My timing chain sounds loose. can it be adjusted or should it be replaced? 2003 nissan altima 2.0

If its noisey all the time it will need replacing possiblie need guides&new hydrulic tensioner

If it is running loose for a long time and is worn then should be replaced as soon as
But if the tensioner has come loose which it shouldn't have then an inspection of the links will further tell you if it should be replaced.There are ways to inspect the timing chain.This is a rough guide.

Timing Chain and Sprockets Cleaning and Inspection

1. Clean the components with cleaning solvent.
   Caution Wear safety glasses in order to avoid eye damage.
   
   
2. Dry the components with compressed air.
   
   
   
3. Inspect the timing chain for binding or wear.
   
   
4. Inspect the camshaft and crankshaft sprockets for:
   • Worn teeth (1)
   • Damaged teeth (2)
   • Chipped teeth (3)
   • Womy timing chain sounds loose. can it be adjusted - tiftogif(2).gifeen the sprocket teeth
   
   
   
   
5. Inspect the crankshaft sprocket kemy timing chain sounds loose. can it be adjusted - tiftogif(3).gif
6. Inspect the crankshaft sprocket oil pump drive splines for wear.
   
   
   
7. Inspect the chain guide (232) for the following conditions:
   • Loose metal inserts (1)
   • Cracking (2) in the chain contact area
   • Excessive grooves (3) in the chain contact area Grooves 1 mm (0.040 in) or less in depth are to be considered normal wear.