Originally Posted by e92zero
^M3PO, it's possible there are 2 separate problem as mose101 pointed out. The valve is the cheaper and easier fix so I figure it doesn't hurt to do that first and I do worry that if the valve indeed is bad, it will eventually damage the VANOS unit over time.
Found the torque spec. It's 15 Nm. I will try to replace it and see if it fixes it and report back.
That's likely the case. Further back in this thread, I remember a member said that they replaced the check valves and it didn't solve the issue.