Hello,
Since I posted about a valve clatter like noise with my 03 Camry/ 4cyl (2AZ-FE), I think it must be related to the VVT mechanism. Reasoning to follow.
While at work, I recently examined, and disassembled a VVT unit form a Celica GT. First off, I was struck by its weight. It's all steel, and I would say about 1.5-2 pounds in weight. Interesting to note the bolts holding it together were 5 sided.
Secondly I was struck by its simplicity. Basically it was a finely machined cylinder sprocket, with a vaned rotor inside making variable chambers. It operates by a solenoid allowing oil enter the cylinder through holes at varying rates/volume, enlarging the chambers, thus making the camshaft advance a certain degree.
I am wondering if these chambers are totally empty at idle (no VVT action), allowing some metal-to-metal contact inside the VVT to happen, producing the clatter/tapping I am hearing. I also noticed if I hold a sustained 2500 rpm's in park with a fully warmed engine for 30 seconds or so, the clatter will many times disappear. Maybe some residual oil/mild VVT action at idle stops the noise?
I know Toyota says the VVT-i is continuously variable, but wonder if this means at idle? I would be interested to know what variables/parameters must be set to activate the VVT system.
Your thoughts and insights on this matter would be appreciated.