International Harvester 3800

ON CERTAIN SCHOOL BUSES AND TRUCK MODEL VEHICLES MANUFACTURED BETWEEN FEBRUARY 28, 1999, THROUGH APRIL 5, 2004, THE ANTI-LOCK BRAKE SYSTEM ELECTRONIC CONTROL UNIT (ECU) MAY MISINTERPRET A CORRUPT WHEEL SPEED SIGNAL.

ON CERTAIN SCHOOL AND TRANSIT BUSES BUILT WITH BOSCH ZERO OFFSET PIN SLIDE (ZOPS) HYDRAULIC DISC BRAKES, THE ZOPS HYDRAULIC DISC BRAKES MAY EXPERIENCE CALIPERS STICKING IN THE APPLIED POSITION, WHICH CAN RESULT IN EXCESSIVE OR ABNORMAL HEAT GENERATION AT ONE OR MORE OF THE BRAKES.

VEHICLE DESCRIPTION: SCHOOL/TRANSIT BUSES AND MEDIUM DUTY TRUCKS. THE CASTINGS USED ON THE POWER STEERING PUMPS WERE NOT BUILT TO MATCH THE ENGINEERING DRAWINGS, RESULTING IN A THIN WALL IN THE PUMP CASTING OR A COMPLETE CONNECTION OF TWO PASSAGES THAT ARE SUPPOSED TO BE SEPARATED TO CONTROL FLUID FLOW. THE FLUID FLOW MAY BE REDUCED TO LESS THAN THE MINIMUM REQUIRED FLOW RATE TO PROVIDE FULL POWER ASSIST TO THE BRAKE SYSTEM WITH LOW ENGINE SPEED.

VEHICLE DESCRIPTION: SCHOOL BUSES AND HEAVY DUTY TRUCKS EQUIPPED WITH REAR AXLE ASSEMBLIES PRODUCED BY DANA SPICER. CERTAIN REAR AXLE ASSEMBLIES WERE IMPROPERLY HEAT TREATED WHICH COULD ALLOW PINION BREAKAGE AT THE PINION THREADS.

VEHICLE DESCRIPTION: SCHOOL BUSES EQUIPPED WITH THE INTERNATIONAL I6 ELECTRONIC ENGINE AND AN EXTRA THICK BUS BODY FLOOR. THE ACCELERATOR PEDAL TO FLOOR CLEARANCE IS APPROXIMATELY 1.2 INCHES WITH A STANDARD BUS BODY FLOOR. HOWEVER, SOME CUSTOMERS ORDERED AN ADDITIONAL 3/4 INCH THICK FLOOR AND EXTRA THICK FLOOR MATS TO SERVE AS INSULATION IN COLD CLIMATES. WHEN THIS EXTRA FLOORING IS USED, THE BOTTOM EDGE OF THE ACCELERATOR PEDAL, WHEN DEPRESSED, CAN COME IN CONTACT WITH THE FLOOR.

THESE BUSES HAVE A TURN SIGNAL LEVER THAT WILL NOT OPERATE CONSISTENTLY IN THE LANE CHANGE MODE IF THE LEVER IS NOT MOVED TO THE POSITION WHERE RESISTANCE TO MOVEMENT IS FELT.

THE WIRING FROM THE ELECTRONIC CONTROL UNIT WAS CONNECTED TO THE WRONG WHEEL SENSOR OR TO THE WRONG BRAKE MODULATOR VALVE. IT IS POSSIBLE THAT EITHER OR BOTH WIRING MAY HAVE OCCURRED AT EITHER THE FRONT OR REAR AXLE OR BOTH AXLES.

THE AXLE HOUSINGS WERE MANUFACTURED WITH A TIGHT FRICTION WELD CURL RADIUS ON THE INSIDE DIAMETER OF THE AXLE HOUSING. UNDER OPERATIONAL LOADS, CRACKS CAN INITIATE AT THE WELD CURL RADIUS ON THE INSIDE OF THE HOUSING. THESE CRACKS MAY PROPAGATE, EVENTUALLY ALLOWING THE AXLE SPINDLE TO SEPARATE FROM THE AXLE HOUSING.

THE FRONT WHEEL HUB CAN DEVELOP CRACKS AT THE WHEEL MOUNTING STUDS. WHEN MOUNTED TO THE HUB, THE HYDRAULIC BRAKE DISC ROTOR DOES NOT PROPERLY SUPPORT THE HUB AT THE WHEEL STUDS CAUSING EXCESSIVE STRESS AND FATIGUE CRACKS IN THE HUB.

THE WIRE END OF THE HAND THROTTLE CABLE PASSES THROUGH A SPLIT PLASTIC GROMMET IN THE ACCELERATOR ROD. THIS WIRE CAN WORK THROUGH THE SLOT IN THE GROMMET AND BECOME LODGED BETWEEN THE GROMMET AND THE EDGE OF THE HOLE IN THE ACCELERATOR ROD.

FOUR COMPRESSION BACKPLATE RETAINING FASTENERS ON THE TURBO-CHARGER WERE TORQUED ONLY HAND TIGHT. THIS ALLOWS THE FASTENERS TO LOOSEN, AND CAUSES OIL TO LEAK INTO THE COMPRESSOR AIR SIDE OF THE TURBO-CHARGER WHICH, WHEN COUPLED WITH THE HEAT PRECIPITATED BY THE COMPRESSOR AND THE MIXING ACTION OF THE COMPRESSOR WHEEL, CAN RESULT IN AN AIR/OIL MIXTURE THAT FUELS THE ENGINE.

THESE BUSES WERE BUILT WITH AN ADDITIONAL 3/4 INCH THICK PLYWOOD FLOOR AND EXTRA THICK FLOOR MATS FOR INCREASED INSULATION DURING COLD WEATHER. THE BOTTOM EDGE OF THE ACCELERATOR PEDAL, WHEN DEPRESSED, CAN COME IN CONTACT WITH THE HEAD OF A BOLT SECURING THE TRANSMISSION COVER TO THE FLOOR. THE ENGINE THROTTLE MAY NOT RETURN TO THE IDLE POSITION.