My RX developed a tick around 95K Miles. I hear it all the time but it is most pronounced at higher engine RPM. It seems to be coming from the left rear passenger side of the engine. I suspect it is either valve train related, or an injector.

Has anyone had the experience of a repair for clatter. I have heard complaints about injectors but this sound seems slightly louder than that.

 

May want to take a video/audio of it, as sometimes weather/type of oil used can affect the engine sound. I know using Castrol 0W30 as I am right now as really quieted down the engine clatter.

 

The RX300 does have adjustable valve clearance, albeit not exactly easy to adjust. I've adjusted valves on previous cars, although not on a car that uses shims for valve adjustment. My guess is the clatter will be solved by normal valve adjustment, but that's only a guess. I had a friend with a Jaguar XKE years ago and he used to have to shim his valves every year!