2005 Camry w/4 cylinder and auto trans. About 2,000 miles ago I noticed a slight "rattling" at idle, when cold (45-50 degrees). After a couple "warm up " minutes the sound went away. It was an erratic rattle, not having a distinct cadence. Sounded a lot like other motors with a belt idler pulley going south. Just got a text from my wife stating that the rattle has evolved into a higher pitched continuous "knock" that she compared to spark knock (bad gas). She said there are no warning lights on dash and that the car still runs ok. I told her to get home and park it. I'm at work and am having no luck locating the service manual that I had downloaded. I vaguely remember reading that this motor has a timing chain, as opposed to a belt. Is it possible that I have a tensioner, or shoe, that has given up? The car has 165,000 miles on it and has had 5,000 mi oil changes since we bought it with 35,000 miles on it. Other than warping brake rotors, I have had no problems with it. Is there a recommended mileage interval for timing chain and/or tensioner replacement? Do my descriptions sound commonplace? Thanks in advance for any help.

 

There is no recommended period replacing the timing chain or tensioner.

It is possible the guide on the tensioner wear out and the chain rattles.

The VVTi intake camshaft gear can also rattle.

Use a section of rubber hose as a stethoscope to narrow down the area of the noise.

Make sure noise is not a rod or bearing knock from inside the engine block.

 

Too busy to do the work, I took the car to a very trusted and previously visited independent shop. Within a few hours, a phone call revealed to me that two separate issues were at play. A bad water pump and a broken spring at the serpentine belt tensioner. 160,000+ miles and this is the first "slightly" major repair? I love my (wife's) Camry!

 

Good job. Thanks for posting back with the fix.