The book says at 60,000 miles. I have 200,000 on my 1995 and I haven't changed it. So, as long as you are not having problems, I'd leave it be.
How do you replace the timing chain on a 1994 mercury grand marquis
Chain
The 2005 Mercury Grand Marquis , 4.6 liter SOHC , V8 engine has ( 2 ) timing chains ( 1 timing chain to each cylinder head )
In a 1997 Mercury Grand Marquis : ( YES ) the 4.6 liter Single Over Head Cam , V8 engine has ( 1 timing CHAIN to each cylinder head , so there are 2 timing CHAINS )
Worn timing chain?
The 4.6 liter SOHC , V8 engine in a 2000 Mercury Grand Marquis has ( 1 ) timing CHAIN to each cylinder head ( so there are two timing CHAINS )
NO belt in the 302cid engine of a 1988 Mercury Grand Marquis. it is a chain with gears
The timing chain can not be repaired, it must be replaced. To do this you must disassemble the front of the engine. The fan, belt, dampener, water pump and timing chain cover must be removed to gain access to the chain.
On a 2002 Mercury Grand Marquis : No , the 4.6 liter Single Over Head Cam , V8 engine has ( 1 timing CHAIN to each cylinder head , so there are 2 timing CHAINS )
Timing chain.
In a 1989 Mercury Sable : Both the 3.0 and the 3.8 litre V6 engines have a timing CHAIN
The 3.0 liter V6 engine in a 2006 Mercury Montego has a timing CHAIN