Replaced serpentine belt and belt tensioner pulley. When I cranked engine on without serpentine belt, noise was gone, when I replaced with new belt and new tensioner pulley noise retuned. I put a video on YouTube. If anyone cares to take a look and give their opinion of this here in the link:



Thanks in advance. Currently, the battery warning light is coming on. Alternator has been checked for proper voltage and passed.

 

If u remove the belt check the idler pulley near the bottom of the engine. It should spin freely they are cheep pulleys and go bad. I had the same problem on my car

 

I just listened to your u tube link. That sound is the same sound I had. Definitely check the idler pulley it is just a pulley that bolts to the engine. The pulley itself is the same size as the pulley on the tensioner about three in across. It cost about 40 dollars. If it is that I would change the pulley on the belt tensioner also. The belt tensioner pulley is the same type as the idler pulley. so they probably have the same life before they go bad

 

You said you replaced the belt tensioner pulley (right arrow on the attached thumbnail). Now replace the idler pulley (left arrow on the attached thumbnail) and I would venture a bet your problem will go away.

This is a very typical sound that I had on other cars that had failing idler/tensioner pulleys (dried up bearings)

 

Examine the pulley on the lower right side of your video screen right after start up. Looks like it's wobbling.

 

Have you tried listening with a mechanic's stethoscope? This should pinpoint the source of the noise.

 

How much of an ordeal is it to tackle this job? What is the suggested strategy to access the pulleys?

 

I replaced the drive belt on my XJR recently. I took the radiator fan assembly out of the vehicle and that gave me lots of room to work with. This additional room will allow you to remove the idler and tensioner pulleys with no trouble. DIYer doable with lots of time and patience.