it's a serpentine flat belt, put a $5 hardware store angle indicator (vertical angle) on the roller to make sure it agrees with the pulleys. Coach can be at any angle to do this. Gates fleet green stripe belts are a good choice here. With the right length belt, the tensioner is self adjusting. Keep a spare as most of the time when they come off, they are long gone when you need the length specs.

Pierce

Re: Replacement A/C belt and tensioner??

Reply #3 – July 29, 2015, 02:58:17 pm

Thanks Neil and Pierce for your prompt responses.

I will look at the tensioner arm again as it did not appear to be spring loaded. I got Gates Green Stripes as replacements. I also got a spare - didn't carry spare belts - do now.

Re: Replacement A/C belt and tensioner??

Reply #4 – July 29, 2015, 06:48:56 pm

New tensioners are easy to install and those in the know recommend new closed style Gates tensioners. (not the Dayco types that have an open slot where the spring end hangs out)

Re: Replacement A/C belt and tensioner??

Reply #5 – July 29, 2015, 09:01:40 pm

Is there a specific Gates PN that will install where the OEM one bolts on?

Re: Replacement A/C belt and tensioner??

Reply #6 – July 30, 2015, 12:01:32 am

Scott,

You can cross reference from your old tensioner numbers if you can find/read them. About $100 if I remember what others have paid.

You haven't said if a V belt or serpentine flat belt with your coach. With a serpentine belt, alignment is more critical as an out of alignment tensioner will cause one of the belt edges to fray as it pushes against a pulley edge and gradually the belt will be destroyed. A few months ago, I finally changed the 7 rib belt on our Toyota after 160,000 miles. No wear as it was in perfect alignment. Our U300's tensioner was out of alignment and ate belts like popcorn when we bought it. A symptom of poor alignment is the small jumping movements of the tensioner idler pulley at idle speed. I just aligned ours, oiled the idler bearing and it's worked fine for six years now with almost no movement at any speed.

V belts are less of a problem and tolerate mis-alignment better.

Pierce

Re: Replacement A/C belt and tensioner??

Reply #7 – July 30, 2015, 06:57:59 am

Scott,

You didn't say what engine you have. I went through this yesterday on my M-11. It uses an idler pulley not a tensioner. I couldn't break loose the bracket bolt without an impact gun. There is very little space or swing room. I used a 2X4 and pry bar to tension the belt before tightening the bracket bolt with the impact gun.

Re: Replacement A/C belt and tensioner??

Reply #8 – July 30, 2015, 08:05:00 am

Our U320 has a 450 Cummins and the belt is a V belt that goes around the AC compressor on the right side of the engine. Idler Pulley or belt tensioner?

Re: Replacement A/C belt and tensioner??

Reply #9 – July 30, 2015, 08:25:03 am

Scott,
I apologize. In my haste to be helpful, I didn't slow down and figure out which engine you have.
Brett is absolutely correct. You mentioned tensioner and I jumped to the wrong conclusion. I described how to install a belt on an 8.3 with Gates or Dayco belt tensioners and your engine (like my 2002 M11) most likely has the idler pulley with the difficult access bracket arm that Brett describes. On my AC compressor belt, I have had to clear fuel filter components interference and then use an impact driver to break that bolt free, just as Brett describes.
Sorry for creating this confusion.
Neal

Re: Replacement A/C belt and tensioner??

Reply #10 – July 30, 2015, 08:28:07 am

Quote from: Carol & Scott – July 30, 2015, 08:05:00 am

Idler Pulley or belt tensioner?

Scott,

Should be just a idler, your belt should go around 3 pulleys. They are compressor, idler, engine drive.

Pamela & Mike

Re: Replacement A/C belt and tensioner??

Reply #11 – July 30, 2015, 08:30:43 am

My 8.3 has a single belt that goes only to the A/C compressor; no idler pulleys.

Trent

Re: Replacement A/C belt and tensioner??

Reply #12 – July 30, 2015, 08:36:00 am

Quote from: TulsaTrent – July 30, 2015, 08:30:43 am

My 8.3 has a single belt that goes only to the A/C compressor; no idler pulleys.

Trent

As does mine

Re: Replacement A/C belt and tensioner??

Reply #13 – July 30, 2015, 08:46:21 am

Sooooo....Idler Pulley and a PITA to get to and adjust.

Re: Replacement A/C belt and tensioner??

Reply #14 – July 30, 2015, 09:32:16 am

Quote from: Carol & Scott – July 30, 2015, 08:46:21 am

Sooooo....Idler Pulley and a PITA to get to and adjust.

Correct, Scott.
Sometimes technology (and/or convenience) marches backwards, as in the case of the 8.3 and the M11 AC belt tension adjustments.
And, when I try to help out, I have to be careful as I find that more and more, "The faster I go, the 'behinder' I get."
Sorry,
Neal

Re: Replacement A/C belt and tensioner??

Reply #15 – July 30, 2015, 10:41:47 am

Anyone have the belt width/length or a part number to go along with the engine model for the forum records?

Pierce

Re: Replacement A/C belt and tensioner??

Reply #16 – July 30, 2015, 12:30:08 pm

Thanks guys -

I always appreciate input - nothing to be sorry about Neil.

When I get my mind set to tackle this PITA "little" job I will try to get a PN for the Idler Pulley and foreward to Barry and Michelle.

Thankfully it does not have to be done today or tomorrow as it's 96 deg. now and it's too hot to screw around with it.

Re: Replacement A/C belt and tensioner??

Reply #17 – July 31, 2015, 06:58:56 am

For the M-11 the belt is a Gates 6440. Your Owner's Manual lists your belts. My idler bearing was bad. I drove it out, took it to NAPA, who matched it to an alternator bearing. You shouldn't need to replace the pulley unless the pulley itself is damaged.

Re: Replacement A/C belt and tensioner??

Reply #18 – July 31, 2015, 10:37:20 am

Got 'er done. Bolt broke loose fairly easily used a baseball bat as a breaker bar and re-tightened. Started engine, turned on the dash AC and everything is fine.

Thanks again for your interest and input. As usual the perception of the problem is usually worse than reality.

Re: Replacement A/C belt and tensioner??

Reply #19 – July 31, 2015, 11:08:44 am

OK, that begs the question...How do you use a baseball bat for leverage?

Re: Replacement A/C belt and tensioner??

Reply #20 – July 31, 2015, 11:25:08 am

I guess it depends upon whether you are left or right handed............................Just kidding.

My baseball bat was the only long somewhat thin rigid item that I could lay my hands on to use as a lever to apply pressure to the pulley then maintain pressure so I could tighten the bolt.

I figured that I would get some smart a** comment about the bat.

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