5.0L (305") v8 - VIN [H] Chevrolet Forward Control P30

ENGINE IDENTIFICATION

Note. For engine repair procedures not covered in this article, see ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION article in the GENERAL INFORMATION section.

Engine can be identified by eighth character of Vehicle Identification Number (VIN). VIN is stamped on a metal tag on top left end of instrument panel, near windshield. See ENGINE IDENTIFICATION table.

Engine can also be identified by engine identification (ID) number. Number is stamped on front of cylinder block, immediately forward of right cylinder head or on left side of cylinder block, on engine-to-transmission mating flange.

ENGINE IDENTIFICATION CODES

VALVE CLEARANCE ADJUSTMENT

Note. Although valve clearance adjustment is not usually required (engine uses hydraulic valve lifters), perform following procedures after servicing valve train.

1. Rotate engine until No. 1 piston is on TDC of compression stroke. Go next step and adjust specified valves listed in appropriate «VALVE CLEARANCE ADJUSTMENT»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) table.
2. Loosen rocker arm adjusting nut until lash is present. Tighten adjusting nut until lash is removed (under this condition, push rod cannot be rotated with fingers). Tighten adjusting nut one full turn.
3. Rotate crankshaft 360 degrees to bring No. 6 piston to TDC of compression stroke. Adjust remaining valves. See appropriate «VALVE CLEARANCE ADJUSTMENT»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) table

VALVE CLEARANCE ADJUSTMENT

GENERAL PRECAUTION

Note. For reassembly reference, label all electrical connectors, vacuum hoses and fuel lines before removal. Also place mating marks on engine hood and other major assemblies before removal.

FUEL PRESSURE RELEASE

Disconnect battery terminals. Loosen fuel tank cap to relieve tank pressure. Internal constant bleed feature in injection unit relieves fuel system pressure when ignition switch is turned off. No further pressure relief is required.

ENGINE

Note. The engine and transmission are removed as an assembly.

Removal & Installation (Van)

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__fuel-pressure-release) under REMOVAL & INSTALLATION. Disconnect battery negative cable. Drain cooling system.
2. Remove coolant recovery reservoir. Remove grille, lower grille valance and upper radiator support. Discharge A/C system (if equipped) using approved refrigerant recovery/recycling equipment. Remove A/C condenser and radiator. Remove power steering pump with hoses attached and position aside (if equipped).
3. Remove engine cover, air cleaner and injection unit. Disconnect fuel lines, electrical connectors, vacuum hoses, coolant hoses and control cables as necessary. Remove thermostat housing and oil filler tube. Raise and support vehicle. Disconnect exhaust pipes from manifolds.
4. Disconnect drive shaft from transmission. Disconnect transmission shift linkage and vehicle speed sensor connector from transmission. Drain crankcase. Remove transmission mount bolts. Support engine with jack.
5. Remove front engine mounts and place wood blocks between cylinder block and frame. Lower vehicle. Attach engine hoist. Remove engine and transmission as an assembly. To install, reverse removal procedure. Fill crankcase and cooling system. Evacuate and charge A/C system. NOTE: The engine and transmission are removed as an assembly through side door.

Removal & Installation (Commercial Van)

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__fuel-pressure-release) under REMOVAL & INSTALLATION. Disconnect battery. Drain cooling system. Remove engine cover and floor panel sections from inside vehicle.
2. Remove air cleaner, duct and exhaust heat stove pipe. Remove distributor cap and position aside. Disconnect all engine harness electrical connectors and position harness aside. Disconnect fuel lines from injection unit. Remove fuel line clamps from transmission and position fuel lines aside.
3. Disconnect hydraulic line from clutch slave cylinder. Disconnect ground strap from rear end of left cylinder head. Disconnect all transmission harness electrical connectors and position harness aside. Remove transmission shift lever (M/T).
4. Remove upper radiator hose, all accessory drive belts, fan, fan pulley, fan shroud and lower radiator hose. Remove engine oil filler tube. Raise and support vehicle. Disconnect exhaust pipes from manifolds. Disconnect battery cable from clamp on cylinder block.
5. Disconnect drive shaft from transmission. Remove transmission mount. Disconnect oil cooler lines from oil filter adapter. Disconnect oil cooler line clamps from engine. Attach engine hoist.
6. Remove engine mount through-bolts. Remove engine and transmission assembly through side door. To install, reverse removal procedure. Fill crankcase and cooling system.

Removal

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__fuel-pressure-release) under REMOVAL & INSTALLATION. 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. Remove intake manifold bolts, intake manifold and gaskets.

Installation

1. Install gaskets on cylinder heads. Apply a 3/16" (5 mm) bead of RTV silicone sealant to front and rear intake manifold-to-cylinder block mounting surfaces. (Scheme 33) Extend bead 1/2" (13 mm) beyond cylinder block-to-cylinder head junction.
2. Install intake manifold and bolts. Tighten bolts in sequence to specification. (Scheme 34) See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) at end of article. To complete installation, reverse removal procedure. Fill cooling system.

Scheme 33

Scheme 34

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 at end of article. Bend lock tabs (if equipped). To complete installation, reverse removal procedure.

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__fuel-pressure-release) under REMOVAL & INSTALLATION. Remove intake manifold. See «INTAKE MANIFOLD»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) under REMOVAL & INSTALLATION.
2. Remove exhaust manifold. See «EXHAUST MANIFOLD»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) 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 35) See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) at end of article. 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»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__valve-clearance-adjustment) under ADJUSTMENTS.

Scheme 35

Remove accessory drive belt(s) and pulley. Remove crankshaft damper bolt. Using Damper Puller/Installer (J-23523-E), 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-35468), install new seal in front cover with seal lip facing engine. Apply RTV sealant to Woodruff keyway in crankshaft damper.
2. Install crankshaft damper. Install crankshaft damper bolt and tighten to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) at end of article. 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-23523-E), remove crankshaft damper.
2. Remove all mounting brackets and coolant hoses attached to water pump. Remove water pump. Remove oil pan. See «OIL PAN»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__oil-pan) under REMOVAL & INSTALLATION. Remove front cover and gasket.
3. Rotate crankshaft until timing marks on camshaft and crankshaft sprockets are aligned. (Scheme 36) Remove camshaft sprocket and timing chain. To remove crankshaft sprocket, use Sprocket Puller (J-5825-A).

1. Install Woodruff key in crankshaft (if removed). Using Crankshaft Sprocket Installer (J-5590), install crankshaft sprocket. Install the camshaft sprocket and the timing chain, ensuring the timing marks on the sprockets are aligned. (Scheme 36)
2. Install and tighten camshaft sprocket bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) at end of article. Install gasket to front cover with gasket sealant. Install front cover and gasket.
3. Apply RTV sealant to Woodruff keyway in crankshaft damper. Install crankshaft damper. Install crankshaft damper bolt and tighten to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications). To install remaining components, reverse removal procedure.

Scheme 36

ROCKER ARM STUDS

Removal & Installation

1. Rocker arm studs are pressed into cylinder head. Using Stud Remover (J-5802-01), place remover over stud. Install flat washer and nut. Tighten nut to remove stud from cylinder head.
2. If stud is loose in cylinder head, ream stud bore for oversize stud using Reamer (J-5715) for .003" (.08 mm) oversize stud and (J-6036) for .013" (.33 mm) oversize stud.
3. Coat press-fit area of stud with hypoid axle lubricant. Using Stud Driver (J-6880), drive stud into bore until driver bottoms against cylinder head.

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-35621). 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 at end of article. To install remaining components, reverse removal procedure.

OIL PAN

1. Disconnect battery. Raise and support vehicle. Drain crankcase. Remove exhaust crossover pipe, strut rods, strut rod brackets and flywheel cover.
2. Remove starter. Remove or disconnect engine oil cooler lines and/or transmission fluid lines as necessary. Remove oil pan bolts, oil pan and gasket.

1. Apply RTV sealant to front cover-to-cylinder block junction and rear main bearing-to-cylinder block junction.
2. Install oil pan. Tighten oil pan bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) at end of article. To install remaining components, reverse removal procedure. Fill crankcase.

1. Remove intake manifold. See «INTAKE MANIFOLD»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) 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.

Valve Springs

1. Measure valve spring free length, installed height and pressure (tension). Replace valve spring if measurement is not within specification. See «VALVES & VALVE SPRINGS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) table under ENGINE SPECIFICATIONS at end of article.
2. Measure installed height between cylinder head spring seat (or top of shim, if shimmed) and top of spring shield. If installed height exceeds specification, install shims as necessary to bring installed height to specification. Ensure installed height is not less than specified.

Valve Stem Oil Seals

1. Intake and exhaust valves use upper "O" ring seal and lower umbrella seal.
2. When installing umbrella seal, seat seal against valve guide boss on cylinder head. Coat upper "O" ring seal with engine oil before installation and ensure seal is not twisted when installed.

Valve Guides

Valve guides are part of cylinder head (not replaceable). Measure valve guide oil clearance. See CYLINDER HEAD table under ENGINE SPECIFICATIONS at end of article. If not within specification, ream valve guide and install valves with oversize stems.

Valves

Replace valve if margin is less than 1/32" (.8 mm).

Rocker Arm Assembly

Clean push rods, rocker arms, balls and nuts with solvent and blow dry. Inspect rocker arms and balls at mating surface. Surface should be smooth and free of damage. Inspect push rods for bends or wear. Ensure oil passages are clear.

Piston & Rod Assembly

1. Mark piston in relation to cylinder bore before removal. Piston pin is press-fit in connecting rod. Mark piston in relation to connecting rod before separating components.
2. Replace piston and piston pin as matched set. Install piston in bore with notch on top of piston toward front of engine.

Fitting Pistons

1. Measure piston diameter at 90-degree angle to piston pin, on piston pin center line. Measure cylinder bore diameter 2 1/2" below cylinder block deck. Determine piston clearance.
2. If piston clearance is not within specification, replace piston and/or machine cylinder bore as necessary. See CYLINDER BLOCK table and PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS at end of article.

Piston Rings

Measure piston ring end gap and side clearance. If measurement is not within specification, replace piston and/or rings as necessary. See PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS at end of article. Install rings with mark on ring facing upward. Position ring end gaps around circumference of piston as shown. (Scheme 37)

Scheme 37

Rod Bearings

1. Measure rod bearing journal out-of-round, taper and oil clearance. If measurement is not within specification, replace rod bearings and/or machine crankshaft. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS at end of article.
2. Ensure rod side play is within specification. See CONNECTING RODS table under ENGINE SPECIFICATIONS at end of article.

Crankshaft & Main Bearings

1. Mark bearing caps for reassembly. Measure journal diameter, out-of-round, taper and oil clearance. If measurement is not within specification, replace main bearings and/or machine crankshaft. See «CRANKSHAFT»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h) , MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS at end of article.
2. Align thrust bearing surfaces, and measure crankshaft end play. See THRUST BEARING. NOTE: Distance between rear main bearing thrust faces on some engines is .008" (.20 mm) wider than standard. When replacing rear main bearings on these engines (identified by .008" stamped on crankshaft rear counterweight), use only .008"(.20 mm) wider bearings.

Thrust Bearing

1. Install main bearing caps (except rear), and tighten cap bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) at end of article. Install rear main bearing cap and tighten cap bolts to 10 ft. lbs. (14 N.m).
2. Tap crankshaft rearward then forward to align thrust surfaces. Tighten rear main bearing cap bolts to specification. Measure crankshaft end play at forward thrust surface of rear main bearing cap. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS at end of article.

Cylinder Block

Measure cylinder bore out-of-round and taper. If measurement is not within specification, machine cylinder bore and/or replace piston. See CYLINDER BLOCK table under ENGINE SPECIFICATIONS at end of article.

DESCRIPTION

Gear-type oil pump delivers full pressure lubrication through full-flow oil filter to main oil gallery. Main oil gallery feeds crankshaft and camshaft bearings through drilled passages in block.

Valve lifter oil gallery feeds valve lifters. From lifters, oil is routed through hollow push rods to upper valve train components. Timing chain and sprockets are lubricated by oil drainage from No. 1 camshaft bearing. Pistons and piston pins are lubricated by oil splash. Non-adjustable oil pressure regulator is located in oil pump body.

Crankcase Capacity

See CRANKCASE CAPACITY table.

CRANKCASE CAPACITY (1)

Oil Pressure

Measure oil pressure with engine at operating temperature and specified RPM. See OIL PRESSURE SPECIFICATIONS table.

OIL PRESSURE SPECIFICATIONS (1)

OIL PUMP

Note. The pick-up tube is serviceable, however, DO NOT remove tube from pump body unless tube is damaged.

Removal & Disassembly

1. Remove oil pan. See OIL PAN under REMOVAL & INSTALLATION. Remove oil pump bolt. Remove pump and extension shaft. Remove pick-up tube (if necessary).
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.

Inspection

Inspect pump body and cover for cracks or excessive wear. Inspect pump gears for damage or wear. Check drive gear shaft for looseness in pump body. Check pressure regulator valve for fit in bore. Replace entire pump assembly if damaged. Inspect inlet tube and screen assembly for damage.

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»(/chevrolet/forward-control-p30/1985-1999/remont/mechanical/#50l-305-v8-vin-h__torque-specifications) . Install oil pan.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

GENERAL SPECIFICATIONS

CRANK, MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS

CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS

CONNECTING RODS SPECIFICATIONS

CONNECTING RODS

PISTONS, PINS & RINGS SPECIFICATIONS

PISTONS, PINS & RINGS

CYLINDER BLOCK SPECIFICATIONS

CYLINDER BLOCK

VALVES & VALVE SPRINGS SPECIFICATIONS

VALVES & VALVE SPRINGS

CYLINDER HEAD SPECIFICATIONS

CYLINDER HEAD

CAMSHAFT SPECIFICATIONS

CAMSHAFT

See also:
• ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
• ENGINE IDENTIFICATION
• FUEL PRESSURE RELEASE
• TORQUE SPECIFICATIONS
• VALVE CLEARANCE ADJUSTMENT
• OIL PAN