Belt Tensioner Pulley, Bearing Replacement

[ajducote]

I discovered that I had a noisy bearing on 1 of my idler pulleys for the belt that runs the 270 AMP 12 volt alternator. It is a fairly easy job to fix.

1. Loosen the bolts that hold the plate with the pulleys to the backing plate on the engine. (that is the 2 bolts in the slots on the plate.)
2. Use the bolt at the top of the plate to loosen the tension on the belt and remove the belt.
3. The hard part seems to be getting the dust cover off of center of the pulley. I had to use a large dull chisel and come at it from the side and kinda tap / pry it out. I tried several other things and nothing else I tried worked. You may want to remove the dust cover before you loosen the belt. That way the pulley won't move on you while you work.
4. Once the dust cover is off remove the center bolt.
5. With just a little prying from the rear, the pulley came off.
6. Use snap ring pliers and remove the snap ring.
7. I used a large socket and drove the bearing out of the pulley with very little trouble.
8. New Bearing came from Prevost, Part Number 510618, cost $72.05. The bearing is a NACHI part number 30BGS1D53. I could not find that bearing on line or at the local NAPA store.
9. I used a large 1-15/16" socket to drive the bearing back into the pulley.
10. Re-install the snap ring.
11. The pulley went back on the stud on the engine with very little persuasion.
12. Install the bolt, dust cover, and belt.
13. Tighten the top bolt to get tension on the belt, then tighten the 2 bolts that hold the bearing support plate to the backing plate.
NOTE: I need to get a belt tension gauge, will look for 1 today.
14. Test your work.

[dale farley]

Good job Andre. Nothing tells the story like pictures.

[Jon Wehrenberg]

Periodically before a trip we should be checking our idler pulleys. Relax the tension on the belts and spin all the pulleys. Long before a pulley bearing approaches a failure it will make a slight noise, or feel a little roughness when spinning by hand.

I replaced the bearing in my OTR idler because by checking I found it to not rotate smoothly. These are easy fixes, but can mess up a trip if they happen when we are on the road.

[truk4u]

Caution on removing the second pulley, the bolt will probably be left hand threads, assuming the one Andre did was right hand! I had to do them on my Marathon and got the bearings from IBP for 36.00 each.

Good job Andre.;)

[sawdust_128]

Are these bearings pre-packed? Do you have to lube them?

[JIM CHALOUPKA]

Ed, the bearing is lubed and sealed for the life of the bearing.

No further maintenance necessary.


JIM

[Jon Wehrenberg]

Bearings are actually generic. If you need to replace one it is likley it can be brought to the local bearing house and if the numbers are readable you can get one as cheap as possible.

Tom's advice is on the money.

[flyu2there]

Spot on Jon and they will usually press it on for ya!

[rickdesilva]

Not a bad idea to carry extra bearings. The pulley bearing combo is about $300 from Prevost.

[truk4u]

The older style pulley's (Manual Adjustments) were not available when I was changing out my 97. That's why I had to get new bearings and press them in like Andre did. At the time, Prevost didn't have replacement pulleys and wanted me to upgrade to the auto tension to the tune of about 1800.00 bucks.

Unless something has changed, I don't think you'll find replacement pulleys.

[Jon Wehrenberg]

I'm not so sure the lack of a pulley from Prevost has to be a show stopper.

Keep in mind that any pully, flat or grooved is all that is needed, along with a bearing of the correct ID. (Inside Diameter) The pulley diameter can vary because a longer or shorter belt can be used along with adjustment to compensate.

[JIM CHALOUPKA]

It might be a good idea to check out all the bearings, they all started life at the same time.

JIM

[flyu2there]

Jim,

My guess is that those bearings will last a lifetime and then some! I spect that incorrect belt tension, probably too tight, causes bearing wear.............

I had one fail in a Cummins Motor that I got a bit cunning with while tightening the belt...spensive lesson, guy charged me from where he was based to my (then) coach and back............ Not good in the Nevada Desert!

[rickdesilva]

I have attempted to have a backup on the items that I think could fail. My coach (XL ll) is very basic. The alternator setup is a basic manual idler bearing/pulley alternator adjustment. I tried to duplicate the pulley/bearing setup non-oem but couldn't. So I bought a backup from Prevost. It was available but possibly it was available because of the year of production.