Bizarre head noise at 1000-1200 rpms...

[Onizuka]

I've taken off the valve cover to visually inspect and check to make sure nothing is loose and I cant find anything. I dont get it, there is absolutely no wierd noises from this area from 0-999rpms and 1201-7500rpms. Sounds like a spinning vibration from 1000-1200rpms. Any ideas?

[Cyberkreig]

does it happen to sound deep and have a "grrg" noise? Does it remind you of a bad bearing or a turbo hitting its housing?

If so, we have the exact same problem.

[Onizuka]

well, its more of a noise comming from the cam gears/CAS area at the front of the head.

[Hijacker]

check the cam bolt on the exhaust side. it also could be the timing chain :\ that's a very weird range for that sound to accure in

[Onizuka]

I check the camgear bolts and all retainers and brakets in the head, nothing is loose. My best guess is it has something to do with the hole the CAS shaft rides in or the CAS itself.

It could be the timing chain, but everything looked pretty good when I took the motor apart. How would I go about checking to see if the chain or guides need to be replaced?

[Hijacker]

i'm just thinking that if it stretched a bit, it could be causing a noise, but it would cause a rattle across the whole rev range.