I have an 02 XJR and, when I'm not giving it throttle, the engine seems to make a loud whining sound. The sound isn't consistent while driving and comes and goes, but seems to be consistent while at idle. While driving, it first makes a loud whining sound followed by the same sound at a lower pitch and then it goes away. I left the car running and opened the hood and noticed that the sound seems to be coming from the supercharger. Has anyone else experienced this before? I apologize if this has been covered already, but I searched the forum and didn't find anyhting.

 

Are you able to remove the supercharger belt? Simple job - this would give you the opportunity to isolate the supercharger from the accessory belt, its parts and pulleys - the engine will run fine without the SC. If the noise is still present you can discount the SC and dig deeper into the issue on the accessory side (Alt, power steering, air con pump etc...) If not it could be the case of a supercharger snout rebuild.

 

My supercharger "seems" to be making a noise sometimes as well. I had assumed it was the sound of air in the intake tube because it's a low wooshy sound that comes and goes. It can happen at low RPM while driving or sometimes sitting in park. I can't really isolate it with a stethoscope but it seems to be coming from the front of the supercharger (pulley end).

If it's a snout issue is that a fairly straight forward fix?

I'll remove the belt this weekend and see if that tells me anything, diagnostically.

 

I finally got around to removing the supercharger belt today and it seems that the supercharger is not the problem. When I removed the supercharger belt, the engine whine was a steady tone the entire time the engine was running. With the belt on, the sound comes and goes at idle. Guess it's time to either dig deeper or go see a mechanic!

 

Sounds more like a pulley bearing (idler/tensioner) or one of the auxiliary units, an engineers stethoscope might locate the noise faster and cheaper than taking it somewhere! A long screwdriver placed on each part while leaning your ear on the handle will tell you what is making the noise.

 

 

I once had it with a clapped out power steering pump ...