Here's a solution to this vexing, known and common issues Lexus should've stepped up for IMH. The noise can be long and loud or softer and shorter 1 to 4 seconds. It sounds violent and destructive. I just had this thought and it works. The problem is caused by my a delay in oil pressure, I believe and gears don't fully engage, causing them to grind. Solution: start it just for a moment and turn it off. When you restart it seconds later, no grind. Oil pressure is up, gears now fully engage. Basically the short start primed the pump, I think.

Would love to hear from others who have this issue, what did you do? Did you replace the cam gears? How much did it cost? Did it stop the problem? Did the cam gears break apart and cause other damage? Did the engine ever fail because of it? How many uears did the noise last before engine failure? I was thinking of doing this horribly costly job, but no more.

Thanks!

 

There are no cam gears it is a chain. The start up noise can be caused by the chain tensioner not engaging due to start up 0 oil pressure or being wore out. The noise goes away as the oil pressure forces the tensioner into the chain. A lose chain makes noise.

 

Yes, and the chain tensioner can be replaced in 20 minutes.