One problem related to loud engine noise has been reported for the 1999 Mercury Grand Marquis. The most recently reported issues are listed below.
While driving 55 mph a loud noise was heard coming from the front. Vehicle then stalled. Consumer restarted the vehicle and pull over. Then, consumer noticed that oil leaked underneath. Consumer drove vehicle to the dealer for inspection, and mechanic determined that the cylinder head cracked, and needed to be replaced (20794 miles). Recently the consumer noticed another oil leak which appeared to be the same as that from the first cylinder head. The service manager inspected the vehicle and concluded that oil was leaking from the cylinder head again (59700 miles).