2.8l v6 - Vins [b,r] GMC Cab & Chassis S15

ENGINE IDENTIFICATION

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

The engine identification number is stamped on a machined pad on front of cylinder block to the rear of engine front cover. The Vehicle Identification Number (VIN) is located on left side of dash panel at base of windshield. The eighth character of the (VIN) denotes engine type.

ENGINE IDENTIFICATION CODES

Valve Arrangement

Left Bank - E-I-I-E-I-E (Front-to-rear).

Right Bank - E-I-E-I-I-E (Front-to-rear).

1. Rotate crankshaft to bring No. 1 piston to TDC of compression stroke. Both No. 1 valves will be closed. Back off adjusting nut until lash (play) is felt at push rod.
2. Tighten nut until all lash is removed. Tighten adjusting nut an additional 1 1/2 turns. Adjust valves using specified sequence. See «VALVE CLEARANCE ADJUSTMENT»(/gmc/cab-chassis-s15/1985-1988/remont/mechanical/#28l-v6-vins-br) table.
3. Rotate crankshaft 360° to bring No. 4 piston to TDC of compression stroke. Adjust remaining valves and replace rocker arm covers.

VALVE CLEARANCE ADJUSTMENT

Valve Clearance Adjustment. Tighten adjusting nut 1 1/2 turns after lash is eliminated. Scheme 11

ENGINE

See ENGINE REMOVAL article.

Removal

1. Remove air cleaner and negative battery cable. Drain cooling system. Disconnect all electrical connectors, vacuum hoses and cables at distributor and TBI unit.
2. Disconnect fuel line(s), distributor cap and ignition wires. Mark position of rotor and remove distributor. Remove rocker arm brackets and rocker arm covers.
3. Remove upper radiator hose and heater hose from engine. Remove A/C drive belt and rotate compressor away from work area. Remove intake manifold and discard gaskets.

Scheme 12

1. Clean gasket mating surfaces. Apply 3/16" bead of silicone sealant to front and rear sealing ridges of cylinder block. Remove carbon build-up from exhaust and EGR ports.
2. Install new manifold side gaskets onto cylinder heads following manufacturer's instructions. Secure by applying silicone sealant on ends of side gaskets. Cut new side gaskets for installation behind push rods. (Scheme 12): Intake Manifold Tightening Sequence. Carbureted manifold shown; TBI manifold is similar.
3. Install intake manifold without disrupting gasket position. Install and tighten manifold attaching bolts and nuts. (Scheme 12) To complete installation, reverse removal procedure.

Remove negative battery cable. Raise vehicle and separate exhaust pipe from manifold. On left side, remove 4 rear manifold bolts and one nut. Lower vehicle. On both sides, disconnect air diverter valve, hoses and wires. Remove power steering bracket. Remove manifold bolts and manifold.

Installation

To install, clean manifold-to-head mating surfaces and reverse removal procedure.

1. Remove intake manifold and raise vehicle. Disconnect exhaust pipe from manifold and drain cooling system. Remove oil dipstick and tube assembly. Remove alternator with bracket, and lower vehicle.
2. Remove rocker arm covers, rocker arms and push rods in sequence for reinstallation in original locations. Remove power steering pump and A/C compressor (if equipped), with mounting brackets. Remove cylinder head bolts and separate cylinder head from engine.

1. Clean gasket mating surfaces, head bolts and cylinder block threads. Position head gaskets on cylinder block with marked side up. Install cylinder heads. Apply sealant to head bolt threads and install bolts. Tighten bolts in sequence. (Scheme 13)
2. Coat rocker arm balls and rocker arm mating surfaces with assembly lubricant before installing. To complete installation, reverse removal procedure and adjust valves.

Cylinder Head Tightening Sequence. Tighten head bolts to 55-77 ft. lbs. (74-108 N.m). Scheme 13

ROCKER ARM STUDS

Replace damaged rocker arm studs with new studs. If threads in head are damaged, the head can be retapped and a helical insert installed. If a helical insert is not available, replace cylinder head.

Note. The following procedure is designed for repair without cylinder head removal. If cylinder head is removed, proceed to step 2 .

1. Remove rocker arm cover, spark plug, rocker arm and push rod of cylinder to be serviced. Install air hose and adapter to spark plug hole. Apply constant air pressure of 90 psi (6.3 kg/cm 2 ).
2. Using a valve spring compressor, compress valve spring and remove valve retainer locks and oil seal. Release compressor and remove retainer/rotator, oil shield (exhaust only), and valve spring damper. On intake valves, remove teflon oil seal. (Scheme 15)

Intake and Exhaust Valve Assemblies. Teflon oil seal is used with "O" ring seal on intake valves. Scheme 14

Inspection

Check valve spring tension with tester. Springs (without dampers) should test within 10 lbs. of specification. Replace spring if not within limits.

1. Position valve spring and damper on cylinder head. Install teflon oil seal on intake valve and oil shield on exhaust valve. Install retainer/rotator on valve spring.
2. Coat "O" ring type seal and valve stem with engine oil. Compress spring and install seal in lower groove of valve stem. Ensure seal is not twisted in groove. Install retainer locks and release compressor. Ensure retainer locks are properly seated in upper groove of valve stem.

VALVE SPRING INSTALLED HEIGHT

Installed height of valve springs should be 1.58" (40 mm). For intake valves, measure from top of spring damper tabs to bottom of retainer. For exhaust valves, measure from top of spring damper tabs to where top of valve spring contacts inside bottom of oil shield. If measurement exceeds specified height, install a .030" (.76 mm) shim at spring seat.

VALVE GUIDE SERVICING

If valve stem-to-guide clearance exceeds specifications, ream valve guide to proper oversize. Valves are available with oversize stems. If oversize stems are used, oversize oil seals must be used.

HYDRAULIC VALVE LIFTERS

If lifters are removed, they must be installed in original positions. Service lifters as complete assemblies only. If lifters are disassembled and cleaned, they should be tested in a lifter leak-down rate tester prior to installation. (Scheme 15)

Hydraulic Lifter Assembly. Service lifters as complete assemblies only. Scheme 15

Some engines may have both standard and.010" (.25 mm) oversize valve lifters. Engines with oversize lifters will be marked with a dab of White paint and "0.25 O.S." stamped on lifter boss. (Scheme 16)

Identifying Oversize Lifters. Lifter bosses are also marked with a dab of White paint. Scheme 16

Remove negative battery cable and all drive belts. Drain cooling system and remove water pump. If equipped, remove A/C compressor and mounting bracket. Remove vibration damper. Disconnect lower radiator hose at front cover and heater hose at water pump. Remove front cover with retaining bolts and gasket.

1. Clean sealing surfaces thoroughly. Apply 3/32" bead of RTV sealant to front cover-to-block sealing surface. Apply 1/8" bead silicone sealant to bottom of front cover sealing surface. (Scheme 17)
2. Place front cover on engine and install stud bolt with 2 lower bolts. Coat water pump bolts with pipe thread sealant. Apply 3/32" bead RTV sealant to water pump sealing surface. Install water pump and attaching bolts. To complete installation, reverse removal procedure. See «TORQUE SPECIFICATIONS»(/gmc/cab-chassis-s15/1985-1988/remont/mechanical/#28l-v6-vins-br__torque-specifications).

Front Cover Sealant Application. Do not allow sealant to cure before installation. Scheme 17

Oil seal may be replaced with front cover installed. Remove vibration damper. Using large screwdriver, pry seal out of cover. Use care not to damage crankshaft sealing area or front cover.

Lubricate and install new seal with open side of seal toward inside of front cover. Use Seal Installer (J-35468) to drive seal into position. Install vibration damper. See TORQUE SPECIFICATIONS .

1. Remove front cover. Rotate crankshaft to position No. 4 piston to TDC of compression stroke. Timing marks on camshaft and crankshaft sprockets should be aligned. No. 1 piston will be at TDC of exhaust stroke. (Scheme 18)
2. Remove camshaft sprocket bolts, sprocket and chain. If camshaft sprocket resists removal, use a soft faced hammer and lightly tap lower area of sprocket. Avoid letting camshaft or crankshaft turn.

Install timing chain and camshaft sprocket. Timing marks must be aligned. (Scheme 18) Use attaching bolts to draw sprocket onto camshaft and tighten bolts. Lubricate chain with engine oil. Install remaining components in reverse order of removal.

Aligning Timing Sprockets. Avoid letting camshaft or crankshaft turn during removal. Scheme 18

Allow engine to cool. Drain cooling system. Remove radiator and condenser if A/C equipped. Remove fuel pump, front cover and intake manifold. Remove rocker arm assemblies, push rods and valve lifters in sequence for installation in original locations. Remove timing chain and sprocket. Carefully remove camshaft, avoiding damage to camshaft bearings.

Lubricate journals with oil and camshaft lobes with assembly lubricant. Carefully install camshaft. Lubricate rocker arm ball and valve contact surface. To complete installation, reverse removal procedure.

CAM LOBE LIFT

1. Remove rocker arm assemblies. Mount dial indicator with ball socket adapter on push rod. Rotate engine clockwise until lifter is on the base camshaft lobe and zero dial indicator.
2. Rotate engine until push rod is fully raised. Record lobe lift reading and compare with specifications. Intake lobe lift is .231" (5.87 mm), and exhaust lift is .263" (6.67 mm). Replace camshaft and lifters if not within limits.

Note. Camshaft bearing replacement is performed with engine out of vehicle and crankshaft removed.

Remove camshaft. Push pistons to top of bores. Remove camshaft rear cover from cylinder block. Index camshaft bearing remover/installer tool pilot in front camshaft bearing. Remove front and rear bearings after all other bearings have been extracted.

Using bearing remover/installer, install front and rear bearings first. These act as remover/installer guide and center the remaining bearings being pulled into place. Ensure bearing oil holes line up with oil gallery holes in block. To complete installation, reverse removal procedure.

OIL PAN

See OIL PAN REMOVAL article.

1. Remove oil pan, oil pump and cylinder heads. Place piston at lower end of stroke and cover with cloth to collect cuttings. Use a ridge reamer to clean ridge or deposits from upper portion of the cylinder bore.
2. Mark connecting rod and cap for installation in original location. Remove connecting rod cap and install rubber hose over rod bolts. Push piston and rod out top of bore, and install cap to connecting rod.

1. Install rings on piston, and position ring gaps. (Scheme 19) Apply a light coat of engine oil to piston, rings and cylinder bore. Compress piston rings with ring compressor, ensuring ring gaps do not change.
2. Cover rod bolts with protective rubber hose. Install piston with notch (or machined hole) in piston head, toward front of engine. Rod bearing tang slot must be positioned away from camshaft. Remove rubber hose from rod bolts. Install rod caps with bearings and tighten to 37 ft. lbs. (50 N.m).

FITTING PISTONS

1. Using telescopic gauge and micrometer, measure cylinder bore diameter. Measure piston diameter across piston skirt, at center of piston pin. Difference between 2 measurements is piston-to-cylinder clearance.
2. Using cylinder bore gauge, measure cylinder bore taper by working gauge up and down in bore. Difference between high and low readings is taper. Taper must not exceed .004" (.10 mm).
3. Measure cylinder bore out-of-round by rotating bore gauge horizontally around circumference of bore. Cylinder out-of-roundness can be determined by variation of gauge reading and must not exceed .004" (.10 mm).
4. If taper or out-of-round are not within limits, rebore cylinders. Replacement pistons are available in standard, .020" (.50 mm) and .040" (1.0 mm) oversizes. When reboring cylinders, all main bearing caps must be installed and tightened.

FITTING RINGS

1. Position ring at bottom of cylinder bore, about 1/4" above ring travel. Ring must be square in bore. Measure ring end gap with a feeler gauge. See «PISTONS, PINS & RINGS SPECIFICATIONS»(/gmc/cab-chassis-s15/1985-1988/remont/mechanical/#28l-v6-vins-br) table.
2. Before installing compression rings on pistons, check side clearance. Insert outer edge of ring in groove and slide ring around circumference of piston. The ring should slide freely in groove. If ring grooves have high steps on lower lands, piston must be replaced.
3. Check side clearance of compression rings with feeler gauge inserted between ring and ring groove. Install and properly space rings on piston. Oil ring spacer ends must be butted, not overlapped. Note that oil ring spacer anti-rotation tang is inserted into oil hole (or slot) of piston. Insert oil ring spacer tang in piston oil hole (or slot). Hole is within arc of oil ring spacer gap "A". (Scheme 19)

Desired Ring Gap Locations. Scheme 19

Remove piston compression and oil rings. Using Piston Pin Tool (J-24086), press pin from piston and connecting rod.

Check clearance of pin in piston. Replace piston and pin assembly if not within limits. Lubricate piston and connecting rod pin bores. Assemble connecting rod to piston. Using Piston Pin Tool (J-24086), press piston into place. Check piston for freedom of movement on pin.

CONNECTING ROD BEARINGS

Note. Crankshaft bearings cannot be shimmed for adjustment. Never file or grind connecting rods or caps when fitting bearings.

1. With crank journal and bearing clean, place Plastigage across full width of bearing, about 1/4" off center and away from oil holes. Install and tighten rod cap. Do not let crankshaft turn.
2. Remove rod cap and determine clearance by measuring width of compressed Plastigage at widest point. If clearance is excessive, select a new undersize bearing and remeasure clearance.
3. Clean crankshaft journal and bearing seat in rod and cap. Insert bearings in rod and cap and coat with engine oil. Pull piston and rod assembly onto crankshaft and install rod cap. After all rods are installed, check side play between rod cap and crank pin thrust face.
4. Replacement bearings are available in standard, .0005" (.013 mm) and .0010" (.026 mm) undersizes for use with standard size crankshaft.

MAIN BEARINGS

Note. If the lower bearings (except No. 1) do not indicate excessive wear or damage, it can be assumed that the upper bearings are also acceptable.

Note. Crankshaft bearings cannot be shimmed for adjustment. Never file or grind connecting rods or caps when fitting bearings.

1. Use Plastigage method to check bearings. If engine is in vehicle, crankshaft must be supported at front and rear. Ensure that all bearing caps, other than the one being checked, are tightened to specifications. When checking No. 1 main bearing, remove all drive belts from crankshaft pulley.
2. Start with rear main bearing cap and work forward. New bearings are available in standard, .006" (.15 mm) and .012" (.30 mm) undersizes. Always replace both upper and lower bearing halves together.
3. Remove main bearings from cylinder block by inserting bearing remover/installer in crankshaft oil hole. Rotate crankshaft clockwise. If remover/installer is unavailable, use a bent cotter pin.
4. Lubricate journal and bearing. Insert plain end of bearing between crankshaft and notched side of block. With bearing remover/installer in crankshaft oil hole, rotate crankshaft counterclockwise to install bearing.
5. Install lower bearing half into cap and lubricate with engine oil. Install and tighten main bearing cap with arrow pointing toward front of engine.

THRUST BEARING ALIGNMENT

1. Ensure all main bearing caps, except No. 3, are installed and tightened. Tighten No. 3 thrust bearing cap bolts to 11 ft. lbs. (15 N.m).
2. Tap end of crankshaft back and forth to line up main bearing and crankshaft thrust surfaces. Tighten thrust bearing cap. Retighten all main bearing cap bolts, including thrust bearing. Rotate crankshaft to confirm free movement.

CRANKSHAFT END PLAY

Check crankshaft end play after aligning thrust bearing. Pry crankshaft forward and insert feeler gauge between crankshaft thrust surface and front of No. 3 main bearing cap. End play should be .002-.008" (.05-.21 mm).

Removal (Thin Seal Type)

Remove oil pan, oil pump and rear main bearing cap. Remove upper and lower rope seal. Loosen No. 2 and 3 main bearing bolts if necessary. Clean seal channel.

Scheme 20

Scheme 21

1. Apply a thin coat of gasket sealer to outside of rubber seal, keeping sealer off seal lips. Roll seal into position in cylinder block. Use a piece of shim stock to slip between seal and block to prevent seal damage. Turn crankshaft to ease installation. Seal lip must face front of engine and seal dust lip must face flywheel. (Scheme 20) (Scheme 20): Cross Section of Rear Main Seal. Install seal using shim stock to prevent seal damage.
2. Apply gasket sealer to other half of seal and install in rear main bearing cap. Apply a 1/32" bead of anaerobic sealer to cap between rear main seal end and oil pan rear seal groove. Keep sealer off rear seal, bearing and drain slot. (Scheme 21) (Scheme 21): Applying Sealer to Rear Main Bearing Cap
3. Apply light coat of engine oil to crankshaft surface at seal. Install rear main bearing cap. Tighten bearing cap bolts. Use Plastigage method to check bearings. Install oil pump and pan.

Note. The thick, main bearing oil seal is a one-piece unit that can be serviced without removal of oil pan or crankshaft.

Removal (Thick Seal Type)

Remove transmission, clutch housing and flywheel, or drive plate. Pry rear main bearing oil seal out with a screwdriver. Avoid damage to surrounding area.

1. With lip of seal facing toward front of engine, center seal over end of crankshaft. Install seal with Rear Main Seal Installer Tool (J-34686). Ensure that seal is fully seated in groove.
2. Take care to prevent seal from binding and not seating properly. Install converter drive plate or flywheel, clutch assembly, clutch housing and transmission.

Disconnect negative battery cable. Allow engine to cool and drain cooling system. Remove heater hose from water pump. Remove water pump.

Apply 3/32" bead of anaerobic sealer to water pump sealing surface. Coat bolt threads with pipe thread sealer. Install and tighten water pump. Install remaining components in reverse order of removal.

Note. For further information on cooling system capacities and other cooling system components, see ENGINE COOLING SYSTEMS article.

CRANKCASE CAPACITY

Crankcase capacity is 4.5 quarts (4.2L) with oil filter replacement.

NORMAL OIL PRESSURE

Normal oil pressure is 10 psi (.7 kg/cm 2 ) at 500 RPM and 50-55 psi (3.5-3.9 kg/cm 2 ) at 2000 RPM. Oil pressure should be measured with engine at operating temperature.

OIL PRESSURE REGULATOR VALVE

Oil pressure regulator valve is located in oil pump body. Valve is nonadjustable.

ENGINE OILING SYSTEM

The left main oil gallery (along upper left side of camshaft) supplies oil to the left bank hydraulic lifters. The left gallery directs oil to the camshaft bearings, crankshaft and right oil gallery.

The right oil gallery supplies oil to the right side hydraulic lifters. From valve lifters, oil is supplied to upper valve train through hollow push rods. All other components are lubricated by splash or nozzle method.

With engine removed from vehicle, remove oil pan. Remove bolt attaching oil pump to rear main bearing cap, then remove oil pump with extension shaft.

Disassembly

1. Remove pump cover. Mark gears at a meshing point, so they may be reassembled with same gear teeth indexing. Remove idler gear and drive gear and shaft from pump body.
2. Remove pressure regulator valve retaining pin, valve and spring. Remove oil inlet tube from body, if it needs replacement. Do not remove screen on oil inlet tube.

Note. If pump gears or body are damaged or worn, the entire pump assembly must be replaced.

Wash all parts and dry with compressed air. Inspect pump body, pump cover and pump gears for damage or excessive wear. Check drive gear shaft for looseness in pump body. Inspect oil inlet tube and screen for damage. Check pressure regulator valve for fit in bore.

Reassembly

1. If removed, install oil inlet tube and screen. Apply sealer to end of tube, and tap tube into place, using plastic hammer. Install pressure regulator valve, spring and retaining pin.
2. Install idler gear and drive gear and shaft into pump body. Ensure gear teeth previously marked are indexing. Prime oil pump and install pump cover.

Assemble pump and extension shaft (with retainer) to rear main bearing cap. Ensure top end of hexagon extension shaft engages with hexagon socket of distributor drive gear. Install and tighten oil pump attaching bolt.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

VALVE SPECIFICATIONS

VALVE SPECIFICATIONS

PISTONS, PINS & RINGS SPECIFICATIONS

PISTONS, PINS & RINGS SPECIFICATIONS

CRANKSHAFT MAIN & CONNECTING ROD BEARINGS SPECS

CRANKSHAFT MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS

VALVE SPRING SPECIFICATIONS

VALVE SPRING SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

See also:
• ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
• VALVE CLEARANCE ADJUSTMENT
• TORQUE SPECIFICATIONS