Belts: Learn it or Park It.

[aggies09]

I have been following Adam's questions and the responses relative to being able to change one's belts in the case of an emergency. I found this to be a critical line of thinking and sought to find any posted tips on changing the belts, especially after A-1's comment that if you didn't know how to do this.....you should park the bus until you learn. I found this to be relative and profound advice.

None of the posted articles that I could find detail a procedure or offer do's and don'ts for changing the belts on a Series 60 or 8V92. Would it be possible for some of the more expert mechanical members of our group to share a little wisdom on this subject? I am sure that it is old hat for most of you, but the last belt I changed was on my '67 Mustang with a straight six. It looks a lot different than my S60.

[Jon Wehrenberg]

Good idea, but since the answers vary based on how the coach was built or converted not all answers will be valid.

On my 8V92 and my Series 60, both with OTR there is a valve at the top center above the engine compartment doors. Turn the valve 90 degrees and the air cylinders (on the 8V92) or the air bellows will relax and the belts can be removed and replaced.

On the Series 60 I have an alternator driven by a serpentine belt. To remove or replace that belt I use a 3/4" drive socket wrench in the spring loaded belt tensioner to release the tension on the belt. Some Series 60 coaches of the same vintage as mine use a mechanical tensioner that has a jack screw type belt tensioner that just requires loosening or tightening with a wrench.

Having said the above I know that there are coaches that do not have OTR, that have two alternators, driver's air only, and those coaches will have other ways of loosening belts for removal and replacement.

[Loc]

On my non-bus air coach, the air valve actuator is at the top of the engine bay. A quick flip and the three belts that drive the miter box that turn the fan are easily changed. We have the same serpentine driven alternator as Jon so a 3/4 drive ratchet does the trick. I haven't studied the belts that drive the driver's ac, but they come of the miter box.

[Jon Wehrenberg]

A word of caution here.

On XL chassis without OTR I believe all belts on 8V92 coaches are loosened and replaced by loosening one of the accessories such as an alternator or AC compressor. They require tools in all cases.

I do not know if that is true on Series 60 coaches or XLII coaches.

There are many configurations out there such as XL, XLII, H3, coaches with the 8V92, with the Series 60, with and without OTR and then all of them have variations depending on how the converter chose to set up the engine driven accessories such as with converter installed AC compressors or second alternators or even belt driven generators.

So you not only need to carry spare belts, you should at least review what is going to be required in the way of tools or procedure to replace those belts.

[Jon Wehrenberg]

Here are two photos relating to belt loosening and replacement on my coach.

The valve is at the top of the engine compartment above the rear doors.

The spring loaded tensioner that is used on my alternator serpentine belt requires a 3/4 socket wrench to push on it and relieve the tension. When I am on the road I use a 3/4 inch square piece of tubing and a box wrench. It takes a little more force to release the tensioner, but it saves me from having to carry the 3/4 inch socket wrench.

[aggies09]

Thanks guys. I plan on acquiring extra belts and making sure that I have what I need to make any belt repairs before our trip this weekend to the Kerrville micro rally. Thanks for the input.

[adamdegraff]

Here are two photos relating to belt loosening and replacement on my coach.

The valve is at the top of the engine compartment above the rear doors.

The spring loaded tensioner that is used on my alternator serpentine belt requires a 3/4 socket wrench to push on it and relieve the tension. When I am on the road I use a 3/4 inch square piece of tubing and a box wrench. It takes a little more force to release the tensioner, but it saves me from having to carry the 3/4 inch socket wrench.

FYI, my alternator serpentine belt does NOT have a spring tensioner. Instead, it has a long bolt that moves a roller up or down, increasing or decreasing pressure/tension on the belt. There are 2 or 3 bolts that set the roller in place once it is where I want it. I have now replaced every belt in the the engine with the exception of the aux a/c compressor (Marathon add on) and the alternator belt. Neither looks difficult. I have worked on heavy equipment before (tractors, backhoes, dozers, etc.) and I have to say that the belt replacement on the DD series 60 was SO EASY I could hardly believe it. Deflate air tensioners (twist red lever shown in the above post) slip the belts off, slip new belts on. Couldn't be easier. For my driver's air compressor (opposite radiator fan pulley, but on the same gear box) I couldn't get it loose. So I just rolled the v belt off with a wrench there to derail it. Rolled the new one back on (by hand mind you) and it snapped right on. No problems.

I can't tell you how glad I was to have the correct belts on board. I also had gloves, tools, etc all nice and handy. Thanks to the folks at POG for suggesting this. You saved me a LOT of money and a LOT of time. You guys (and galls) are all great!

Best,

Adam

[Jon Wehrenberg]

Adam,

FWIW, your is the jack screw type tensioner I mentioned previously. I don't remember who it was, but someone had a problem with the idler bearing on one of the pulleys on that belt tensioner and if I recall that is no longer supported. The fix should your bearing fail on an idler is the replacement with the spring loaded tensioner shown. That was fairly pricey as I recall.

Because of the post mentioning the failed bearing I checked all of my idler pulleys and found one to have a bearing that was failing. Fortunately I was able to get a replacement bearing and replaced the bad one. The bearing was a press fit, but with a big hammer and some conversation I convinced it to come apart. For an extended trip like yours take the time to loosen or pull your belts and roll the idlers to make sure the bearings are smooth and have no play. Replacing a belt is not a big deal, but a failed idler and no replacement parts is a show stopper.

[adamdegraff]

Jon,
much appreciated! I will do so.
Adam

[adamdegraff]

Adam,

FWIW, your is the jack screw type tensioner I mentioned previously. I don't remember who it was, but someone had a problem with the idler bearing on one of the pulleys on that belt tensioner and if I recall that is no longer supported. The fix should your bearing fail on an idler is the replacement with the spring loaded tensioner shown. That was fairly pricey as I recall.

Because of the post mentioning the failed bearing I checked all of my idler pulleys and found one to have a bearing that was failing. Fortunately I was able to get a replacement bearing and replaced the bad one. The bearing was a press fit, but with a big hammer and some conversation I convinced it to come apart. For an extended trip like yours take the time to loosen or pull your belts and roll the idlers to make sure the bearings are smooth and have no play. Replacing a belt is not a big deal, but a failed idler and no replacement parts is a show stopper.

Hi Jon and all who are reading this exchange. I wanted to post a picture here along with this. There are 4 pulleys associated with the alternator serpentine belt. Jon, would you mind telling me which one or ones I should check? There are two idlers, right? And two pulleys. One from the engine itself, one for the alternator. Everything else is just free wheeling? If I were to need to replace this tensioner, would the whole black contraption have to go? Would I have to plug the holes? :-) How much would the fix be... I shutter to ask.

Thanks,

Adam

[Jon Wehrenberg]

Adam, maybe someone else can chime in with an estimate for the switch from your pulley tensioner to the spring loaded one. Personally, I would not upgrade unless I had a failure that required it.

The pulley to the far left is the driven pulley. The two center ones are idler pulleys. Check those bearings. The one above and to the right of the power steering pump is an idler pulley that should also be checked.

I believe all of these have pressed in bearings. If I am not mistaken the bearings are removable and readily available at local industrial supply houses like WW Grainger if you are ever in the need.

[truk4u]

I rebuilt the idlers on my 97 Marathon and got the bearings from IBC. You have to press the old ones out and new ones in, but an easy job. Be very careful, one of the idlers is left hand threads. Don't call Detroit or Prevost, they want to sell you an 1800.00 conversion kit. I think the bearings were less than 100 bucks.

Adam - the belt tension needs to be done using a gauge, the King has my gauge and will be available at Spearfish.

[adamdegraff]

I rebuilt the idlers on my 97 Marathon and got the bearings from IBC. You have to press the old ones out and new ones in, but an easy job. Be very careful, one of the idlers is left hand threads. Don't call Detroit or Prevost, they want to sell you an 1800.00 conversion kit. I think the bearings were less than 100 bucks.

Adam - the belt tension needs to be done using a gauge, the King has my gauge and will be available at Spearfish.

I do want to test my bearings before I take off. How will I be able to tell if they are good? Should they just spin nice and clean? No rattling, smooth, solid? Will I just KNOW if they aren't good?

As for the tension gage, can I just mark the spot by etching a line on the part that moves and the part that doesn't? Assuming I don't change belts, wouldn't it be the same setting? Or might it change and need to be reset? What if I did change belts. Could I just eyeball it? Obviously this is a case in which the spring tensioner would make things easier. I guess I'm not actually all that worried about any of this, as things seem to be going well, but after my last incident when the driver's a/c locked up, I sure am glad that I had asked so many questions.

So, what's this tension gage look like? Mmmmm, new tool.

Adam

[jimshoen]

Does anyone have a recommendation on where to buy a belt tension gauge for the surpentine belt (200 lbs)?

[Jon Wehrenberg]

Adam,

When you roll your idler pulleys you will know. They will be smooth, tight, and will rotate freely. A bad bearing will have spots where it drags, or it will not roll freely, it will be loose or it will make a noise.

As to marking the adjustment point, belts stretch so what is a good setting for your belts now may not work for a new belt. I haven't used a belt tension gauge, but that does not mean it isn't a good idea to have one. But if you do not have one just try to put enough tension on them so they are not slapping when they are in motion, and not so tight they are like a violin string. Maybe Joe C or someone else can give a better description.

[Ray Davis]

Does anyone have a recommendation on where to buy a belt tension gauge for the surpentine belt (200 lbs)?


Jim C posted a link to the gauge recently in another thread.

http://www.midwayautosupply.com/pc-48966-261-gates-krikit-ii-v-belt-tension-gauge-91132.aspx