when I turn on my 03 z manual and press the clutch all the way it's starts grinding only when is cold ..then when driving and I shift into 2nd it grinds ??any ideas ??

 

If you've never drained and changed your MTF, now would be a good time. Stick with OEM Nissan fluid. Buy it from Courtesy Nissan and you'll save some $$.

Also, check your clutch master cylinder reservoir and make sure it isn't low. If it is, carefully use a syringe to suck out the old fluid from the cylinder and replace it with some fresh Prestone DOT-3 brake fluid. Old brake fluid absorbs H2O over time and loses it's ability to do its job. What's described above is a poor man's clutch flush, but it does help and it doesn't require you to bleed the system.