Hello, all
I've been posting quite often lately due to some work I've done on my 99 XJR. I had the supercharger off and changed the oil and put in a solid coupler. It seems that every time I'm at idle while in gear, there is a grinding-like noise from the engine. I belive it to be from the supercharger because I can hear it come from that general area. If I am in park or neutral, the grinding noise goes away. If I put it in reverse or drive, the grinding noise comes back. If i am in drive or reverse and i rev it above idle, the noise goes away. So only at idle when I'm in gear, does it do that. I put a new belt on with the correct size and did not change the sound at all.

Any ideas?
Should it be of serious concern?

Here are some videos but they don't really capture the sound:
https://drive.google.com/file/d/1bQ-...w?usp=drivesdk

https://drive.google.com/file/d/1phs...w?usp=drivesdk

https://drive.google.com/file/d/1iIK...w?usp=drivesdk

Thanks.

 

Try to track down the noise with a mechanics stethoscope or at a pinch a long screwdriver.
I have much the same noise from my s/c and just live with it at the moment. Too many other things going on in the home garage (‘65 ‘S’ being rebuilt)

 

I understand that the grinding noise came after you did the work on the supercharger and was not present before. If this is the case, then it could be caused by the solid coupler. I have read that solid couplers (maybe not all) will make the supercharger noisier but there was no description of what kind of noise this will cause. The way to diagnose is to remove the SC belt and run the engine.

 

I had a similar noise last Spring and it was one of my neoprene seconary tensioner caps that had decided to visit the oil pan and the chain was rolling across the metal nub. It would usually happen under load. I thought it was my SC, since I had recently done the oil and that's where the noise seemed loudest. It was my passenger side one.
+1 on the stethoscope (which is how I found it) and another +1 on the belt ideas.

 

If I get the chance, I'll do what has been suggested, but since it's only there at idle when in gear, I doesn't bother me much. Good suggestions though.

Thanks.

 

Just to follow-up with this:
I changed the solid coupler I had to the original torsion coupler that was originally in there (new of course), and the noise is not there anymore.

If anyone has similar issues, then i would recommend checking the condition of the coupler.

 

 

 

Glad to see you found the culprit man!