Plug in a scan tool.
Sitting right on top of the engine.
Bottom front of engine.
locate timing chain guides.
It detects detonation in the combustion chamber(s), then adjusts the engine timing to compensate.
According to the Gates website ( they make timing belts etcetera ) the 3.3 litre V6 engine in a 2002 Mercury Villager is an ( interference engine )
I looked at the Mercury Villager Owner Guides from ( 1996 , 1999 , and 2002 ) With engine oil filter change : Each Owner Guide shows ( 4.2 U.S. quarts )
There are two.
There are two, on in front of the converters near the engine, and one after the converters, roughly under the passenger seat.
1999-2002 Villager or Nissan Quest.
1999 - 2002.
If it is defective it will need to be replaced.