NHTSA Complaint #10173090 — 2003 FORD NAVIGATOR

2003 FORD EXPEDITION XLT WITH 5.4 LITER TRITON V8 ENGINE WITH 59,000 MILES. THE VEHICLE IS WELL MAINTAINED AND NOT ABUSED. THE #3 SPARK PLUG WAS BLOWN OUT OF THE ALUMINUM CYLINDER HEAD DURING DRIVING AT APPROXIMATELY 5 MPH. THIS EVENT WAS PRECEDED BY A TAPPING NOISE WHICH OCCURRED OVER THE PRECEDING TWO WEEKS. THE NOISE WAS SIMILAR TO A NOISY VALVE LIFTER. THE ENGINE HAD THE ORIGINAL FACTORY INSTALLED SPARK PLUGS THAT WERE NEVER REMOVED, REPLACED OR SERVICED. THE FACTORY CHANGE INTERVAL ON THE PLUGS IS 100,000 MILES. SPARK PLUG BLOW OUT RESULTED IN THE THE NEED TO REPLACE THE CYLINDER HEAD AND COIL PACK. INSPECTION OF THE OLD PART REVEALED THAT ONLY 4 TO 5 THREADS WERE PROVIDED TO RETAIN THE SPARK PLUG. INSPECTION OF THE NEW REPLACEMENT HEAD REVEALED THAT 9 THREADS ARE PROVIDED TO RETAIN THE SPARK PLUG. FORD KEPT THE OLD PARTS. THIS IS AN OBVIOUS DESIGN FLAW THAT HAS BEEN CORRECTED BY AN IMPROVED NEW HEAD. THERE ARE HUNDREDS OF THOUSANDS OR POSSIBLY MILLIONS OF VEHICLES ON THE ROAD WITH THIS DEFECT. THE TRITON ENGINES WITH CYLINDER HEADS HAVING THIS DEFECT WERE USED IN FORD AND LINCOLN SUV'S AND TRUCKS FROM APPROXIMATELY 1998 TO 2003, INCLUDING HE POPULAR F150 PICKUP. AFTER THE FAILURE OCCURRED THE ENGINE WAS RUNNING VERY ROUGH, MAKING A LOUD NOISE AND COULD NOT BE SAFELY DRIVEN. THE VEHICLE STALLED. *NM