How do I tighten the belt on a 2010 Acura TL?

 

By replacing the tensioner.

 

Welcome to the forums.

This thread has been moved from the Third Generation TL (2004-2008) > 3G TL Problems & Fixes Forum to the appropriate subsection so you can hopefully get more help.

 

I assume you mean the serpentine belt that drives the accessories. Why do you think it needs tightening?
As stated above, the real root cause may be the tensioner.
Replacing the belt itself is fairly easy. There are discussions in other threads about the tensioner.
Do a search.

 

The belt does stretch slightly over time. A new belt might be somewhat tighter but this is not always the case.