One problem related to engine has been reported for the 2004 Mercury Grand Marquis. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Mercury Grand Marquis based on all problems reported for the 2004 Grand Marquis.
2004 Mercury marquis 4. 6 l engine. Spark plug blew out while driving, creating significant safety hazard because of loss of power and presence of combustible gasoline fumes. This is a safety hazard!.