ENGINE TURBO & HEAD REMOVAL PROCEDURE OUTLINED

CLEARANCE CONDITIONS BETWEEN THE TURBOCHARGER HEAT SHIELDS AND COWL MAY MAKE TURBOCHARGER AND CYLINDER HEAD REMOVAL DIFFICULT. TO REDUCE THE AMOUNT OF TIME REQUIRED TO REMOVE AND REPLACE TURBOCHARGER AND CYLINDER HEAD, THE FOLLOWING TWO PROCEDURES SHOULD BE FOLLOWED WHEN TURBOCHARGER AND RIGHT BANK EXHAUST MANIFOLD TUBE CLAMP ACCESSIBILITY ARE REQUIRED. DURING REINSTALLATION OF HEAT SHIELDS, THE RIGHT BANK HEAT SHIELD SHOULD BE REWORKED AND THE UPPER RIGHT BANK EXHAUST MANIFOLD CLAMP REPOSITIONED TO PROVIDE FUTURE ACCESS. IN ADDITION TO FOLLOWING STEPS OUTLINED IN THE DETROIT DIESEL ALLISON FUEL PINCHER SERVICE MANUAL, SECTIONS 1.2 (CYLINDER HEAD REMOVAL) AND 3.5 (TURBOCHARGER REMOVAL) THE SUGGESTED PROCEDURE SHOULD BE FOLLOWED. TURBOCHARGER HEAT SHIELD REMOVAL 1. REMOVE VEHICLE SHIFT LEVER BOOT, FLOOR MAT, AND CAB FLOOR PANEL LOCATED DIRECTLY ABOVE TRANSMISSION. 2. REMOVE FOUR (4) BOLTS ATTACHING SHIFT TOWER TO TRANSMISSION AND REMOVE SHIFT TOWER. 3. COVER TRANSMISSION OPENING WITH A SHOP TOWEL. 4. REFER TO FIGURE 1 AND REMOVE HEAT SHIELD ATTACHED TO CAB COWL AND FLOOR (FOUR BOLTS) AND REMOVE SHIELD THROUGH FLOOR OPENING. 5. REMOVE EACH UPPER BOLT THAT ATTACHES THE LEFT AND RIGHT EXHAUST MANIFOLD TUBE HEAT SHIELD TO CYLINDER HEAD. 6. DISCONNECT EXHAUST PIPE FROM REAR SIDE OF TURBOCHARGER. 7. REMOVE LEFT AND RIGHT UPPER EXHAUST MANIFOLD TUBE CLAMPS NEXT TO TURBOCHARGER. 8. CONTINUE REMOVING TURBOCHARGER AS OUTLINED IN THE FUEL PINCHER SERVICE MANUAL. 9. FOR REINSTALLATION OF TURBOCHARGER HEAT SHIELDS, FLOOR PANEL, ETC. REVERSE STEPS PREVIOUSLY PERFORMED. THE RIGHT BANK CYLINDER HEAD CAN BE REMOVED MUCH EASIER WHEN THE UPPER EXHAUST MANIFOLD TUBE CLAMP IS REPOSITIONED AND HEAT SHIELD REWORKED AS SHOWN IN FIGURE. THE FOLLOWING PROCEDURE SHOULD BE FOLLOWED WHEN PERFORMING THIS REWORK 1. REMOVE FUEL RETURN LINE LOCATED AT REAR OF RIGHT BANK CYLINDER HEAD AND PLUG OPENINGS. 2. REMOVE RIGHT BANK HEAT SHIELD UPPER ATTACHMENT BOLT. 3. REFER TO FIGURE 2 AND REPOSITION UPPER, RIGHT EXHAUST MANIFOLD TUBE CLAMP. NOTE: TO GAIN ADDITIONAL CLAMP ACCESSIBILITY, IT MAY BE NECESSARY TO REMOVE VEHICLE'S FLOOR PAN AND TURBOCHARGER HEAT SHIELD AS PREVIOUSLY DISCUSSED. 4. USING A PAIR OF TIN SNIPS, CUT A 1 1/2" WIDE SLOT DIRECTLY ABOVE THE UPPER EXHAUST MANIFOLD TUBE CLAMP AS SHOWN IN FIGURE 2. THE SLOT SHOULD BE CUT 1 1/4" LONG AND TAPERED AT AN ANGLE TO PROVIDE A 1/2" WIDE GAP AT REAR OF SLOT. 5. BEND THE METAL UPWARD AND DOWNWARD WITH A PAIR OF PLIERS UNTIL IT BREAKS OFF. 6. FILE SHARP EDGES SURROUNDING THE CUT SLOT. 7. REATTACH HEAT SHIELD TO CYLINDER HEAD. 8. REINSTALL FUEL RETURN LINE. WHEN THE RIGHT BANK EXHAUST MANIFOLD TUBE CLAMP IS CORRECTLY POSITIONED, A DEEP WELL SOCKET CAN BE PLACED BETWEEN THE AIR INTAKE MANIFOLD AND FUEL RETURN LINE FOR CLAMP NUT REMOVAL.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.