Salim: I agree, the only thing that changes b/w start-up and warm is the water pump...BUT, w/ the MS that seemed to be the quietest part.

Code: I tried to place the MS on the bolt of the idler pulley...yikes, caught the belt and about blew my eardrums out. The problem was likely that I didn't have a short probe - longer ones seem more difficult to control.

Anyone bent the valves on an RX? I've considered driving it until the problem gets worse and, usu., easier to identify.

 

Forgive me for chuckling, the MS does kinda magnify the sound doesn't it? I much prefer the MS but some people just use a LOOOONG screw driver or rod of some type. Probably not as loud but will still magnify the sound when you put it right up to the ear canal.

 

I swallowed a flat washer down my intake when I was done doing my knock sensors. It was one of those loose ones holding the lower plenum down. (Its funny, because some of the washers were made holding the nuts, so they couldn't come apart. I KNEW there was one missing when I was assembling, but couldn't find it.) When I started the car, what a noise! Good thing it was a soft washer! I would have broken a piston or connecting rod if it was a hard one.

-But I think I bent a valve, number 5 cylinder. because I had a knock from the engine after I removed the washer for a long time. It seems like the noise is now gone . But yes, I THINK I have a bent valve. Car still runs great. RX 300's are built like tanks!

Have you ever had the back valve cover off? Mine was full of hard sludge, I wonder if its blocking some of your oil returns.

 

Final Update...went to a Lexus certified shop, and was told the same thing! That although it was "not right" they weren't sure what the problem was (although they were pretty sure it was in the timing area). The new shop changed out the idler pulley w/ one on hand = no change in sound. I picked it up a few days later after the tensioner was changed (it has never been changed, 105K miles on this '02), and the sound is quieter, but not gone. Who know's? I'm over it and will drive it until that particular part, whereever it is, goes bad. Out another $380, but that is child's play for what the shop could have charged.

 

Anything is POSSIBLE, but in checking the belts on my wife's new 2011 Camry, I did notice 2 or 3 parts (including the W/P) that definitely said Aisin on them, so have some doubts about the accuracy of that information.

 

Code - I think you're right there re: Aisin.

I am confusing my wife's RX w/ my '00 Landcruiser. The IH8MUD forum is where I read that either the fan clutch or w/p no longer says Aisin...sorry about that!