Idler

[Dan Stussi]

I am wanting to replace the Serpentine Idler on my CAT 3126 as the bearing is starting to make some noise. When I look at the area where you should see a bolt head, it appears there is dust cap over it. A neighbor who is a fleet mechanic for Pepsi has said he has never seen that, but he agreed that is what it looks like. The MH has only 54,000, so I believe it be the original Idler. Before I punch a hole in the cap I am curious if any of you have run into this, and what did you do to remove the cap. FYI, by Idler I am referring to the one between the fan and alternator, not the tensioner.

Any help is appreciated

Dan

[Steve Huber Co-Admin]

Dan,
If you are getting a singing sound from it, try spraying a small amount of water on the ribbed side of the serpentine belt. If the singing stops, it's most likely the belt, even if it looks good.
Steve

[Gerald Farris]

Dan,
The cap can be just popped out with a small sharp chisel. Under it you will find two sealed ball bearings with snap rings to hold them in place. The bearings are readily available at Napa.

Gerald

[Dan Stussi]

Thanks for the response Steve and Gerald. Gerald, will I find a bolt under the cap that holds the idler in place? I just don't want to damage anything with the chisel. I changed the belts last year when we bought the MH  and snapped off one of the pivot hold down bolts for the water pump. After my son and I spent most of day fixing that I am a tad bit gun shy.

Dan

[Gerald Farris]

Dan,
Yes, there is a bolt through the center of the bearings that mounts the idler pulley to the engine bracket. However, you should be certain that you have bad bearings in the idler before you replace them. A bearing failure at such low mileage is not common.

Gerald  

[Steve Huber Co-Admin]

Dan,
On my Marquis (C12) the bolt that holds the idler had a reverse thread.
Steve

[Dan Stussi]

You guys are great.   Thanks for the answers. My neighbor did say that it felt it was good for at least another year. It just feels dry when you spin it, but it does run true. What caused me to check it was my alternator positive senser wire was not making a good connection so it was fluctuating all over the map which caused the belt tensioner to load and unload constantly when the alternator was thinking it needed to make higher charge voltage. I took the belt off after fixing the senser wire to check all bearing/pulleys that the serpentine belt drives. The idler was the only one that caused me some concern.

I am printing all your help out and putting it in my service binder.

Thanks again,
Dan

[Steve Huber Co-Admin]

Dan,
If you've got the belt off and the idler bearing is feeling a bit "stiff", I'd go ahead and change it now. As Gerald noted, NAPA has them. I paid about $44 for mine earlier this year.
Steve

[Carol Moffett]

We had the belt and idler pully replaced at BCS last summer but the squeal is back.  It squeals for the first 1/2 hour after cold start.  We are at a shop and they said that if they replace a belt and not the tensioner, the squeal always comes back shortly.  The tensioned has seen better days so out it goes.  I will update on the results.
Keith

[Larry Dedrick]

To All:
           Just to add my experience to belt noise. I had a squeal from my belt and two different facilities tried to remedy the problem and never did correct it.
           One day, I was doing preventive maintenance around the engine and decided the noise was coming from my AC compressor. With further inspection and pondering, I decided to check the pulley alignment on the compressor and sure enough. it was not aligned properly. I noticed the washers that are used as shims were at opposite ends on the mounting bolts, so I removed the one bolt and positioned the two washers at the opposite end and no more alignment issue and the squeal has never returned. The compressor was replaced at some point in time before we bought the coach and who ever did the repair did not get the washers back where they belonged.
          
                     Larry D