7.4L V8 - VIN [N]: Removal & Installation GMC Pickup C2500

Removal & Installation

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(ref-50023-S35614868172001011600000) under REMOVAL & INSTALLATION. Disconnect battery. Remove hood. Drain cooling system.
2. Remove air cleaner, accessory drive belt, fan and water pump pulley. Remove radiator and fan shroud. Disconnect heater hoses from engine. Disconnect fuel lines, electrical connectors, vacuum hoses, coolant hoses and control cables as necessary.
3. Remove A/C compressor and power steering pump with hoses attached and position aside (if equipped). Raise and support vehicle. Drain crankcase. Disconnect exhaust pipes from manifolds. Remove starter. Remove flywheel cover. Remove torque converter bolts (A/T).
4. Remove bellhousing bolts and engine mount through-bolts. Lower vehicle. Support transmission. Attach engine hoist. Remove engine. To install, reverse removal procedure. Fill crankcase and cooling system.

Removal

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(ref-50023-S35614868172001011600000). Disconnect battery. Drain cooling system. Remove air cleaner.
2. Disconnect fuel lines, electrical connectors, vacuum hoses, coolant hoses and control cables as necessary. Remove alternator bracket, A/C compressor (with hoses attached), injection unit and cruise control servo as necessary.
3. Remove distributor cap. Mark distributor rotor in relation to distributor housing. Mark base of distributor housing in relation to intake manifold. Remove distributor. DO NOT rotate crankshaft while engine is apart. Remove intake manifold bolts, intake manifold and gaskets. (Scheme 56)

Installation

1. Install front and rear intake manifold seals on cylinder block. (Scheme 56) Install gaskets on cylinder heads.
2. Install intake manifold and bolts. Tighten bolts in sequence to specification. (Scheme 57) See «TORQUE SPECIFICATIONS»(ref-50023-S20255966672001011600000). To complete installation, reverse removal procedure. Fill cooling system. Set ignition timing to specification. See «IGNITION TIMING (GASOLINE)»(ref-10385-S25389368312001010200000) in ON-VEHICLE ADJUSTMENTS article in ENGINE PERFORMANCE.

Scheme 56

Scheme 57

Remove heat stove tube. Remove all attached brackets and heat shields. If necessary, remove dip stick tube. Disconnect oxygen sensor electrical connector. Disconnect exhaust pipe from manifold. Remove exhaust manifold bolts and exhaust manifold.

Install manifold. Tighten bolts to specification. See TORQUE SPECIFICATIONS table. Bend lock tabs (if equipped). To complete installation, reverse removal procedure.

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(ref-50023-S35614868172001011600000) under REMOVAL & INSTALLATION. Remove intake manifold. See «INTAKE MANIFOLD»(ref-50023-S05008992612001011600000) under REMOVAL & INSTALLATION.
2. Remove exhaust manifold. See «EXHAUST MANIFOLD»(ref-50023-S29422158432001011600000) under REMOVAL & INSTALLATION. Remove valve covers. Loosen rocker arm nuts. Rotate rocker arms aside. Remove push rods and mark for reassembly to original locations. Remove cylinder head bolts. Remove cylinder head.

1. Clean gasket surfaces, bolt threads and bolt holes. If using steel head gasket, thinly coat both sides of gasket with sealant. DO NOT apply sealant to composition (steel/asbestos) head gaskets. Position head gasket on cylinder block. Ensure all holes align. Coat head bolt threads with GM Sealant (1052080).
2. Install cylinder head with bolts finger-tight. Tighten head bolts in sequence to specification. (Scheme 58) See «TORQUE SPECIFICATIONS»(ref-50023-S20255966672001011600000). Lubricate valve tip, rocker arm pivot and push rod socket with Molykote.
3. To complete installation, reverse removal procedure. Adjust valves. See «VALVE CLEARANCE ADJUSTMENT»(ref-50023-S33148611422001011600000) under ADJUSTMENTS.

Scheme 58

Remove accessory drive belt(s) and pulley. Remove crankshaft damper bolt. Using Damper Puller/Installer (J-39046), remove crankshaft damper. Carefully pry seal from cover with screwdriver. DO NOT distort front cover.

1. Coat seal lip with engine oil. Using Seal Installer (J-22102), install new seal in front cover with seal lip facing engine. Apply RTV sealant to Woodruff keyway in crankshaft damper.
2. Using Damper Puller/Installer (J-39046), install crankshaft damper. Install crankshaft damper bolt and tighten to specification. See «TORQUE SPECIFICATIONS»(ref-50023-S24466009852001011600000) table. To install remaining components, reverse removal procedure.

1. Disconnect battery. Drain cooling system. If necessary, remove radiator shroud. Remove accessory drive belts, fan and pulley. Remove crankshaft damper bolt. Using Damper Puller/Installer (J-39046), remove crankshaft damper.
2. Remove all mounting brackets and coolant hoses attached to water pump. Remove water pump. Loosen or remove oil pan as necessary for removal of front cover. Remove front cover bolts, front cover and gasket.
3. Rotate crankshaft until timing marks on camshaft and crankshaft sprockets are aligned. (Scheme 59) Remove camshaft sprocket and timing chain. To remove crankshaft sprocket, use Sprocket Puller (J-1619).

1. Install Woodruff key in crankshaft (if removed). Using Crankshaft Sprocket Installer (J-22102), install crankshaft sprocket. Install the camshaft sprocket and the timing chain, ensuring the timing marks on the sprockets are aligned. (Scheme 59)
2. Install and tighten camshaft sprocket bolts to specification. See «TORQUE SPECIFICATIONS»(ref-50023-S24466009852001011600000) table. Install gasket to front cover with gasket sealant. Install front cover and gasket.
3. Apply RTV sealant to Woodruff keyway in crankshaft damper. Using Damper Puller/Installer (J-39046), install crankshaft damper. Install crankshaft damper bolt and tighten to specification. See «TORQUE SPECIFICATIONS»(ref-50023-S24466009852001011600000) table. To install remaining components, reverse removal procedure.

Scheme 59

Remove transmission, clutch (M/T) and flywheel. Using screwdriver, pry seal from housing. DO NOT scratch crankshaft sealing surface. Note direction of seal lip.

1. Lubricate inner and outer diameter of seal with engine oil. Place seal on Seal Installer (J-38841). Position seal installer against crankshaft.
2. Thread attaching screws into crankshaft flange and tighten with screwdriver. This squares seal with crankshaft. Rotate seal installer handle until it bottoms. Remove seal installer. Install flywheel, clutch (M/T) and transmission.

Disconnect battery. Drain cooling system. Remove all drive belts, coolant hoses and mounting brackets attached to water pump. If necessary, remove fan shroud. Remove fan and pulley. Remove water pump and gaskets.

Install water pump with new gaskets. Tighten water pump bolts to specification. See TORQUE SPECIFICATIONS table. To install remaining components, reverse removal procedure.

1. Disconnect battery. Remove fan shroud bolts. Move shroud rearward. Remove air cleaner and distributor cap. Raise and support vehicle. Drain crankcase. Remove starter (M/T). Remove flywheel cover and oil filter.
2. Disconnect oil pressure line from side of cylinder block. Remove front engine mount through-bolts. Raise and support engine. Remove oil pan bolts, oil pan and gasket.

1. Apply RTV sealant to both sides of oil pan gasket.
2. Install oil pan. Tighten oil pan bolts to specification. See «TORQUE SPECIFICATIONS»(ref-50023-S24466009852001011600000) table. To install remaining components, reverse removal procedure. Fill crankcase.

1. Remove intake manifold. See «INTAKE MANIFOLD»(ref-50023-S05008992612001011600000) under REMOVAL & INSTALLATION. Remove valve covers. Loosen all rocker arm nuts and rotate rockers aside.
2. Remove push rods, noting location for reassembly reference. Remove lifters, noting location for reassembly reference.

Coat lifter feet and body with High Viscosity Oil/Zinc (12345501). Install lifters in original location. To install remaining components, reverse removal procedure.

Remove radiator, Discharge A/C system (if equipped) using approved refrigerant recovery/recycling equipment and remove A/C condenser (if equipped) and grille. Remove valve lifters. See VALVE LIFTERS under REMOVAL & INSTALLATION. Remove timing chain and camshaft sprocket. See TIMING CHAIN & SPROCKETS under REMOVAL & INSTALLATION. If necessary, raise engine. Remove camshaft.

Coat camshaft lobes and bearing journals with High Viscosity Oil/Zinc (12345501). Install camshaft. To install remaining components, reverse removal procedure.

Removal & Disassembly

1. Remove oil pan. See «OIL PAN»(ref-50023-S41657864282001011600000) under REMOVAL & INSTALLATION. Remove oil pump bolt. Remove pump and extension shaft.
2. Remove pump cover. Mark relationship between gears at a meshing point for reassembly. Remove gears. Remove pressure regulator valve retaining pin. Remove pressure regulator valve and spring.

Reassembly & Installation

1. Install pump gears into pump body with marked gear teeth indexed. If pick-up tube was removed, apply sealant to tube end. Tap tube end into pump using plastic hammer. Reassemble remaining components in reverse order of disassembly.
2. Prime oil pump with engine oil. Install pump and extension shaft, ensuring slot on top of extension shaft engages with drive tang on end of distributor shaft. Tighten oil pump bolt to specification. See «TORQUE SPECIFICATIONS»(ref-50023-S24466009852001011600000) table. Install oil pan.