HT4100 INTAKE MANIFOLD UPDATE RETIGHTENING SEQUENCE

THIS BULLETIN CONTAINS SERVICE INFORMATION COVERING INTAKE MANIFOLD BOLTS AND PARTS USAGE INFORMATION FOR INTAKE MANIFOLD GASKETS. A.LOOSE INTAKE MANIFOLD BOLTS SOME 1982 AND 1983 CADILLACS EQUIPPED WITH HT4100 ENGINES MAY EXHIBIT CONDITIONS OF POOR PERFORMANCE, POOR OIL ECONOMY AND/OR EXCESSIVE COOLANT LOSS. THESE CONDITIONS MAY RESULT FROM LEAKS AT THE INTAKE MANIFOLD TO CYLINDER HEAD SEAL (LOOSE INTAKE MANIFOLD BOLTS). A LOSS OF CLAMP BETWEEN THE INTAKE MANIFOLD AND CYLINDER HEAD(S) MAY OCCUR AS THE INTAKE MANIFOLD GASKET "CRUSHES" AND BECOMES SLIGHTLY THINNER OVER TIME. IF THESE CONDITIONS ARE ENCOUNTERED, INTAKE MANIFOLD BOLT TORQUE SHOULD BE CHECKED. IF ANY BOLTS ARE FOUND TO BE LOOSE, ALL INTAKE BOLTS SHOULD BE RETORQUED ACCORDING TO THE PROCEDURE SHOWN IN FIGURE 1 NOTICE: DO NOT EXCEED 30 N.M (22 FT. LBS.) ON FINAL TORQUE. EXCEEDING THIS FINAL TORQUE SPECIFICATION OR NOT FOLLOWING THE RECOMMENDED TORQUE PROCEDURE COULD CAUSE ENGINE BLOCK DISTORTION AND RESULT IN STRESS TO OTHER ENGINE COMPONENTS (PARTICULARLY TO MAIN BEARINGS). RETORQUING THE MANIFOLD WITH EXISTING GASKETS IN PLACE IS A MORE RELIABLE REPAIR IN MOST CASES THAN INSTALLING NEW GASKETS. NEW GASKETS WILL EXPERIENCE A "CRUSH" SIMILAR TO ORIGINAL GASKETS AND A LOSS OF CLAMP MAY RECUR. B.INTAKE MANIFOLD GASKET KIT THE INTAKE MANIFOLD GASKET KIT (P/N 3634571) IS USED TO SERVICE BOTH 1982 AND 1983 HT4100 ENGINES. THIS KIT CONTAINS THREE INTAKE MANIFOLD GASKETS (2 WITHOUT A RESTRICTOR AND 1 WITH A RESTRICTOR) AND TWO SEALS (1 FRONT AND 1 REAR). FOR 1983 ENGINES, THE AMOUNT OF EFE FLOW TO THE INTAKE MANIFOLD WAS REDUCED BY USING A SPECIFIC RIGHT SIDE GASKET WHICH CONTAINS A RESTRICTOR. THEREFORE, WHEN USING THIS GASKET KIT FOR 1983 ENGINES, THE INTAKE MANIFOLD GASKET WITH THE RESTRICTOR SHOULD BE USE ON THE RIGHT SIDE AND ONE OF THE REMAINING GASKETS (WITHOUT RESTRICTOR) ON THE LEFT SIDE (REFER TO FIGURE 3). FOR 1982 ENGINES, THE GASKET WITH THE RESTRICTOR IS NOT USED (REFER TO FIGURE 3).

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.