Its a inconsistent humming sound. Start's after engine has warmed up bit but not to operating temp. Ive stethoscope'd the valve cover's, alternator and ps pump and Im pretty sure its in cam gear / timing belt area.

Hoping some folk might have experienced the same thing. Car is going out of town for tuning soon and it has me worried a bit. Several friends think it may be a over tightened timing belt but its sounds nothing like the vids in posts on over tightened t belts. Engine sat a few years after build but all parts in there are new. Has greddy t/ belt, kelford cams, cam gears and aftermarket balancer, just to throw that out there. Only other thing I can say the car is doing that not right is squeaky belts on initial start up.

The last rb25 in there made a similar noise and it was internally stock so wondering if this is common with this engine.

Thanks for any help