NHTSA Complaint #10361624 — 2003 FORD F-250 SD

TRANSMISSION COOLER SUPPLY LINE (METAL TUBING NOT HOSE ELEMENT) DEVELOPED A LEAK DUE TO LONG TERM CONTACT WITH THE ENGINE SUPPORT FRAME CROSSMEMBER. LONG TERM CONTACT RESULTED IN A .25 INCH WIDE X .5 INCH LONG FLAT AREA WORN INTO TUBE WALL WITH A PIN HOLE SIZE PENETRATION THRU THE TUBE WALL. FLUID PRESSURE INSIDE THE TUBE IN COMBINATION WITH THE PIN HOLE SIZE PENETRATION RESULTED IN A SPRAYING LEAK FROM THE TUBE WHICH COATED THE UNDERCARRIAGE OF THE TRUCK AND THE TRAILER THAT WAS IN TOW AT THE TIME OF FAILURE. THE BRAKING SURFACES ON ALL FOUR WHEELS OF THE TRUCK WERE COATED WITH TRANSMISSION FLUID. THE LOW VOLUMETRIC FLOWRATE OF THE LEAK ALLOWED FOR CONTINUED OPERATION OF THE VEHICLE FOR SEVERAL HOURS (AT NIGHT ON FAIRLY LEVEL TERRAIN) WITHOUT ANY INDICATION OF THE ONGOING LEAKAGE. THIS ALLOWED FOR THE UNDERCARRIAGE OF THE VEHICLE INCLUDING THE BRAKING SURFACES TO BE COATED WITH FLUID. THE LEAKAGE WAS IDENTIFIED WHEN THE TRANSMISSION TEMPERATURE GAUGE INDICATED HOT WHILE TRANSITIONING TETON PASS FROM JACKSON WYOMING. INSPECTION OF THE TUBING INSTALLATION REVEALED THAT THE DIRECT CAUSE OF THE LEAKAGE WAS THE AFORE MENTIONED LONG TERM CONTACT WITH THE ENGINE SUPPORT FRAME CROSSMEMBER. THE ROOT CAUSE OF THE ISSUE IS EITHER DESIGN TOLERANCE FOR THE TUBING INSTALLATION OR INCORRECT INSTALLATION OF THE TUBING AT ORIGINAL ASSEMBLY. THE CLAMPING PROVISION DESIGNED INTO THE TUBING INSTALLATION (ATTACHED TO THE SIDE OF THE ENGINE BLOCK ADJACENT TO THE OIL PAN) IN COMBINATION WITH THE INSUFFICIENT LENGTH OF THE TUBING SECTION CROSSING OVER THE ENGINE SUPPORT FRAME CROSSMEMBER RESULTED IN PRELOADED CONTACT BETWEEN THE TUBE AND THE FORWARD EDGE OF THE CROSSMEMBER. AT THE TIME OF THE FAILURE NO REPLACEMENT PARTS WERE AVAILABLE SO THE DAMAGED SECTION OF THE TUBING WAS REMOVED AND REPLACED WITH HIGH PRESSURE HYDRAULIC HOSE. THE REMOVED SECTION OF TUBING WAS RETAINED AND IS AVAILABLE FOR INSPECTION. THE TRUCK REMAINS IN THE TEMPORARY REPAIRED CONDITION AT THIS TIME. *TR