2.8l v6 - VIN [r] GMC Sonoma Syclone

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 may be identified by the eighth character of Vehicle Identification Number (VIN) on top of instrument panel, near lower left corner of windshield. Eighth character (R) identifies 2.8L TBI engine.

Engine may also be identified by engine code number stamped on right side of cylinder block below cylinder No. 1 exhaust manifold port, or on front of cylinder block above timing chain cover (to left of center). Engine code number LL2 identifies 2.8L TBI engine.

ENGINE IDENTIFICATION CODES

VALVE CLEARANCE ADJUSTMENT

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

1. Remove rocker arm cover. Rotate crankshaft until cylinder No. 1 is at TDC of compression stroke. Grasp cylinder No. 1 intake valve push rod with thumb and forefinger, and attempt to rotate.
2. Loosen adjusting nut until push rod rotates freely. Continue to rotate push rod back and forth while slowly tightening adjusting nut. When resistance is felt while rotating push rod, stop tightening adjusting nut. Valve train is now at zero lash. Tighten adjusting nut 1 1/2 turns.
3. Repeat step 2) for intake valves of cylinders No. 5 and 6, and exhaust valves of cylinders No. 1, 2 and 3. Rotate crankshaft one revolution (until cylinder No. 4 is at TDC of compression stroke).
4. Repeat step 2) for intake valves of cylinders No. 2, 3 and 4, and exhaust valves of cylinders No. 4, 5 and 6. Install rocker arm cover and gasket.

TROUBLE SHOOTING

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

FUEL PRESSURE RELEASE

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.

Disconnect negative battery cable. Loosen fuel tank cap to relieve tank pressure. Internal constant bleed feature relieves fuel system pressure in fuel lines and TBI unit when ignition switch is turned off. No further pressure release is required.

ENGINE

1. Release fuel pressure. See FUEL PRESSURE RELEASE. Disconnect negative battery cable. Remove hood. Drain cooling system. Disconnect upper radiator hose from radiator.
2. Remove coolant overflow hose, upper fan shroud, radiator and fan/clutch assembly. Remove air cleaner. Disconnect fuel lines, electrical connectors, vacuum hoses, coolant hoses and control cables as necessary. Remove distributor cap. Raise and support vehicle.
3. Remove exhaust pipe between converter and exhaust manifolds. Remove engine strut rods from bell housing. Remove flexplate/flywheel cover (if equipped). Remove torque converter bolts (A/T). Remove rear shield from converter.
4. Disconnect converter hanger at exhaust pipe. Remove lower fan shroud and 2 outer air dam bolts. Remove left body mount bolts. Raise body to access bell housing bolts. Remove bell housing bolts. Lower body. Remove motor mount through bolts.
5. Lower vehicle. Remove A/C compressor and P/S pump with hoses connected and lay aside (if equipped). Support transmission and remove engine. To install, reverse removal procedure. Fill cooling system.

Removal

1. Release fuel pressure. See FUEL PRESSURE RELEASE. Drain cooling system. Disconnect negative battery cable. Remove air cleaner.
2. Disconnect fuel lines, electrical connectors, vacuum hoses, coolant hoses and control cables as necessary. Mark distributor position and remove distributor. Remove rocker arm covers. Remove intake manifold bolts and nuts. Remove intake manifold and gaskets.

Installation

1. Inspect intake manifold-to-cylinder head gasket surface warpage. If warpage exceeds.005" (.13 mm), replace intake manifold. Apply 3/16" (5 mm) bead of RTV sealant to front and rear intake manifold-to-cylinder block sealing surfaces; extend RTV sealant bead 1/4" (6 mm) beyond cylinder block-to-cylinder head junctions.
2. Position new intake manifold gaskets on cylinder heads, cutting gaskets as necessary to fit behind push rods. Ensure all holes are aligned. Install intake manifold. Tighten intake manifold bolts in sequence to 23 ft. lbs. (31 N.m). (Scheme 9) To install remaining components, reverse removal procedure.

Scheme 9

1. Disconnect negative battery cable. Raise and support vehicle. Disconnect exhaust pipe from manifold. Remove 4 bolts from rear end of exhaust manifold. Lower vehicle.
2. For right manifold, remove heat shield, diverter valve, air pump and alternator brackets. For left manifold, remove heat stove pipe and P/S pump bracket. Remove remaining manifold bolts. Remove manifold and gasket.

Inspect exhaust manifold-to-cylinder head gasket surface warpage. If warpage exceeds .005" (.13 mm), replace exhaust manifold. To install, reverse removal procedure using new gasket. Tighten exhaust manifold bolts to 25 ft. lbs. (34 N.m).

1. Remove intake manifold. See INTAKE MANIFOLD. Drain coolant from cylinder block. Raise and support vehicle. Disconnect exhaust pipe from manifold. Lower vehicle.
2. Remove oil dipstick tube (if removing left cylinder head). Disconnect fuel lines, electrical connectors, vacuum hoses, coolant hoses and control cables as necessary.
3. Remove serpentine belt, alternator and air pump with bracket (if removing right cylinder head). Remove rocker arm nut, rocker arm, pivot ball and push rods. Keep components in order for reassembly. Remove cylinder head bolts. Remove cylinder head and gasket.

1. Ensure cylinder head bolt threads and cylinder block holes are clean. Install cylinder head. Apply GM Sealant (1052080) to head bolt threads. Install head bolts and tighten in sequence to 40 ft. lbs. (54 N.m). (Scheme 10) Tighten head bolts an additional 90 degrees (1/4 turn).
2. To install remaining components, reverse removal procedure. Adjust valves. See VALVE CLEARANCE ADJUSTMENT. Fill cooling system.

Scheme 10

Disconnect negative battery cable. Remove serpentine belt. Remove crankshaft damper bolt. Remove pulley from damper. Raise and support vehicle. Remove damper using Crankshaft Damper Puller (J-24420-B) or (J-23523-E). Using large screwdriver, carefully pry out seal.

Coat sealing lip and damper surface with oil. Install seal using Seal Installer (J-35468). Clean damper key and keyway. Apply GM Sealant (1052336) to keyway. Install damper using Crankshaft Damper Installer (J-29113). Install damper bolt and tighten to 70 ft. lbs. (95 N.m). To complete installation, reverse removal procedure.

1. Remove water pump. See WATER PUMP. Remove Power Steering (P/S) pump bracket (if equipped). Remove crankshaft damper bolt. Remove pulley from damper. Raise and support vehicle.
2. Remove damper using Crankshaft Damper Puller (J-24420-B) or (J-23523-E). Disconnect lower radiator hose from timing chain cover. Remove timing chain cover bolts. Remove cover and gasket.
3. Rotate crankshaft until timing marks on camshaft and crankshaft sprockets align. (Scheme 11) Check timing chain deflection. If timing chain deflects more than 3/8" (9.5 mm) from timing chain damper, replace chain.
4. Remove camshaft sprocket bolts. Remove camshaft sprocket and timing chain. Remove crankshaft sprocket (if necessary).

1. Install crankshaft sprocket (if removed). Apply Molykote to camshaft sprocket thrust surface. Install timing chain over camshaft sprocket. Hold sprocket vertically with chain hanging downward. Align timing marks. (Scheme 11)
2. Install timing chain and camshaft sprocket on camshaft, ensuring sprocket dowel pin hole aligns with camshaft dowel pin. Install and tighten camshaft sprocket bolts to 20 ft. lbs. (27 N.m). Lubricate timing chain with engine oil.
3. Lightly coat both sides of new timing chain cover gasket with anaerobic sealer. Install timing chain cover. Tighten cover bolts to 18 ft. lbs. (24 N.m). To install remaining components, reverse removal procedure. Fill cooling system.

Scheme 11

Remove intake manifold. See INTAKE MANIFOLD. Remove rocker arm nut. Remove rocker arm, pivot ball and push rods. Keep components in order for reassembly. Remove valve lifters.

Note. Some engines are equipped with standard and oversize valve lifters. Oversize lifter usage is indicated by small, White paint dot and/or ".25 mm O.S." stamped near lifter bore.

If installing new lifter, coat bottom of lifter with Molykote. Install lifter in original bore. To complete installation, reverse removal procedure. Adjust valves. See VALVE CLEARANCE ADJUSTMENT.

1. Drain cooling system. Remove radiator. Remove upper fan shroud. Remove valve lifters. See VALVE LIFTERS.
2. Remove timing chain and camshaft sprocket. See TIMING CHAIN & SPROCKETS. Carefully remove camshaft.

Inspection

Measure camshaft journal diameter, lobe lift and oil clearance. See CAMSHAFT table under ENGINE SPECIFICATIONS at end of article. Replace components if measurements are not within specification.

1. Lubricate camshaft bearings and camshaft lobes with GM Lubricant (1051396). Install camshaft. To install remaining components, reverse removal procedure. Ensure timing marks are aligned. (Scheme 11) Install valve lifters and push rods in original location.
2. Adjust valves. See VALVE CLEARANCE ADJUSTMENT. If camshaft is replaced, add GM Engine Oil Supplement (1052367) to engine oil.

Remove transmission and flexplate/flywheel. Note direction of seal installation. Using screwdriver, carefully pry seal from housing in rear main bearing. DO NOT scratch crankshaft sealing surface.

1. Coat inner and outer seal surfaces with engine oil. Install seal on mandrel of Seal Installer (J-34686) until dust lip bottoms against tool collar. (Scheme 12)
2. Align seal installer dowel pin with alignment hole of crankshaft. Install seal installer on crankshaft. Hand tighten seal installer bolts or torque to 36 INCH lbs. (4 N.m).
3. To install seal in housing, tighten seal installer handle until seal installer collar is even with cylinder block. Remove seal installer. To install remaining components, reverse removal procedure.

Scheme 12

Disconnect negative battery cable. Drain coolant. Remove serpentine belt and upper fan shroud. Remove fan/clutch assembly and water pump pulley. Disconnect necessary coolant hoses. Remove water pump bolts and nut. Note bolt lengths and location. Remove water pump and gasket.

Apply GM Sealant (1052080) to bolts. To install, reverse removal procedure using new gasket. Tighten water pump bolts and nut to 22 ft. lbs. (30 N.m). Fill cooling system.

OIL PAN

1. Remove engine. See ENGINE. Remove oil pan bolts. Remove oil pan and gasket.
2. To install, apply GM Sealer (1052914) to half-round section at rear end of oil pan. Install oil pan with new gasket. Tighten 2 bolts at rear end of oil pan to 18 ft. lbs. (24 N.m). Tighten all other bolts to 84 INCH lbs. (10 N.m).

VALVE SPRINGS

Replace valve spring if free length, installed height and pressure are not within specification. Replace valve spring damper if free length is not within specification. See VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS at end of article.

VALVE STEM OIL SEALS

Intake valve uses an upper "O" ring seal and a lower seal. (Scheme 13) Exhaust valve uses only an upper "O" ring seal and an oil shedder/rotator. When installing intake valve lower seal, slide seal over valve stem and valve guide boss. Coat "O" ring seal with engine oil before installation. Ensure seal is not twisted when installed.

VALVE GUIDES

Valve guides are part of cylinder head (not replaceable). If valve stem-to-guide clearance is not .0026-.0068" (.066-.172 mm), ream valve guide and install oversize valve. Oversize valves are available in .003" (.08 mm), .015" (.38 mm) and .030" (.76 mm).

VALVES

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

Scheme 13

ROCKER ARM ASSEMBLY

Clean push rods, rocker arms, balls and nuts with solvent then blow dry. Inspect rocker arms and balls at mating surface for damage. Inspect push rods for bends or wear. Ensure push rod oil passages are clear.

CYLINDER BLOCK ASSEMBLY OVERHAUL

If cylinder block deck surface warpage exceeds .004" (.10 mm), machine surface. Replace cylinder block if more than .010" (.25 mm) material is removed from deck surface.

PISTON & ROD ASSEMBLY

Mark piston position in relation to connecting rod before separating components. Replace piston and pin as matched set. Install piston in cylinder block, with mark on top of piston toward front of engine.

FITTING PISTONS

1. Mark piston and cylinder for reassembly reference. Remove rings from piston. Ensure piston and cylinder are clean. Insert piston into cylinder bore upside down.
2. Piston should free fall in cylinder bore when bottom of piston skirt is 1/2-1" (12-25 mm) from top of deck surface. Try piston in different bore if piston fails to free fall.
3. If piston free falls, correct fit must be determined. Install piston and a .0025" (.060 mm) feeler gauge for used pistons, or .0020" (.050 mm) feeler gauge for new pistons in cylinder bore. Feeler gauge must be at least 6" (152 mm) long and no more than 1/2" (12 mm) wide. Position feeler gauge at 90-degree angle to piston pin.
4. With piston 1/2-1" (12-25 mm) from top of deck surface, note if piston free falls. If piston fails to free fall, piston is correctly fitted for that cylinder. If piston free falls, select a larger diameter piston.

PISTON RINGS

Ensure ring end gap and side clearance are within specification. See PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS at end of article. Install rings with mark on top of ring facing top of piston, and with ring end gaps properly spaced around the piston. (Scheme 14)

Scheme 14

ROD BEARINGS

Mark rods and rod bearing caps for reassembly reference. Rod bearings of .001" (.26 mm) undersize are available. Install rod bearing cap on rod, with bearing tang slot facing away from center of engine. Ensure rod side clearance is .006-.025" (.16-.64 mm).

CRANKSHAFT & MAIN BEARINGS

1. Mark main bearing caps for reassembly reference. Main bearings of.0006" (.016 mm) and.0013" (.032 mm) undersize are available.
2. Apply thin coats of GM Anaerobic Sealant (1052756) and RTV sealant to rear main bearing cap in specified areas. (Scheme 15) Install main bearing caps with arrows facing front of engine. Ensure crankshaft end play is.002-.008" (.06-.21 mm). See THRUST BEARING.

THRUST BEARING

1. Main bearing cap No. 3 is thrust bearing. Tighten main bearing cap bolts, except No. 3 main bearing cap, to 70 ft. lbs. (95 N.m). Tighten No. 3 main bearing cap bolts to 11 ft. lbs. (15 N.m).
2. Using lead hammer, tap crankshaft toward rear of engine then toward front of engine to align crankshaft thrust surfaces. Tighten No. 3 main bearing cap bolts to 70 ft. lbs. (95 N.m). Measure crankshaft end play between front side of No. 3 main bearing and crankshaft thrust surface.

VALVE LIFTER BORES

Some engines may be equipped with oversize valve lifters. Oversize lifter usage is indicated by small, White paint dot and/or ".25 mm O.S." stamped near lifter bore.

Scheme 15

ENGINE OILING SYSTEM

The camshaft-driven gear-type oil pump provides pressurized lubrication through the oil filter, to main gallery above left side of camshaft center line. The main gallery provides lubrication to valve lifters on left bank, camshaft bearings, crankshaft bearings and right gallery.

The right gallery supplies oil to valve lifters on right bank. Rocker arms are lubricated by passages in the push rods. Slot in front camshaft bearing provides lubrication to timing chain. Pistons and piston pins are lubricated by oil splash. Pressure regulator valve is mounted in oil pump body.

CRANKCASE CAPACITY

Engine oil capacity is approximately 4.5 qts. (4.3L) with filter change.

OIL PRESSURE

Normal oil pressure is 50-55 psi (3.5-3.9 kg/cm 2 ) at 2000 RPM.

Removal & Disassembly

1. Remove oil pan. See OIL PAN. Remove oil pump bolt, oil pump and extension shaft from rear main bearing cap. WARNING: Pressure regulator valve spring is under pressure. Use care when removing to prevent personal injury.
2. Remove pump cover. Mark teeth on both gears for reassembly reference. Remove idler gear, drive gear and shaft from pump body. Remove pressure regulator valve retaining pin, valve and spring.

Pump is serviced as an assembly. Replace pump if damaged or excessively worn. Replace pick-up screen tube if loose.

Reassembly & Installation

Coat all internal components with engine oil. To reassemble, reverse disassembly procedure using new cover gasket. Ensure reference mark is aligned on gears. To install, reverse removal procedure. Ensure pump extension shaft is fully engaged.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS

MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS

CONNECTING ROD SPECIFICATIONS

CONNECTING ROD SPECIFICATIONS

PISTONS, PINS & RINGS SPECIFICATIONS

PISTONS, PINS & RINGS SPECIFICATIONS

CYLINDER BLOCK SPECIFICATIONS

CYLINDER BLOCK SPECIFICATIONS

VALVES & VALVE SPRINGS SPECIFICATIONS

VALVES & VALVE SPRINGS SPECIFICATIONS

CYLINDER HEAD SPECIFICATIONS

CYLINDER HEAD SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

See also:
• ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION