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torque curve while increasing higher rpm horse- If, for some reason, the molded-in vacuum ports break, the composite manifold can be salvaged. The DIAGNOSIS AND TESTING INTAKE MANIFOLD LEAKS An intake manifold air leak is characterized by lower than normal manifold vacuum. Also, one or WARNING: USE EXTREME CAUTION WHEN THE (1) Start the engine. the suspected leak area. (3) If engine RPM’S change, the area of the sus- pected leak has been found. (4) Repair as required. INTAKE MANIFOLD - UPPER STANDARD PROCEDURE STANDARD PROCEDURE - MANIFOLD The composite upper intake manifold thread bosses, if stripped out, can be repaired by utilizing a t parts. Repair screws are available for the following manifold • MAP sensor • Power steering reservoir • EGR tube • Throttle cable bracket The repair screws require a unique tightening torque specification from the original screw. Refer to DESCRIPTION TORQUE* STRIP-OUT REPAIR SCREWS ONLY MAP Sensor Repair 4 N·m (35 in. lbs.) Power Steering Reservoir 9 N·m (80 in. lbs.) EGR Tube Attaching 9 N·m (80 in. lbs.) Throttle Cable Bracket 9 N·m (80 in. lbs.) *Install Slowly Using Hand Tools Only STANDARD PROCEDURE - INTAKE MANIFOLD The composite intake manifold vacuum ports can be repaired. Although, if the manifold plenum cham- To repair a broken or damaged vacuum nipple (port) on the composite intake manifold, perform the PARTS REQUIRED TOOLS REQUIRED · Brass Nipple – 1/4 9 O.D. x 1/8 9 pipe thread (LDP/Speed Control Port) · Pipe Tap – 1/8 9 - 18 NPT · Drill Bit – 11/32 9 · File/Sandpaper · Brass Nipple – 1/2 9 O.D. x 1/4 9 pipe thread (Brake Booster Port) · Pipe Tap – 1/4 9 - 18 NPT · Drill Bit – 7/16 9 · File/Sandpaper NOTE: While performing this procedure, avoid get- (1) File or sand the remaining port back until a flat surface is obtained (plane normal to nipple (port) (2) Drill out the nipple (port) base using a 7/16” (brake booster port) or 11/32” (LDP/speed control port (3) Using a 1/4”–18 NPT (brake booster port) or 1/8”–18 NPT (LDP/speed control port ) pipe tap, cut RS ENGINE 3.3/3.8L 9 - 149 INTAKE MANIFOLD (Continued) |