6.2l v8 Diesel - Vins [c,j] 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.

Engine code number is suffix of engine identification number. Number is located on label on rear of left valve cover. The Vehicle Identification Number (VIN) is located on a metal plate on top left side of instrument panel, visible through windshield. Engine can be identified by the 8th character of the VIN.

ENGINE IDENTIFICATION CODES

ENGINE

See ENGINE REMOVAL article.

Removal (Pickup)

1. Disconnect batteries. Remove air cleaner. Disconnect PCV hoses, fuel line bracket and ground strap. Loosen vacuum pump hold down clamp and rotate pump to gain access to intake manifold bolt.
2. Remove EPR/EGR valve bracket and rear A/C bracket, if equipped. Remove intake manifold bolts and fuel line clips. Remove intake manifold from engine.

Installation (Pickup)

Clean all gasket surfaces. Install new manifold gaskets. Ensure light duty uses gasket with open EGR passage and heavy duty with closed passage. Install intake manifold and tighten bolts in proper sequence. Reverse removal procedure to complete installation.

Removal (Van)

1. Disconnect batteries. Remove engine cover and air cleaner. Disconnect necessary wires and hoses and remove EGR/EPR switches. Remove crankcase depression regulator valve and disconnect hoses to valve.
2. Remove crankcase depression regulator valve hoses from intake manifold. Remove rear A/C compressor bracket, if equipped. Remove fuel filter-to-intake manifold bracket.
3. Remove vacuum pump. Place a rag or cover over hole to prevent foreign material from entering engine. Remove intake bolts and fuel line clips. Remove intake manifold.

Installation (Van)

Clean all gasket surfaces. Install new manifold gasket. Ensure EGR passage in gasket is opened if vehicle is equipped with EGR. Install intake manifold and tighten bolts in proper sequence. Reverse removal procedure to complete installation.

Intake Manifold Tightening Sequence. Tighten bolts gradually to 31 ft. lbs. (42 N.m). Scheme 34

Removal (Pickup - Right Side)

Disconnect batteries. Raise vehicle. Disconnect exhaust pipe from manifold flange. Lower vehicle. Disconnect glow plug wires and glow plugs. Remove air cleaner duct bracket. Remove manifold bolts and manifold.

Removal (Pickup - Left Side)

Disconnect batteries. Remove dipstick tube nut and tube. Disconnect glow plug wires and remove glow plugs. Remove manifold bolts. Raise vehicle. Disconnect exhaust pipe from manifold flange. Remove manifold from bottom.

Removal (Van - Both Sides)

Disconnect batteries. Raise vehicle. Disconnect exhaust pipe from manifold flange. Lower vehicle. Disconnect glow plug wires. Remove A/C bracket if equipped. Remove manifold bolts and manifold.

Installation (All Models)

To install, reverse removal procedure.

1. Remove intake manifold. Remove injection line clips from brackets. Disconnect injection lines from injector nozzles and cover nozzles. Remove injection lines at pump and mark for reassembly reference.
2. Remove fuel supply line from injection pump. Remove wiring harness and bracket from engine. Remove valve cover. Drain coolant. Remove dipstick tube. Disconnect ground wire from cowl at right side of engine.
3. Raise vehicle. Disconnect exhaust pipe from manifold. Lower vehicle. If equipped, remove A/C compressor from engine without disconnecting refrigerant lines and lay it on left side of engine compartment.
4. Remove alternator from engine and lay it on right side of engine compartment. Disconnect glow plug wires. Remove rocker arm assemblies and push rods. Note their positions to allow reinstallation in the same position.
5. Disconnect radiator, heater and by-pass hoses. Disconnect ground strap. Remove thermostat crossover/housing from cylinder head. Remove cylinder head bolts and cylinder head.

1. Reverse removal procedure to install cylinder heads. Left rear cylinder head bolt must be installed in cylinder head prior to placing cylinder head on engine.
2. Ensure gasket surfaces on head and cylinder block are clean and cylinder head bolt threads and threads in block are clean. Gasket requires no sealer. Coat cylinder head bolt threads and underside of bolt heads with sealer.
3. Tighten cylinder head bolts in 3 steps. First tighten bolts in sequence to 20 ft. lbs. (25 N.m). Retighten bolts in sequence to 50 ft. lbs. (65 N.m). Tighten bolts in sequence an additional 90°. Push rods must be installed with the painted end up.

Cylinder Head Tightening Sequence. Tighten bolts in 3 steps. Scheme 35

1. Remove intake manifold. Install protective covers. Remove injection line clips from brackets. Raise vehicle. Disconnect injection lines from injector nozzles and cover nozzles.
2. Lower vehicle. Remove injection lines at pump and tag lines for reinstallation. If equipped with cruise control, remove transducer. If A/C equipped, remove upper fan shroud and A/C belt.
3. Raise vehicle. Disconnect exhaust pipes from manifolds. Remove left exhaust manifold. Remove power steering lower adjusting bolts. Disconnect glow plug wires and temperature switch. If A/C equipped, remove rear A/C brace from exhaust manifold. Disconnect glow plug wires.
4. Lower vehicle. If A/C equipped, discharge A/C system. Disconnect A/C lines at compressor and remove compressor from brackets. Remove compressor. Remove upper power steering attachment and move aside.
5. Loosen dipstick tube front bracket and remove from stud. Remove oil fill tube upper bracket. Disconnect transmission detent cable. Remove glow plug controller and bracket. Remove glow plug relay.
6. Disconnect oil pressure switch and loom. Remove loom bracket and vacuum line clip bolt at head. Remove rocker cover bolts. Disconnect fuel return line bracket. Remove rocker cover. Remove rocker cover bolts. Disconnect fuel return line bracket. Remove rocker cover.
7. Remove rocker arm assemblies and push rods. Note their positions to allow reinstallation in the same location. Drain cooling system. Remove air cleaner resonator and bracket. Remove transmission fill tube nut and position aside. Disconnect heater, radiator and by-pass hoses at crossover.
8. Remove alternator upper bracket, coolant crossover and cylinder head bolts. Disconnect transmission dipstick at rear of right head and remove tube. Remove cylinder head.

1. Reverse removal procedure to install cylinder heads. Left rear cylinder head bolt must be installed in cylinder head prior to placing cylinder head on engine.
2. Ensure gasket surfaces on head and cylinder block are clean and cylinder head bolt threads and threads in block are clean. Gasket requires no sealer. Coat cylinder head bolt threads and underside of bolt heads with sealer. Tighten cylinder head bolts in sequence in 3 steps. Push rods must be installed with painted end up.

VALVE ARRANGEMENT

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

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

Removal & Installation

Remove valve covers. Loosen rocker arm shaft bolts gradually and evenly to release valve spring pressure. Remove bolts and rocker arm shafts, noting location for reassembly. To install, reverse removal procedure.

Rocker Arm Shaft Mounting. Loosen bolts gradually and evenly. Scheme 36

Removal

With cylinder head removed, compress valve spring and remove valve keepers. Release spring compressor and remove retainer, spring, damper, seal and exhaust valve rotators.

Installation

To install valve springs, reverse removal procedure. Lubricate and install "O" ring type valve stem seal on valve stem before installing remaining components.

VALVE SPRING INSTALLED HEIGHT

Valve spring installed height is measured from top of shim at bottom of spring or spring seat to top of valve spring. If distance exceeds specified height, shim to meet specifications.

VALVE SPRING INSTALLED HEIGHT SPECIFICATIONS

VALVE GUIDE SERVICING

If valve stem-to-guide clearance is excessive, guides can be reamed. Valves with oversize stems are available. Use Reamer (J-7049) to ream guides to correct size for oversize valve stems.

HYDRAULIC VALVE LIFTERS

Note. Hydraulic lifters used are roller type. Lifters are serviced as complete assemblies only. Parts are not interchangeable between lifters.

1. Keep lifters and push rods in order for reinstallation. Remove valve covers, rocker arm shafts and push rods. Remove lifter guide clamps and guide plates. Remove cylinder heads (Van only). Remove lifters using Remover (J-29834).
2. Disassemble and thoroughly clean lifters in clean solvent or diesel fuel. Check for nicks, burrs or scoring on parts. Ensure lifter roller operates smoothly and without excessive play.
3. Prime lifters by working plunger while lifter is submerged in clean kerosene or diesel fuel. Coat roller and bearings with assembly lube. Install lifters into their original position in block. Install lifter guide plate and clamp. Rotate crankshaft 2 full turns while checking to see that lifters are not binding against guide plates.

Exploded View of Hydraulic Valve Lifter. Always prime lifters with oil before installing. Scheme 37

1. Drain coolant from engine. Disconnect negative battery cables. Remove fan belts, fan, fan shroud and pulley. Remove A/C hose bracket nuts. Remove oil fill tube. Remove alternator pivot bolt and drive belt. Remove alternator lower bracket.
2. Remove power steering belt and pump. Remove A/C compressor. Do not disconnect hoses or lines from either device. Support pump and compressor out of the way. Remove A/C compressor belt. Disconnect by-pass and lower radiator hose. Remove water pump bolts. Remove water pump plate and water pump.
3. Rotate engine and align marks on injection pump gear and camshaft gear. Scribe an alignment mark on injection pump flange and on front cover. Remove crankshaft pulley. Remove harmonic balancer using a puller.
4. Remove front cover-to-oil pan bolts. Remove fuel return line clips. Remove injection pump driven gear. Remove injection pump retaining nuts from front cover. Remove baffle and remaining front cover bolts. Remove front cover.

1. Clean sealing surfaces and apply a 3/32" bead of sealer to surface of cover that mates with engine and oil pan. Install front cover and baffle.
2. Install injection pump, aligning marks made during removal. Install injection pump drive gear. Align timing marks on pump gear and cam gear. To complete installation, reverse removal procedure.

Removal & Installation (With Cover Removed)

Pry seal out of cover with a screwdriver. Install new seal with open end of seal toward inside of cover and drive into position. Support cover at seal area before driving in seal.

Removal & Installation (With Cover Installed)

With harmonic balancer removed, pry seal out of front cover. Install seal with open end of seal toward engine and drive into place with Driver (J-22102) and hammer.

Remove front engine cover as previously outlined. Remove bolts securing camshaft gear. Remove injection pump drive gear. Remove cam sprocket, crank sprocket and timing chain.

Install camshaft sprocket, crankshaft sprocket and timing chain. Ensure timing marks on sprockets are aligned. Install and tighten sprocket bolts. Rotate crankshaft 360°. Install front cover as previously outlined. Align marks on injection pump gear and injection pump drive gear. Whenever the timing chain, sprockets or gears are replaced, it is necessary to retime the engine.

1. Disconnect batteries. Drain cooling system. Remove intake manifold, engine front cover and timing chain. Remove valve covers, rocker arms and push rods. Keep parts in order for reinstallation. Disconnect exhaust pipe from manifolds.
2. Remove cylinder heads with exhaust manifolds attached. Remove grille, A/C condenser and radiator (if necessary). Remove vacuum pump. Remove lifters, guide plates and clamps. Keep parts in order for reinstallation. Remove fuel pump. Remove camshaft retainer plate and camshaft.

Lubricate camshaft journals and lobes with motor oil. If a new camshaft is being installed, coat camshaft lobes with Molykote. Position camshaft to align timing marks on sprockets. Install remaining components in reverse order of removal.

Timing Chain Sprocket Alignment. Scheme 38

1. Disconnect batteries. Drain cooling system. Remove headlight bezels, grille and bumper. Remove lower valance panel, hood latch, coolant recovery bottle and upper tie bar. If A/C equipped, disconnect lines and remove condenser.
2. Disconnect low coolant wire and engine oil cooler lines at radiator. Disconnect automatic transmission cooler lines, if equipped. Disconnect upper and lower radiator hoses. Remove radiator and fan assembly.
3. Remove cylinder heads. Remove alternator lower bracket, water pump and crank pulleys. Using Damper Remover (J-23523-E) and Pilot (J-29788), remove torsional damper. Remove timing cover plate and water pump. Rotate crankshaft and align timing marks. Remove injection pump driven gear and inner baffle.
4. Align injection pump and front cover by scribing a line across pump flange and front cover. Remove front cover, fuel pump and lifters. Remove injection pump drive gear, timing chain and crankshaft gear. Remove camshaft retainer plate and camshaft.

Lubricate camshaft journals and lobes with motor oil. If a new camshaft is being installed, coat camshaft lobes with Molykote. Position camshaft to align timing marks on sprockets. Install remaining components in reverse order of removal.

CAM LOBE LIFT

With valve cover removed, remove rocker arm. Mount dial indicator on cylinder head. Position indicator stem on push rod with Adapter (J-8520). Rotate engine slowly until lifter is on heel of camshaft. Zero dial indicator. Rotate engine slowly until push rod is at fully raised position. Dial indicator will give total camshaft lobe lift. Lift should be within specifications.

CAMSHAFT BEARINGS

Use camshaft bearing Remover/Installer (J-6098) to remove bearings. Install front and rear bearings first by driving toward center of cylinder block. Align oil holes in front 4 bearings with oil holes in bearing bore in block. Position rear camshaft bearing oil hole at or near the 6 o'clock position. Install new rear cam bore plug flush with block, using sealer.

OIL PAN

See OIL PAN REMOVAL article.

1. Remove oil pan, oil pump and cylinder heads. Remove ridge at top of cylinder bore with a ridge reamer. Check connecting rod and cap for identification marks or numbers and identify if necessary. NOTE: Each piston is fitted to its individual cylinder and should be marked for that cylinder.
2. Remove connecting rod cap nuts and rod cap. Cover rod bolts with hose to protect crankshaft journals. Push piston and rod assembly up and out of cylinder block. It will be necessary to rotate crankshaft to various positions to facilitate removing piston and rod assemblies.

Note. When cleaning pistons, DO NOT wire brush any part of piston assembly.

1. Before installing piston and rod assembly, position ring gaps. (Scheme 39) Place connecting rod in bore with bearing tang slots facing away from camshaft.
2. Lubricate rod bearings, cylinder bore and crankshaft journal. Compress piston rings and push piston and rod assembly into position. Install rod cap and tighten rod cap nuts to specifications.

Piston Ring Gap Positioning. Stagger ring gaps to minimize compression loss. Scheme 39

FITTING PISTONS

Note. A cylinder requiring only minor clean-up and which has less than .005", (.127 mm) taper or wear may be able to use a high-limit standard size piston instead of boring the cylinder to the next oversize.

1. With piston and rod assemblies removed, wipe cylinder bores clean and measure diameter of cylinder with a dial indicator. If cylinder is worn or is tapered more than.005" (.127 mm), cylinder must be bored for oversize pistons.
2. If bore is worn or tapered less than.005" (.127 mm), cylinder can be cleaned and honed. If cylinders are bored, various oversize pistons are available.
3. To check fit of rings in cylinder bore, insert ring in cylinder bore, push ring into bore 1/4" with head of piston. Measure ring end gap with a feeler gauge.
4. Before installing rings on pistons, ensure ring grooves are clean of carbon and inspect grooves for nicks or burrs. Install rings with gaps staggered. (Scheme 39)

With piston and rod assembly removed from engine, remove piston pin retaining rings. Slide pin out of piston and connecting rod.

Check clearance of pin in piston. If clearance exceeds specifications, piston and pin must be replaced. Lubricate piston pin and install into piston and rod. Secure pin with retaining rings. Rotate retaining rings in their grooves to ensure that they are completely seated. Check piston for freedom of movement on piston pin.

CONNECTING ROD BEARINGS

Note. Following procedures are performed with oil pan and oil pump removed.

1. Mark or identify rod cap and rod pairs before removing rod cap nuts. With rod nuts removed, remove rod cap and bearing. Cover rod bolts with hose to protect crankshaft. Push up on piston and rod assembly and remove bearing from rod. Inspect bearings for wear or damage and replace as necessary.
2. Check crankshaft rod bearing journal for out-of-round or taper conditions. If crankshaft is out-of-round or is tapered more than .0002" (.005 mm), crankshaft must be replaced. Check crankshaft clearance using the Plastigage method.
3. If clearance exceeds specifications, an undersize bearing may be installed to obtain correct clearance. If clearance is still excessive, crankshaft must be replaced.
4. To install bearings, clean crankshaft journal and bearing surface in rod. Insert bearing in rod and cap. Lubricate journal and pull piston and rod assembly down, aligning bearing on journal. Install rod cap noting identification marks and tighten rod nuts evenly.

CRANKSHAFT MAIN BEARINGS

1. Main bearings are selective fit by manufacturer during production. A standard size bearing may be used in combination with an undersize bearing to obtain correct clearance.
2. Main bearings may be removed and replaced with crankshaft still installed in engine. Mark or identify main bearing caps to cylinder block before removing caps. Remove bearings from cylinder block.
3. Crankshaft clearance, taper or out-of-round conditions can be checked using the Plastigage method. If clearance exceeds specifications, an undersize bearing may be installed to obtain correct clearance. Both bearings must be replaced on any journal not within specifications.
4. If correct clearance cannot be obtained or if journal is tapered or is out-of-round more than .0002" (.005 mm), crankshaft must be replaced. To install bearings, ensure crankshaft journal and bearing surface in cap and block are clean.
5. Lubricate journal and install bearing cap. If bearings were removed with crankshaft installed, use bearing remover/installer inserted in crankshaft oil hole to install upper bearing. Install main cap and tighten main bearing bolts evenly and to specifications.

CRANKSHAFT END PLAY

Pry crankshaft forward as far as possible and check crankshaft end play with a feeler gauge inserted between front of No. 3 main bearing and crankshaft. Replace thrust bearing if end play is not to specification.

Checking Crankshaft End Play. Use a feeler gauge to check for max of .004-.009" (.10-.25 mm) end play. Scheme 40

REAR MAIN BEARING OIL SEAL

Note. Rear main bearing cap is tapped into place using a brass of leather hammer. The new seal is used as a guide. The cap must not be pulled into the block using bolts.

1. With oil pan and oil pump removed, remove rear main bearing cap and lower half of seal. Withdraw upper half of seal from block. Clean block mating surface. Clean upper and lower seal grooves.
2. Lightly lubricate crankshaft seal contact area with motor oil. Roll one seal half into block seal groove until.50" (13 mm) of one end of seal is extending out of block. Insert remaining seal half into the opposite side of block seal groove. Contact ends of seal halves will be at 4 and 10 o'clock, or 8 and 2 o'clock positions.
3. Place a piece of plastigauge on rear main journal. Install rear main cap and tighten main bearing cap to specifications. Remove rear main cap and check plastigauge for clearance.
4. Lightly coat seal groove in main bearing cap with adhesive (Locktite 414) or equivalent. Apply a thin film of anaerobic sealant to bearing cap. (Scheme 41) Lightly oil bolt threads. Tap main bearing cap into place. Install and tighten in sequence inner bolts 110 ft. lbs. (150 N.m.). Install oil pump and oil pan.

Applying Sealer to Rear Main Bearing Cap. Scheme 41

1. Disconnect batteries. Remove fan and fan shroud. Drain radiator. If A/C equipped, remove A/C hose bracket nuts. Remove oil fill tube. Remove alternator pivot bolt, belt and lower bracket.
2. Remove power steering belt. Remove power steering pump and position aside. Remove A/C belt, if equipped. Disconnect by-pass hose and lower radiator hose. Remove water pump bolts, plate and pump.

Apply anaerobic sealant to sealing surface of plate so that sealer is wet to touch when bolts are tightened. Reverse removal procedure to complete installation.

Note. For further information on cooling systems, see ENGINE COOLING SYSTEM article.

CRANKCASE CAPACITY

Crankcase capacity is 7 qts. (6.6L) including filter change.

OIL FILTER

Replace oil filter every 5,000 miles or 12 months, whichever comes first.

NORMAL OIL PRESSURE

Normal oil pressure should be 40-45 psi (2.81-3.16 kg/cm 2 ) at 2000 RPM.

OIL PRESSURE REGULATOR VALVE

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

ENGINE OILING SYSTEM

Full pressure lubrication through a full flow oil filter and oil cooler is supplied by a gear-type oil pump. Main oil gallery feeds oil through drilled passages to camshaft and crankshaft to lubricate bearings. Valve lifter gallery feeds the valve lifters, which feed the rocker arms through hollow push rods.

Remove oil pan. Remove pump-to-rear main bearing cap bolt. Remove oil pump and extension shaft.

Disassembly

1. Remove pump cover attaching screws and pump cover. Mark gears so they may be reassembled with same tooth indexing. Remove idler gear, drive gear and shaft from pump housing.
2. Remove pressure regulator valve retaining pin from pump cover. Remove regulator valve from pump cover. Do not disassemble pick-up screen and pipe. Screen and pipe are only serviced as an assembly with the pump.

Note. If pump gears or body are damaged or worn, replacement of the entire pump assembly is necessary.

Reassembly & Installation

Clean and check all parts for fit and wear. Reverse removal and disassembly procedure to assemble and install. Check operation of pump before installing. Bottom of screen must be parallel with bottom of pan.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS (LIGHT DUTY)

GENERAL ENGINE SPECIFICATIONS (HEAVY DUTY)

VALVE SPECIFICATIONS

VALVE SPECIFICATIONS

PISTON/PIN/RING SPECIFICATIONS

PISTONS, PINS & RINGS SPECIFICATIONS

BEARING SPECIFICATIONS

CRANKSHAFT MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS

VALVE SPRING SPECIFICATIONS

VALVE SPRING SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

See also:
• ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION