I have a 93 Z28 with auto trans. When I start the car and let it idle there is a grinding noise coming from the trans. The fluid looks clean, and it shifts and drives well. After a few mins the noise goes away. What can it be? Do I need to open it up? Thoughts?
Let me change that... Its not really a grinding noise - it sounds like something is rubbing the bottom of the pan.

 

Well I figured it out. The filter had actually wiggled itself off and was vibrating against the bottom of the trans pan. I put a new filter on and everything seems to be back to perfect...