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bpu699 09-15-2020 11:21 AM

Idler pulley, anyone just change the bearings?
I see a lot of the aftermarket idler and tensioner pulleys are plastic, the stock one is metal.

Anyone know the bearing size required? Would like to order the bearings and belts before disassembly... Have a press and lathe if needed to change...

Any idea where to find this info?

Also trying to locate the required serpentine and water belts parts numbers needed for a 2000 Winnebago Ultimate Advantage, googling has been less than helpful...

kenwyatt 09-15-2020 12:12 PM

See you posted on the Cat forum, little more information on what”Cat” you have would probably help

bpu699 09-15-2020 02:35 PM


Originally Posted by kenwyatt (Post 5441651)
See you posted on the Cat forum, little more information on what”Cat” you have would probably help

Thanks, didnt think of that...

c6, 3126

JNSNWT 09-15-2020 05:06 PM


Originally Posted by bpu699 (Post 5441768)
Thanks, didnt think of that...

c6, 3126

Don’t feel bad. I know exactly what I’m talking about so the rest of the world should know too.

If you live in a bigger city there’s probably a bearing supply company there that might have what you need on the shelf.

I would suggest you stay with a name brand that is not made in China.

the sights 09-15-2020 05:30 PM

Hello, Check this out.

This was my project. Look at posts #s 9,29,47 and 54

dont know your bearing #s and watch snap rings

bpu699 09-15-2020 06:12 PM

Thanks folks... lots of reading :)

desertdd 09-16-2020 06:22 AM

I replaced the bearing in my water pump idler pulley a couple of years ago. Freightliner provided the parts.

jimcumminsw 09-16-2020 11:31 AM

I would refer to the Cat service and parts book for a C6/3126 engine. See attached link

Cat parts books usually list all serviceable parts which are available at a Cat dealer.

FIRE UP 09-19-2020 12:01 PM

I replaced the bearing(s) in my serpentine tensioner, the idler and the water pump tensioner. But, that was years ago and, as usual, I can't find the notes on it. I'll keep looking.

Mongobird 09-21-2020 03:47 AM

1 Attachment(s)
Here is the tensioner I pulled.

Mongobird 09-21-2020 03:53 AM

Replacing an alternator at 80,000, I found the idler bearings loose and replaced the idler (~100), and replaced the V belt pulley bearings. When I blasted the tensioner (~240)(bearing was OK) I found hairline cracks (see previous posting). I also pressed out the V belt bearings (you will need two, $13 ea). I replaced both belts, although the V belt looked just fine.

bpu699 09-28-2020 02:56 PM

Well, in case this helps someone:

Bearings were VERY rough, glad I checked. Alternator and AC were smooth...

The stock bearings are ntn 6203LU... 6$ a piece, needs 2. Had questionable rating on amazon, lots of counterfeiters...

There are better manufacturers, I went with timkin 2nse 6203 bearings, $10 each. High end, made in America...

Taking out the bearing was fun, needed to take out the circlip, and then tried a 1 ton press... no luck. Sledge and a socket worked just fine...

Threw it on a lathe, smooth the surface too...

So, 20$ all in and about 30 minutes of time...

n2zon 09-28-2020 05:22 PM


Originally Posted by Mongobird (Post 5449068)
Here is the tensioner I pulled.

Ready to go another

Mongobird 09-29-2020 01:02 AM

The bearing on the tensioner felt good, but the serpentine belt idler bearing was loose.

The water pump tensioner bearings were not a problem with a 12 ton 40yo Harbor Freight press. I think a 3lb hammer and socket would have pulled them ok. Not lots of resistance but more than a drill press will reasonably provide.

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