Bearing Noise on Belt Tensioner Pulley

[Duner]

Well it started out as a "eeee eeee" engine noise at start up when cold about a year ago. It would last about a minute and then go away. A few months ago I noticed it was taking 5 or 10 minutes longer before it would quiet down. Then a couple of weeks ago the noise did not go away at all..... time to change before the bearing flies apart. I have just over 40,000 miles on the engine.

Access to the tensioner is quite easy from under the engine. Using a 3/8 in ratchet on the serpentine belt tensioner to allow the pulley to free wheel, I could feel just the tiniest bit of wobble on the pulley. Using a 13 mm wrench, I removed the pulley. The sealed ball bearing looked good but I could see where internal grease had been seeping out.
On my 2004 W22, the stock bearing is Japanese NSK 6203-DUL1. The NAPA equivalent is 6203-2RSJ made by SKF and cost me $11.
I used a large socket (maybe 1-3/8 in, not sure) to pound out the old bearing, and then "gently" tapped in the new bearing. The only tricky part was to get the new bearing seated perfectly square. It took me a couple of times to mount, spin and test for no wobble. If I had a vise to hold a bolt to do a test spin it would have been quicker than crawling under the engine and mounting for testing.
Now she's runnin' nice and quiet again and I'm a Happy Camper with no down time.
-Bill

[Brazel's RV Performance]

Nice DIY Bill!