I recently replaced the idler pulley due to the squeaking eventually occurs as the bearing gets old and dry. I used a piece of hose as a megaphone to isolate the squeak while the engine was running. Replacing the idler pulley did eliminate the squeak.
Coming from a bicycling background I have rebuilt titanium crank bottom bracket bearings rather than pay the high dollars necessary just to stop a squeaking/creaking bearing. So why not see if I could do the same thing with the idler pulley that I just replaced?
Maybe it's just me, but I tend to save old parts just in case I need them in an emergency. I know they aren't that expensive. But it might save some time in ordering and waiting for a new pulley. Or, just to troubleshoot and repair this bearing before going on to isolate further.
Thought that I would share what I did and add a small piece to this knowledge base that I have used to do repairs on my Ti.
First, the idler pulley as it was pulled.
These are "sealed" bearings. But that doesn't mean that they can't be cleaned and repacked. The sealing ring is made of rubber and is fixed in-place by a lip along the outside of the bearing race. I used a small flat blade jewelers screwdriver to gently pry this ring out from the outside. You can see it partially removed here between 12:00 and 3:00.
Completely removed. The grease is partially gone and there is some dirt and grit floating around in what grease is left. The bearing did spin easily though.
Backside of the sealing rings. Looks like some sort of carbon/graphite insert to make the rubber a bit less compliant.
A closer look at the exposed bearing. Old grease and grit along the outside race.
Clean out the old grease and dirt. Anything that will dissolve the grease will work. I had carb cleaner available and is was a in a spray can so that helped dissolve and blow the stuff out.
Repacked bearing. I just pushed the grease in using a wooden chopstick until I saw it coming out the of other side.
Then put some grease in on the other side and spun it a couple of times to get everything lubed. Do not over pack the grease into the bearing. There wasn't a whole lot in there to begin with and I suspect that it will sling the excess all over the place once it is in use.
Clean up excess and reinstall seals by placing the seal behind the lip and sliding your finger around the bearing while pressing down.
I cleaned up all of the other dirt on the outside and put the idler pulley back in the box and stored in the spare parts bin.