Prolonging the Life of Idler Pulleys
This weekend I changed the serpentine belt on my Jeep. Serpentine belts live up to their name and take a tortuous path through the drive pulley system of your motor. To keep a serpentine belt properly tensioned and to deflect it away from the areas it shouldn’t contact, a system of idler pulleys is used. Idler pulleys have a flat, smooth face against which the back side of the belt runs. An idler pulley typically contains a sealed ball bearing, pressed into the center of the pulley, on which the pulley spins. After many thousands of miles, perhaps 60,000 (depending on driving conditions), the factory-packed grease will be pretty dry, and the bearing will begin to fail. If your bearing has rubber seals, you may be able to carefully pry them out with a couple small screwdrivers and pack the bearing with fresh grease. I performed this operation this past winter on the idler pulley next to the air conditioning pulley when it began chirping for a few seconds when started in the morning, and this weekend on the remaining idler. After cleaning the outer surfaces of the seals, I carefully pried them out of their seats and repacked the bearing with white lithium grease. Then I pressed the bearing seals back into place and reinstalled the idler pulley.
Update: 8/22/08 So far (8 months for one and only a dozen days for the other), all is well.
How Do You Check for a Bad Belt?
A couple of months ago, I had my Jeep at the dealer to diagnose a fuel problem. You probably know that when you take a vehicle to a dealer, they usually look it over pretty carefully, looking for other work they might be able to perform for you. One of items on my inspection was “belt cracked.” Just looking at the wide surfaces of my belt while it was installed, I thought it looked pretty good and that the dealer was just trying to sell me a bill of goods. But, because the weather is hot and I hate the thought of being stranded in the hills with a cooling problem, I decided to replace it anyway. It wasn’t until I got the belt off and could look at its thin edge closely while bending it, that I could see the small cracks beginning to develop. I had a momentary pang of guilt for my earlier bad thoughts about the dealer’s honesty. I learned a lesson about how to check for a bad belt.