Engine Mechanical 3.1l v6 - VIN [M] Chevrolet Lumina I

ENGINE IDENTIFICATION

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

Vehicle Identification Number (VIN)

VIN is stamped on a metal tab, which is attached to top left end of instrument panel, near windshield. If eighth character of VIN is "M", vehicle is factory-equipped with a 3.1L V6 SFI engine. If tenth character of VIN is "S", vehicle is a 1995 model year.

Engine Code & Partial VIN

An engine code (3 characters) and a partial VIN (9 characters) are stamped on cylinder block, in one of the following places.

1. Top of cylinder block, above front cover.
2. On cylinder block flange, where engine mates to transaxle (may be on either side of engine).

Engine code L82 identifies 3.1L V6 SFI engine. If second character of partial VIN is "S", engine is a 1995 model year.

VALVE CLEARANCE (LASH) ADJUSTMENT

Note. This procedure has been revised due to TSB 57-61-35, dated 12/1995. See ROLLER ROCKER ARMS VS BALL & PIVOT ROCKER ARMS .

For 1995, approximately 4000 vehicles were built with roller rocker arms. All other 1995 engines were built with conventional ball and pivot type rocker arms. For 1996, the 3.1L V6 VIN "M" engine can be manufactured with either roller rocker arms or ball and pivot type rocker arms. DO NOT mix rocker arm types on the same engine. It will be necessary to determine which type of rocker arm design the engine was manufactured with when servicing the cylinder head valve train components.

Roller type rocker arms are mounted to cylinder head by non-adjustable pedestals and bolts. Although valve lash is not adjustable, if cylinder head has been resurfaced or valves and seats reground, rocker arm pedestals may be shimmed to compensate.

Conventional ball and pivot type rocker arms are mounted to cylinder head using a stud and nut. Valve lash is not adjustable.

If engine is equipped with replacement rocker arm studs that allow for valve lash adjustment (because valves and seats were reconditioned), adjust valve lash. Remove valve covers. Rotate crankshaft until cylinder No. 1 is at TDC of compression stroke. Begin by adjusting exhaust valve of cylinder No. 1. See VALVE CLEARANCE ADJUSTMENT SEQUENCE table. While trying to rotate push rod with thumb and forefinger, loosen nut on rocker stud until push rod just starts to rotate. This is considered zero lash. Tighten nut an additional 1 1/2 turns (this centers the lifter plunger).

VALVE CLEARANCE ADJUSTMENT SEQUENCE

TROUBLE SHOOTING

Note. To trouble shoot engine mechanical components, see appropriate table in TROUBLE SHOOTING article in GENERAL INFORMATION.

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 negative battery cable. Loosen fuel tank filler cap. Connect Fuel Pressure Gauge (J-34730-1) to fuel line fitting (wrap shop towel around fitting to absorb leakage). Place gauge bleed hose into container. Open bleed valve to release pressure.

COOLING SYSTEM BLEEDING

Open air bleed valve on thermostat housing. Fill radiator until coolant level is even with filler neck and no air bubbles are coming out of air bleed valve. Close air bleed valve. Install radiator cap. Fill coolant reservoir. Warm engine. Allow engine to cool. Fill radiator and coolant reservoir.

Removal & Installation ("W" Body)

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__fuel-pressure-release) . Remove hood. Drain cooling system. Remove air cleaner and ducts. Remove transaxle fluid fill tube. Remove engine mount struts between left side of engine and top of radiator panel.
2. Raise and support vehicle. Drain engine oil. Remove heat shield from exhaust crossover pipe. Disconnect exhaust downpipe from crossover pipe. Remove lower rear bolt securing transaxle to engine. Disconnect control cables, coolant hoses, electrical connectors, vacuum hoses, and fuel lines as necessary.
3. Remove nuts securing mount at timing chain end of engine to bottom of frame. Remove flexplate/flywheel cover. Remove starter. Remove torque converter bolts (A/T). Remove transaxle mount. Lower vehicle. Remove coolant reservoir. Remove serpentine drive belt.
4. Remove plastic cover from strut tower. Remove alternator brackets and alternator. Remove power steering pump pulley. Remove power steering pump and A/C compressor (leave hoses connected). Remove vacuum modulator pipe assembly (A/T). Remove remaining bolts securing transaxle to engine.
5. Install a safety bolt between alternator bracket and engine lift bracket. Support transaxle from below. Attach engine hoist. Remove engine. To install, reverse removal procedure. Fill and bleed cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__cooling-system-bleeding) .

Removal

1. Disconnect negative battery cable. Remove air cleaner and duct assembly. Disconnect control cables and cable bracket from throttle body. Disconnect coolant (thermostat) by-pass pipe from its retainer on upper intake manifold. Disconnect vacuum modulator pipe (A/T).
2. Disconnect power brake booster hose from manifold. Remove engine mount struts between top of radiator panel and left side of engine so engine can be rotated forward to access ignition coil pack. Rotate engine forward. Remove ignition coil pack. Remove alternator brackets. Disconnect vacuum lines and electrical connectors as necessary.
3. Remove MAP sensor. Remove EGR valve. Remove bolts securing upper intake manifold to lower intake manifold. (Scheme 23) Remove upper intake manifold and throttle body as an assembly.

Installation

Clean all gasket surfaces. Install NEW gaskets onto the cylinder heads. Ensure all holes are aligned. For correct installation, observe reference marks on gaskets (if present). Install the upper intake manifold. (Scheme 23) Using a crisscross pattern, tighten bolts to specification. Refer to TORQUE SPECIFICATIONS. To complete installation, reverse removal procedure. Fill and bleed the cooling system if it was drained. Refer to COOLING SYSTEM BLEEDING.

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__fuel-pressure-release). Drain cooling system. Remove coolant reservoir. Remove serpentine drive belt. Remove upper intake manifold. See «INTAKE MANIFOLD (UPPER)»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m). Disconnect fuel lines. Remove fuel rail. Remove power steering pump pulley. Remove power steering pump (leave hoses connected).
2. Disconnect coolant hoses as necessary. Remove rocker arm covers. Remove bolts securing lower intake manifold to cylinder heads. (Scheme 23) Remove lower intake manifold. If necessary, loosen rocker arms and remove push rods to remove gaskets.

1. Clean gasket surfaces. Apply a 7/32" (5-6 mm) bead of RTV sealant to front and rear ridges of cylinder block sealing surfaces. (Scheme 23) Install NEW gaskets onto cylinder heads. Ensure all holes are aligned. For correct installation, observe reference marks on gaskets (if present).
2. Intake push rods (marked Orange ) are shorter than the exhaust push rods (marked Blue ). Install push rods and rocker arms in original locations. If vehicle is equipped with rocker arm studs that allow for adjustment of valve lash, adjust valve lash. Refer to the «VALVE CLEARANCE (LASH) ADJUSTMENT»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__valve-clearance-lash-adjustment) procedures under ADJUSTMENTS.
3. In any case, install lower intake manifold. Using a crisscross pattern, tighten lower intake manifold vertical bolts to specification, then tighten lower intake manifold diagonal bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__torque-specifications). To complete installation, reverse removal procedure. Fill and bleed the cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__cooling-system-bleeding).

Scheme 23

1. Remove air cleaner assembly and duct. Drain cooling system. Remove engine mount struts between top of radiator panel and left side of engine. Rotate engine rearward to access manifold. Remove coolant reservoir. Remove serpentine drive belt. Disconnect upper and lower radiator hoses from engine.
2. Remove vacuum modulator pipe assembly (A/T). Remove heater pipe. Remove heat shield and exhaust crossover pipe. Remove engine mount strut bracket. Remove heat shield, exhaust manifold and gasket.

Reverse removal procedure using NEW gasket. Tighten exhaust manifold fasteners to specification. See TORQUE SPECIFICATIONS . Fill and bleed cooling system. See COOLING SYSTEM BLEEDING .

1. Remove air cleaner assembly and duct. Drain cooling system. Remove engine mount struts between top of radiator panel and left side of engine so engine can be rotated forward to access manifold. Disconnect upper radiator hose from engine. Remove vacuum modulator pipe assembly (A/T). Remove heater pipe.
2. Remove heat shield and exhaust crossover pipe. Remove oxygen sensor. Rotate engine forward to access manifold. Raise and support vehicle. Put an adjustable floor stand under rear crossmember of engine cradle (drivetrain and front suspension frame assembly). Remove bolts, then lower rear crossmember of engine cradle for clearance.
3. Disconnect exhaust downpipe. Disconnect EGR tube. Remove oxygen sensor. Remove transaxle oil fill tube (A/T). Remove heat shield, nuts, exhaust manifold and gasket.

Reverse removal procedure using NEW gasket. Tighten exhaust manifold fasteners to specification. See TORQUE SPECIFICATIONS . Fill and bleed cooling system. See COOLING SYSTEM BLEEDING .

Removal (Left)

1. Release fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__fuel-pressure-release) . Drain the cooling system. Remove the lower intake manifold. Refer to «INTAKE MANIFOLD (LOWER)»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) . Remove exhaust crossover pipe.
2. Remove rocker arm covers. Remove rocker arm bolts or nuts, rocker arms, and push rods. Remove oil dipstick tube. Remove cylinder head bolts, cylinder head and gasket.

Removal (Right)

Release fuel system pressure. See FUEL PRESSURE RELEASE . Drain the cooling system. Remove the lower intake manifold. Refer to INTAKE MANIFOLD (LOWER) . Remove exhaust crossover pipe. Remove rocker arm covers. Remove rocker arm bolts or nuts, rocker arms, and push rods. Remove cylinder head bolts, cylinder head and gasket.

Inspection (Left & Right)

If warpage of cylinder head gasket surface exceeds specification, machine surface. See CYLINDER HEAD table under ENGINE SPECIFICATIONS. DO NOT remove more than .010" (.25 mm) of material from original surface.

Installation (Left & Right)

1. Clean cylinder head bolt threads and cylinder block holes. Install gasket on cylinder block with THIS SIDE UP mark up (if equipped). Ensure all holes align with cylinder block. Install cylinder head. Apply GM Sealant (1052080) to head bolt threads.
2. Tighten cylinder head bolts to specification in sequence. See the «TORQUE SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__torque-specifications). To complete installation, reverse removal procedure. (Scheme 24) Fill and bleed the cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__cooling-system-bleeding).

Scheme 24

1. Drain cooling system. Remove serpentine drive belt. Remove hood panel assembly. Remove engine mount strut, A/C compressor (with hoses attached), and bracket. Remove radiator fan assemblies. Support engine from above with Engine Support Fixture (J-28467) and Adapter Leg (J-36462).
2. Raise and support vehicle. Remove front exhaust pipe. Disconnect intermediate steering shaft from steering gear. Drain crankcase. Remove engine splash shield. Remove bolt and washer securing crankshaft balancer. Use a puller to remove crankshaft balancer.
3. Support engine cradle (drivetrain and front suspension frame assembly) from below with adjustable floor stands. Remove nuts and bolt as necessary, then lower engine cradle away from vehicle. Remove engine mount assembly. Remove flexplate/flywheel cover. Remove starter.
4. Disconnect transaxle mount assembly from oil pan. Remove oil pan. See OIL PAN. Raise engine cradle into position, and install bolts and nuts. Lower vehicle. Remove coolant reservoir. Remove serpentine drive belt.
5. Remove power steering pump pulley. Remove power steering pump (leave hoses connected). Disconnect thermostat by-pass pipe from its retainer on upper intake manifold. Disconnect thermostat by-pass pipe from water pump. Remove water pump pulley.
6. Disconnect radiator hose from water pump. Remove serpentine drive belt tensioner. Remove crankshaft position sensor. Remove bolts, front cover, and gasket. Remove water pump from front cover.

1. Apply RTV sealant to sealing surface of front cover. Install NEW front cover oil seal. See «FRONT COVER OIL SEAL»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) . Apply RTV sealant to keyway in crankshaft and crankshaft damper.
2. Install crankshaft damper using Damper Installer (J-29113). Ensure damper installer threads are at least .20" (5.1 mm) into crankshaft. To complete installation, reverse removal procedure.

Remove serpentine drive belt. Raise and support vehicle. Remove right front wheel and inner fender splash shield. Remove flexplate/flywheel cover. Prevent crankshaft from turning, and remove crankshaft balancer bolt. Remove crankshaft balancer with a puller. Remove crankshaft balancer key. Pry seal out of front cover with a large screwdriver.

Lubricate seal with engine oil. Using Seal Installer (J-35468), install seal with open end toward engine. To complete installation, reverse removal procedure.

TIMING CHAIN & SPROCKETS

Note. If camshaft sprocket does not come off easily, lightly strike lower edge of sprocket with a plastic mallet.

1. Remove the engine front cover. See «FRONT COVER»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m).
2. Rotate the crankshaft until the timing marks in the following locations are aligned: The crankshaft sprocket. The camshaft sprocket locator hole. The engine block The timing chain dampener. The number 1 piston is at dead center.
3. Remove the camshaft sprocket bolt. Remove the camshaft sprocket. (Scheme 25) Remove the timing chain.
4. Use the Crankshaft Sprocket Remover (J 5825-A) in order to remove the crankshaft sprocket. (Scheme 26) Remove the timing chain dampener bolts and the timing chain dampener. (Scheme 27)

Scheme 25

Scheme 26

Scheme 27

Note. Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

1. Install the crankshaft sprocket using the Crankshaft Sprocket Installer (J 38612). (Scheme 28) Apply GM EOS (P/N 1052367) to the sprocket thrust surface.
2. Install the timing chain dampener to the block. (Scheme 27) Tighten the timing chain dampener bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__torque-specifications).
3. Align the crankshaft timing mark to the timing mark on the bottom of the chain dampener. (Scheme 29) Hold the camshaft sprocket with the chain hanging down and install the chain to the crankshaft gear.
4. Align the timing mark on the camshaft gear (center line of the locator hole) with the timing mark on the top of the chain damper. (Scheme 29) Remove the Crankshaft Sprocket Installer (J 38612). Align the dowel in the camshaft with the dowel hole in the camshaft sprocket.
5. Draw the camshaft sprocket onto the camshaft using the mounting bolt. Coat the crankshaft and camshaft sprocket with engine oil.
6. Install the camshaft sprocket bolt. Tighten the camshaft sprocket bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__torque-specifications).
7. To complete installation, reverse removal procedure. Tighten all fasteners to specification.

Scheme 28

Scheme 29

Remove lower intake manifold. See INTAKE MANIFOLD (LOWER) . Remove rocker arms and push rods. Remove bolts and lifter guide. Remove lifters. Mark component locations for installation reference.

If installing old lifters, lubricate lifters and bores with engine oil. If replacing lifters, lubricate the lifter and bores with Prelube (1052365). Install lifters. To complete installation, reverse removal procedure. Tighten nuts and bolts to specification. See the TORQUE SPECIFICATIONS .

1. Remove engine. See «ENGINE»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) . Remove lower intake manifold. See «INTAKE MANIFOLD (LOWER)»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) . Remove rocker arms and push rods. Remove bolts and lifter guide. Remove lifters. Mark component locations for installation reference. Remove front cover. See «FRONT COVER»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) .
2. Remove the timing chain and camshaft sprocket. Refer to «TIMING CHAIN»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__timing-chain-sprockets) . Remove oil pump drive assembly from top rear of cylinder block (held in place with a bolt and clamp like a distributor). Remove camshaft thrust plate. Remove camshaft. If necessary, remove camshaft bearings using Remover/Installer (J-33049).

Inspection

If journal runout, lobe lift or oil clearance is not within specification, replace camshaft. See CAMSHAFT table under ENGINE SPECIFICATIONS.

Lubricate camshaft bearings and lobes with engine oil. Install camshaft. To complete installation, reverse removal procedure. Ensure timing marks are aligned. (Scheme 29) Tighten nuts and bolts to specification. See TORQUE SPECIFICATIONS.

1. Remove transmission. See TRANSMISSION REMOVAL & INSTALLATION article in TRANSMISSION SERVICING (A/T models) or appropriate article in CLUTCHES (M/T models).
2. On M/T models, mark clutch pressure plate and flywheel for installation reference. Remove pressure plate, clutch disc and flywheel. On A/T models, remove flexplate and retainer.
3. On all models, careful pry seal from housing (DO NOT damage sealing surfaces). Note direction of seal installation.

1. Coat inner and outer seal surfaces with engine oil. Install seal on mandrel of Seal Installer (J-34686) until dust lip bottoms against seal installer collar. (Scheme 30)
2. Install seal installer onto crankshaft, aligning dowel pin on seal installer with alignment hole in crankshaft flange. To install seal in seal bore, tighten seal installer handle until collar on seal installer is even with cylinder block.
3. To complete installation, reverse removal procedure. Align reference marks on pressure plate and flywheel (M/T models). Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__torque-specifications).

Scheme 30

Disconnect negative battery cable. Drain cooling system. Remove air cleaner (if necessary). Loosen water pump pulley bolts. Remove serpentine drive belt. Remove water pump pulley bolts and pulley. Note position of locator tab on top of water pump for installation reference. Remove bolts, water pump and gasket.

Apply thread sealant to the water pump bolts. Install water pump and NEW gasket. Ensure the locator tab on top of water pump housing is positioned vertically. Tighten bolts to specification. See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure. Fill and bleed cooling system. See COOLING SYSTEM BLEEDING .

1. Remove hood. Remove engine mount strut, A/C compressor (leave hoses attached), and bracket. Remove radiator fan assemblies. Support engine from above with Engine Support Fixture (J-28467) and Adapter Leg (J-36462). Raise and support vehicle.
2. Remove exhaust crossover pipe. Disconnect intermediate steering shaft from steering gear. Drain crankcase. Remove engine splash shield. Support engine cradle (drivetrain and front suspension frame assembly) with floor stands. Remove nuts securing transaxle mount to left side of frame assembly. From below engine, remove nuts securing engine mount to front crossmember portion of frame assembly.
3. Remove bolts securing frame assembly to body. Lower frame assembly and control arms as an assembly. Remove engine mount assembly below engine. Remove flexplate/flywheel cover. Remove starter. Remove transaxle mount from oil pan. Remove oil pan side bolts, oil pan bottom bolts, and oil pan.

Clean gasket surfaces of oil pan and cylinder block. Apply RTV sealant to tab grooves in rear main bearing. Install oil pan and NEW gasket. Tighten oil pan bottom bolts to specification, then tighten oil pan side bolts. See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure. Fill crankcase.

Gasket Surface

If warpage of gasket surface exceeds specification, machine cylinder head. See CYLINDER HEAD table under ENGINE SPECIFICATIONS. DO NOT remove more than .010" (.25 mm) of material from original surface of cylinder head.

Valve Springs

Replace spring if free length, out-of-square, pressure or installed height is not as specified. See VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS.

Valve Stem Oil Seals

If oversize valves are installed, use oversize seals. Ensure seal is fully seated on guide. Intake and exhaust seals are different.

Valve Guides

If valve stem-to-guide oil clearance is not within specification, ream valve guide and install oversize valve. See CYLINDER HEAD table under ENGINE SPECIFICATIONS. DO NOT knurl valve guides.

Valve Seats

If valve seat width or runout is not within specification, machine or replace valve seat as necessary. See CYLINDER HEAD table under ENGINE SPECIFICATIONS. Valve seat replacement procedure is not available from manufacturer.

Valves

If valve margin is not within specification, replace valve. See VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS.

Valve Seat Correction Angles

If seat contact is too low (too close to stem) or too wide, use a 70-degree stone to raise or narrow seat.

CYLINDER BLOCK ASSEMBLY

Piston & Rod Assembly

Mark piston with cylinder number for installation in original location. Replace rod if bend or twist exceeds specification. See CONNECTING RODS table under ENGINE SPECIFICATIONS. Install piston with arrow on top of piston toward front of engine.

Fitting Pistons

1. Measure cylinder bore diameter at top and center of bore. Measure piston diameter at 90-degree angle to piston pin bore, 1/4" below center line of piston pin bore.
2. If piston clearance is not within specification, machine cylinder bore and install oversize piston(s) as necessary. See «PISTONS, PINS & RINGS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) table under ENGINE SPECIFICATIONS. DO NOT machine oversize piston to fit cylinder bore, or engine balance will be affected.

Piston Rings

If piston ring end gap or side clearance is not within specification, replace piston rings and/or piston as necessary. See PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS. Install piston rings with identification mark on ring land facing top of piston. Properly position end gaps of piston rings around circumference of piston. (Scheme 31)

Rod Bearings

If the connecting rod bearing oil clearance is not within specification, machine crankshaft and replace bearings. Refer to the CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS.

Crankshaft & Main Bearings

Measure the crankshaft main bearing for proper oil clearance, out-of-round and taper. If any measurements are not within specification, machine the crankshaft and replace the bearings. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS.

Thrust Bearing

Measure crankshaft end play (thrust bearing clearance). See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS. If not within specification, replace bearing and/or repair or replace crankshaft.

Cylinder Block Deck Surface

If deck surface warpage exceeds specification, machine surface. DO NOT remove more than .010" (.25 mm) of material from original deck surface.

Valve Lifter Bores

Oversize valve lifters are available. If oversize lifters are installed, stamp oversize on cylinder block near lifter bore to indicate oversize lifters have been installed.

Scheme 31

ENGINE OILING SYSTEM

A camshaft-driven, gear-type oil pump provides pressurized lubrication through oil filter to main gallery above left side of camshaft center line. (Scheme 32) This gallery provides lubrication to valve lifters on left bank, camshaft bearings, crankshaft and right gallery.

Right gallery supplies oil to valve lifters on right bank. Rocker arms are lubricated by passages in push rods. Slot in front camshaft bearing provides lubrication to camshaft sprocket thrust face. Pressure regulator valve is mounted in oil pump body.

Crankcase Capacity

Engine oil capacity is about 4 qts. (3.8L) without filter change. More oil may be necessary when replacing oil filter.

Oil Pressure

Minimum allowable oil pressure is 15 psi (1 kg/cm 2 ) at 1100 RPM.

Scheme 32

Removal & Disassembly

1. Remove oil pan. See «OIL PAN»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) under REMOVAL & INSTALLATION. Remove oil pump bolt, oil pump and extension shaft from rear main bearing cap.
2. To disassemble, remove pump cover. DO NOT remove pick-up tube from cover unless loose or broken. If pick-up tube is loose, bent or has been removed, replace pick-up tube and pump cover. WARNING: On some models, pressure regulator valve spring is under pressure. To prevent personal injury, use care when removing cotter pin.
3. Remove gears from pump body. Remove cotter pin securing spring and pressure regulator valve. Remove valve and spring.

1. Inspect components for damage. Using straightedge and feeler gauge, measure gear end clearance. Measure housing pocket depth and diameter. Measure gear diameter and length (thickness). Measure side clearance between gear tooth and housing.
2. Measure gear lash clearance between gear teeth. Check clearance between pressure regulator valve and bore. Replace components or entire assembly if not within specification. Refer to the «OIL PUMP SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m) table.

OIL PUMP SPECIFICATIONS

Note. Use only original equipment gaskets for oil pump service, as gasket thickness is critical.

Reassembly & Installation

1. Coat all components with engine oil. To reassemble, reverse disassembly procedure using NEW pump cover gasket. If installing new pick-up tube, apply Sealant (1050026) to pick-up tube. Install pick-up tube into pump cover using Suction Pipe Installer (J-21882) and plastic hammer.
2. To install, reverse removal procedure. Ensure pump extension shaft is fully engaged. Tighten oil pump bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/lumina/i-1989-2001/remont/mechanical/#engine-mechanical-31l-v6-vin-m__torque-specifications) .

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

ENGINE SPECIFICATIONS

GENERAL SPECIFICATIONS

CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS

CONNECTING RODS

PISTONS, PINS & RINGS

CYLINDER BLOCK

VALVES & VALVE SPRINGS

CYLINDER HEAD

CAMSHAFT

See also:
• ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
• COMPUTER RELEARN PROCEDURES
• VALVE CLEARANCE ADJUSTMENT SEQUENCE
• FUEL PRESSURE RELEASE
• COOLING SYSTEM BLEEDING
• TORQUE SPECIFICATIONS
• VALVE CLEARANCE (LASH) ADJUSTMENT
• TIMING CHAIN