BDE Performance VTC Gears

Stock VG30DE(TT) variable Valve Timing Control (VTC) intake sprockets are non-serviceable sealed units that are notorious for leaking oil and making noise.  Oil leakage occurs because the rear cover can become loose and rotate independent from the sprocket, this ruins its o-ring and eventually leads to an oil leak.  The noise is typical with aftermarket higher-pressure valve springs that cause the cams to over-rotate on every valve-closing event.  This over-rotation causes the VTC piston to screw itself into the VTC helix and overpower the piston return spring.  As the cam continues to rotate, the valves close and the valve spring pressure diminishes to the point where the return spring slams the piston back to its stop creating the audible tick that is indicative of a noisy VTC.