Which engine? It is different between the 2.7 and the 3.5. The 3.5, loosen the bolt on the idler for the AC belt, then from under the car back off the belt tension adjuster until you can remove the belt. Reverse process to install, tension should be about 1/2" total play in belt after adjustment.
Closest to serpentine belt
The 3.5 litre V6 engine in a 2004 Dodge Intrepid has a timing BELT
Change at 105,000 miles. Warning: (Interference engine, if the belt breaks serious engine damage will occur)
go to local library they have chilton and haynes repair books
Replace
3.3L has a chain. 3.5L has a belt.
Timing belt.
2.7L - chain 3.2L and 3.5L - belt
Belt.
has a timing chain
In a 2004 Dodge Intrepid : The 2.7 litre V6 engine has a timing CHAIN ( also , the 3.5 litre V6 engine has a timing BELT )
replace the seat belt