Is my Cat starting to show its age? 2 months ago, I got the dreaded CATS warning and yesterday, a clicking noise after the engine warms to operating temp! It sounds similar to a slipping fan belt or a bad water pump but, with all the hardware in the way-I cannot locate the problem.....

Clicking? Like a ticking? does it change with engine revs or seem independent?

purge valve is a common cause of these (I thought mine was a lifter)

https://www.jaguarforums.com/forum/x...icking-108555/

Any symptoms with the CATS warning?

No change with RPM, noise is coming from the front-left-side of engine and is very audible while sitting in the vehicle with windows down. Once again, as you all know, there is a lot of stuff in the way and I am not ready to remove parts as yet. I have had several loose belts on other vehicles and this noise sounds close to that. The noise starts when the coolant is at operating temp!

Yes, a hard ride!!! Struts are locked in the hard setting. The air springs are working normally.

Have you considered that it could be an exhaust leak? If you have a small crack in the manifold you might not hear the leak until the metal heats and expands, and the same could apply for a gasket leak.

I located the noise, it is the belt tensioner. I now have to determine if it is a loose belt or a bad tensioner. Does anyone has the amount of travel specs for the belt?

Thanks for the tip, an exhaust or gasket leak would change with rpms.

Well, wouldn't a belt or tensioner noise also change with rpms...?

I have worked on cars, trucks, and heavy equipment for 41+ years and the noise varies with veh type, belt type, tensioner type, and powertrain. In my case, the noise got louder when in gear but not faster. A loose belt may get louder and get higher in noise-pitch like a squeal.

Anyway...I checked the belt--it is worn. Also checked the tensioner and the pulley bearings are worn (the bearings were making the noise). I have to replace both and since a few hoses are in the way, I may also have to purchase a tensioner tool to do it right.
I may also replace the idler pulley mentioned in this post:Bad bearing or water pump or ?????

Removed both the Tensioner Pulley and the Idler Pulley, found evidence of a past belt breakup wrapped behind the Idler Pulley.

Purchased 2 pulleys and 2 bearings from the local O'Rielly Auto Parts Store at a very reasonable price.
(Purchased the 2 bearings to replace the worn units and will use those as backups if needed.)


Replaced the 2 bearings, looks good as new..