About six months ago I heard a low frequency knock from the RH side of the engine. Just audible at idle, standing beside the engine with the hood up.
I thought that it was the alternator bearings on the way out (wishful thinking!).
Recently I got a stethoscope and hunted around. I cannot target the noise. The knocking increases in frequency with higher engine revs before being drowned out. I can hear it through the alternator housing and RH belt idler.
I was thinking of taking off the serpentine belt and briefly running the engine to eliminate accessory noise. Will this damage anything?
Am I looking at main bearing damage?
Thanks again,
Dan

 

I took off the drive belt and discovered that the knocking is coming from the idle wheel on the tensioner. Much relief!
Is the tensioner a simple unbolt?

 

Yes, tensioner is a common problem and a easy fix. Be prepared. The other side will probably go soon as well.

http://www.motorcarsltd.com/AJ82266.html

 

yeah mine squealed like a banshee for months when cold, towards the end it screached 24/7. Sad stuff,

HOLY JOE that thin is $77 now on your site? used to be aruond $44 or so I thought, talk about a jump in price ken what gives?

 

It seems that we both have the same problem only mine is on a 99xk8. Shame on Tom not to tell you or me that!!!! Take a look at my post https://www.jaguarforums.com/forum/s...ad.php?t=29520 I replaced the belt for the second time the other day and still have the problem. I am going to replace the tensioner and idler tonight and see what takes place. I will let you know!

 

be aware that picture posted on motorcarltd is not the pulley you will get, you will get a lipless revised version right ken

 

That is correct. The updated, metal pulley does not have a lip on it.