im new on here. i have a 2001 audi a6 quattro 2.7t 6 speed. I rearended somebody and smashed the front end of my car and it broke the timing belt cover and the timing gear is bent, i think its out of time because it sounds like the passanger side valves is hitting the pistons and it dies (wont even idle or stay running). If the valves are bent do i need to replace the valve guides?

would it be cheaper to buy a used head or redo it all?

 

I would suggest replacing the timing belt, roller, tensioner and valves to ensure the ones currently are not bent to prevent further issues after the timing belt kit is replaced.

 

ok more information is needed before you go out and get just a timing belt kit and some new valves. You say you the camshaft gear is bent. to me that would indicate most likely that the shafts have been damaged as well. In my opinion if you have the know how to do the job yourself replacing everything can be done, with the proper tools (replacing all that will require quite a few special tools). however if you take it all apart and find that the camshafts are bent as well, i would look for a replacement head. Side note if you do decide to replace the valves yes i would replace the guides as well as the cam chain tensioner gasket and half moon.
Good Luck