There are 11 owner-reported engine complaints for the 2004 Mercury Grand Marquisin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
The contact owns a 2004 Mercury Grand Marquis. The contact stated that she noticed a leak underneath her vehicle with the check engine and coolant warning lights illuminated. The contact had taken the vehicle to an independent mechanic where it was discovered that coolant had been leaking from a crack in the intake manifold. The dealer nor the manufacturer had been notified of the failure. The vehicle had yet to be repaired. The failure mileage was approximately 150,000.
I WAS DRIVING AT A SPEED OF 45MPH ON A COUNTY ROAD IN RUSH HOUR TRAFFIC WHEN MY CAR'S ENGINE LIGHT CAME ON SIMULTANEOUSLY AS POWER OF VEHICLE SLOWED WHILE MAKING A RATTLE TYPE NOISE AND CAB SMELLED STRONGLY OF GAS. I ROLLED WINDOWS DOWN PULLED OVER WITHIN A BLOCK TO A NAPA STORE. THE EMPLOYEE TOLD ME THEY DO NOT RUN DIAGNOSTICS AND I WOULD HAVE TO TAKE IT SOMEWHERE. I DROVE SLOWLY TO A 2ND AUTO PARTS STORE 1 MILE AWAY TO RUN DIAGNOSTICS. ONCE DONE, DIAGNOSTICS IDENTIFIED A MISS-FIRE ON SPARK PLUG #2. HAD VEHICLE TOWED TO HOME AND TOOK 'HELI-COIL' OFF AND SPARK PLUG CAME OUT WITH IT DAMAGED. THE HELI COIL WAS ALSO DAMAGED. THE THREADS OF SPARK PLUG WAS FLATTENED THREE THREADS FROM BOTTOM. CONTACTED AUTO PARTS STORE AGAIN WHERE THE TECHNICIAN TOLD ME THAT FORD HAS BEEN HAVING PROBLEMS WITH THERE TRITON SPARK PLUGS BLOWING OUT ON THE 5.4L ENGINES THAT THEY ONLY SCREW IN 3 THREADS INTO THE HEAD OF THE ENGINE AND THERE WERE PENDING LAWSUITS. THE NEXT DAY I CALLED FORD DEALERSHIP AND SPOKE WITH THE ACTING SERVICE MANAGER. "HE TOLD ME THERE WAS NOTHING HE COULD DO ABOUT IT AND I SHOULD CALL CUSTOMER CARE OF FORD: 800-392-3673. I DID AND REP. TOLD ME THERE WAS NO RECALL AND MY VEHICLE AND IT WAS OUT OF WARRANTY AT 101,100.MI. THERE WAS NOTHING THEY COULD DO. IN THE EVENT THERE WERE TO BE A RE-CALL TO SAVE MY RECEIPTS AND FORD WOULD REIMBURSE ME. I READ ABOUT THE PROBLEMS THAT MULTIPLE CUSTOMERS WERE OR HAD HAD REGARDING THE SAME PROBLEM WITH A FEW VEHICLES LEAKING GAS WITH THE PROBLEM. THIS IS ALL HAPPENING WHEN THE CARS, TRUCKS AND SUVS EXCEEDS 100,000MILES. I FEEL THIS IS NOT ONLY POOR MANUFACTURING OF AN INFERIOR ALUMINUM CASING AND SPARK PLUG AND ALSO NOT ENOUGH THREADS TO HOLD THE SPARK PLUG IN SAFELY. TO HAVE IT JUMP OUT ALLOWS GAS TO ALSO BE EXPELLED ONTO THE CARS REMAINING PARTS AND VAPORS COULD IGNITE CAUSING THE CAR TO POTENTIALLY CATCH FIRE.
TL* THE CONTACT OWNS A 2004 MERCURY GRAND MARQUIS. WHILE DRIVING 30 MPH, SMOKE EMITTED FROM THE ENGINE COMPARTMENT OF THE VEHICLE. UPON INSPECTION, THE CONTACT NOTICED THAT THERE WAS NO COOLANT IN THE VEHICLE. THE COOLANT WAS REPLENISHED AND THE VEHICLE WAS TAKEN TO AN INDEPENDENT MECHANIC WHERE IT WAS DIAGNOSED THAT THE INTAKE MANIFOLD HAD FRACTURED AND NEEDED TO BE REPLACED. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS UNKNOWN.
TL* THE CONTACT OWNS A 2004 MERCURY GRAND MARQUIS. THE CONTACT STATED THAT THE EXTERIOR HEADLAMPS INDEPENDENTLY FAILED. THE CONTACT STATED THAT THE HEADLAMPS WOULD SPORADICALLY WORK AFTER A PERIOD OF TIME. THE VEHICLE WAS NOT DIAGNOSED NOR REPAIRED. PRIOR TO THE FAILURE, THE INTAKE MANIFOLD LEAKED ANTI-FREEZE. THE VEHICLE WAS TAKEN TO THE DEALER WHERE IT WAS CONFIRMED THAT THE INTAKE MANIFOLD NEEDED TO BE REPLACED. THE VEHICLE WAS REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURES. THE FAILURE MILEAGE WAS 96,794.
TL* THE CONTACT OWNS A 2004 MERCURY GRAND MARQUIS. THE CONTACT NOTICED THAT THE VEHICLE CONTINUOUSLY LEAKED COOLANT. THE VEHICLE WAS TOWED TO THE DEALER WHERE THEY STATED THAT THE INTAKE MANIFOLD NEEDED TO BE REPLACED. THE VEHICLE WAS REPAIRED. THE MANUFACTURER WAS NOTIFIED, BUT DID NOT DISCLOSE THAT THE PART WAS MODIFIED FROM PLASTIC TO METAL. THE CONTACT EXPERIENCED MULTIPLE LEAKS BEFORE THE PART WAS MODIFIED TO METAL. THE APPROXIMATE FAILURE MILEAGE WAS 85,000. REMAILED 08/18/14*LJ UPDATED 9/18/14*CN UPDATED 02/11/2015*JS
I HAD WHAT SEEMS TO BE A SIMPLE COOLANT LEAK BUT IT TURNED OUT TO BE THE PLASTIC INTAKE MANIFOLD CRACKED. PUTTING A PLASTIC PART ON TOP OF A MOTOR SEEMS TO ME A FAILURE OF ENGINEERING ON THE PART OF FORD. I DID NOT RECEIVE ANY CALL BACK FOR THIS PART. I DID SOME SEARCHING ON THE WEB AND FOUND THAT MANY FORD OWNERS HAD THE SAME PROBLEM. I PLAN TO CALL FORD COMPANY ON MONDAY. DO YOU HAVE ANY INFO FOR ME ON THIS SUBJECT. THANK YOU. *TR
TL* THE CONTACT OWNS A 2002 BUICK RENDEZVOUS. THE CONTACT STARTED THE IGNITION AND THE TEMPERATURE GAUGE DISPLAYED A HOT LEVEL READING WITH THE ILLUMINATION OF THE COOLANT WARNING INDICATOR. THE ENGINE BEGAN TO OVERHEAT. THE VEHICLE WAS TAKEN TO AN INDEPENDENT MECHANIC WHERE THEY REPLACED THE HEAD GASKET. THE VIN WAS UNAVAILABLE. THE FAILURE MILEAGE WAS 96,000.
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! *TR
INTAKE MANIFOLD CRACKED, NEEDED REPLACEMENT. THIS IS A PLASTIC COMPONENT WHICH IS NOT DESIGNED FOR COLD WEATHER CLIMATES. THIS IS THE SECOND TIME (SECOND CAR) THAT THIS HAS HAPPENED TO. *TR
WHEN DRIVING AT LOW SPEEDS, THE VEHICLE WOULD SURGE FORWARD WITHOUT WARNING. THE CONSUMER WILL TAKE THE VEHICLE TO THE DEALERSHIP FOR INSPECTION. PLEASE PROVIDE ANY FURTHER DETAILS. *LA *TS
CRACK INTAKE MANIFOLD BECAUSE IT'S PLASTIC. I HAD TO PAY FOR THE REPAIR AND I WAS NOT AT FAULT.*AK
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 25, 2026