4.1l 6-cyl - VIN [d] GMC Vandura I

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 a letter code in eighth position of Vehicle Identification Number (VIN). The VIN is stamped on a metal tab, attached to left side of dash, near windshield. Engine identification number is also stamped on a machined pad, at right hand side of cylinder block, rearward of distributor bore.

ENGINE IDENTIFICATION CODES

Valve Arrangement

E-I-I-E-E-I-I-E-E-I-I-E (Front to rear)

1. Remove distributor cap. Mark distributor housing at No. 1 and No. 6 rotor firing positions.
2. With distributor rotor in the positions designated in Valve Adjustment table, adjust valves as follows: Loosen rocker arm adjusting nut until push rod lash (play) is felt. Tighten adjusting nut until all lash is removed. When lash has been removed, tighten adjusting nut 1 full turn to complete procedure.

VALVE CLEARANCE ADJUSTMENT

TROUBLESHOOTING

Note. For troubleshooting of mechanical engine components, see appropriate table in TROUBLESHOOTING article in GENERAL INFORMATION.

ENGINE

1. Disconnect negative battery cable and drain cooling system. Remove engine cover and air cleaner. If equipped, discharge A/C system and remove compressor.
2. Disconnect accelerator linkage from carburetor and remove carburetor. Remove grille and cross brace. Remove windshield washer jar and, if equipped, A/C vacuum reservoir.
3. Disconnect radiator hoses, oil cooler lines (if equipped), A/C condenser bracket (if equipped) and radiator support brackets. Swing A/C condenser out of the way (if equipped) and remove radiator.
4. Remove all hoses, wiring, linkage and lines from engine. Raise vehicle and remove fuel line from fuel pump. Drain crankcase and remove drive shaft. Remove exhaust pipe at manifold and linkage from transmission.
5. Remove speedometer cable and transmission mount bolts. If equipped with manual transmission, disconnect clutch linkage and remove clutch cross shaft. Remove engine mount bolts.
6. Lower vehicle and attach lifting device. Raise engine slightly to remove right hand motor mount. Remove engine with transmission.

EXHAUST MANIFOLD

Note. Intake manifold is integral with cylinder head.

Removal

1. Disconnect negative battery cable at battery. Remove air cleaner. If equipped, remove power steering pump and air pump drive belts. Remove both pumps and mounting brackets. Remove air injection manifold from exhaust manifold.
2. Raise vehicle. Disconnect exhaust pipe from exhaust manifold, and catalytic converter bracket at transmission mount. Lower vehicle. Remove exhaust manifold.

Installation

Ensure gasket surfaces are clean. Place manifold in position with new gasket. Install and tighten exhaust manifold bolts. Reverse removal procedure to complete installation. (Scheme 9)

Exhaust Manifold Tightening Sequence. Scheme 9

1. Drain cooling system and disconnect upper radiator hose at engine. Remove exhaust manifold. Remove rocker arm covers. Remove rocker arm assemblies and push rods in sequence, for reinstallation in original locations.
2. Disconnect and label all wires and vacuum hoses that may interfere with head removal. If equipped, disconnect air injection hose at check valve. Remove cylinder head.

Scheme 10

1. Ensure that gasket surfaces of cylinder head and block are clean, and all head bolt threads and threads in block are clean. Coat threads of head bolts with sealer.
2. To install cylinder head and remaining components, reverse removal procedure. Tighten head bolts in sequence. (Scheme 10) Lubricate rocker arm parts with Molykote (or equivalent). Adjust valves. (Scheme 10): Cylinder Head Tightening Sequence
3. Tighten front left-hand head bolt to 85 ft. lbs. (115 N.m), and all others to 95 ft. lbs. (129 N.m).

ROCKER ARM STUD SERVICE

Rocker arm studs that are loose in head or have damaged threads, can be replaced with oversize studs. Use reamer (J-5715) for .003" (.08 mm) oversize replacement studs, and reamer (J-6036) for .013" (.33 mm) oversize replacement studs.

Remove damaged stud using stud remover (J-5802-A). Install tool over stud. Tighten nut on tool to extract stud from cylinder head.

Ream hole for oversize studs. Coat press-fit area of stud with hypoid axle grease. Drive rocker stud into place with stud driver (J-6880). When driver bottoms on head, stud is at correct height.

1. Remove valve cover. Remove spark plug, rocker arm assembly and push rod of cylinder to be serviced. Install air hose and adapter in spark plug hole, and apply air pressure. Do not remove air pressure until all components are reinstalled.
2. Use valve spring compressor to compress valve spring, and retainer locks. Release spring compressor and remove spring retainer (or rotator), shield, spring, and oil seal. (Scheme 11)

Exploded View of Valve Spring Assembly. Scheme 11

Note. Damper is not used on 4.1L engines.

Install damper, spring, shield and retainer. Use compressor tool to compress valve spring, and install new oil seal and retainer locks. Remove compressor tool. Remove air hose and adapter. Install remaining components in reverse order of removal.

VALVE SPRING INSTALLED HEIGHT

Measure valve spring installed height from spring seat (or top of shim), to top of spring (or valve shield). Installed height should be 1.63-1.69" (41.4-43.0 mm). If height exceeds specifications, install a 1/16" (1.58 mm) thick shim under spring.

VALVE STEM OIL SEAL SERVICE

"O" ring-type seals are used. Lightly coat seal with engine oil and install in lower groove of valve stem. Make sure seal is not twisted in groove.

VALVE GUIDE SERVICING

Valve guides are integral with cylinder head. If guide is worn, it must be reamed for installation of valves with oversize stems. Valves are available with .003" (.08 mm), .015" (.38 mm) and .030" (.76 mm) oversize stems. Use reamers in sequence when reaming valve guides.

HYDRAULIC VALVE LIFTERS

Disassemble lifters and thoroughly clean. Inspect all components for wear and damage. If any components are worn or damaged, complete lifter assembly must be replaced. If push rod seat or lifter body wear is noted, inspect mating engine components for wear. (Scheme 12)

Cutaway View of Valve Lifter Assembly. Scheme 12

1. Drain and remove radiator. Remove drive belt(s), fan and pulley. Remove crankshaft pulley and vibration damper. Remove oil pan-to-front cover attaching bolts, then front cover-to-block attaching bolts.

Note. This engine uses RTV sealer in lieu of an oil pan front rubber seal.

1. Clean all gasket mating surfaces. Place a 3/16" bead of RTV sealer on cover-to-pan sealing surface.
2. Coat front cover gasket with sealer, and position on cover. Apply 1/8" bead of RTV sealer to joint formed by oil pan and cylinder block. Install oil seal centering tool (J-23042 or equivalent) in front cover seal and install cover to cylinder block.
3. Install and partially tighten oil pan-to-cover bolts. Install front cover-to-cylinder block bolts. Remove centering tool and tighten bolts. To install remaining components, reverse removal procedure.

Removal (Front Cover Installed)

Remove vibration damper. Pry seal out of cover with screwdriver, using care not to damage cover seal surface.

Install new seal with open end toward inside of cover. Drive seal into place using seal driver (J-23042).

Removal (Cover Removed)

Pry seal out of cover with screwdriver, using care not to damage cover seal surface.

Install new seal with open end of seal toward inside of cover. Support cover at seal recess area. Using a seal installing tool, drive seal into position.

Inspection

With engine front cover removed, check backlash between timing gear teeth. Backlash should be .004-.006" (.10-.15 mm) for new gears, and .004-.008" (.10-.20 mm) for used gears. Check both gears for runout with a dial indicator. Maximum camshaft gear runout is .004" (.10 mm). Maximum crankshaft gear runout is .003" (.08 mm).

1. Remove camshaft from engine. Position camshaft and gear on arbor press, and properly support hub of gear. Make sure thrust plate is positioned so Woodruff key in shaft will not be damaged when camshaft is pressed out of gear. Press camshaft from gear. (Scheme 13)
2. Remove crankshaft gear from crankshaft, using gear puller (J-8105 or equivalent).

Removing Camshaft from Gear. Scheme 13

Note. Properly support hub of camshaft gear, to avoid gear damage.

1. With crankshaft properly supported, use hollow driver (J-5590 or equivalent), to drive gear onto crankshaft.
2. To install camshaft gear, position camshaft in a press with camshaft supported at back of front journal. Place gear spacer ring and thrust plate over camshaft and install Woodruff key in keyway. Press gear onto camshaft until it bottoms on gear spacer ring.

1. Remove engine from vehicle. Remove valve cover and loosen all rocker arm nuts. Rotate rocker arms to side and withdraw push rods in sequence, for reinstallation in original locations.
2. Remove valve lifter side cover and remove lifters. Remove front engine cover and fuel pump. Align crankshaft and camshaft timing gear marks. Remove camshaft thrust plate bolts through access holes in camshaft gear. Carefully remove camshaft.

Coat camshaft lobes with Lubriplate (or equivalent). Reverse procedure to install camshaft, ensuring timing marks on gears are aligned. Take care to avoid damage to camshaft lobes or bearings. Install new valve lifters. Reassemble and install engine in vehicle. Change oil and oil filter. (Scheme 14)

Timing Gear Mark Alignment. Scheme 14

Note. Remove camshaft thrust plate bolts through access holes in camshaft gear.

CAMSHAFT END THRUST

Check camshaft end play with feeler gauge. End play should be.001-.005" (.03-.13 mm). (Scheme 15)

Checking Camshaft End Play. Scheme 15

Scheme 16

1. With valve cover removed, remove rocker arm assemblies. Mount dial indicator on rocker arm stud. Position dial indicator and ball socket adapter on push rod. (Scheme 16) (Scheme 16): Checking Camshaft Lobe Lift
2. Slowly rotate engine in direction of rotation until lifter is on base circle of camshaft. Zero dial indicator. Rotate engine until push rod is fully raised. Record lobe lift reading and compare with specifications. If not within limits, replace camshaft and lifters.

With engine removed from vehicle, remove camshaft, oil pan and oil pump. Drive camshaft rear plug from block. Drive camshaft bearings from engine. Remove front and rear bearings after center bearings have been removed.

Install front and rear bearings first, to act as guide for pilot of tool, and to center remaining bearings being pulled into place. Oil holes in cam bearings must align with oil holes in block. Install new camshaft rear plug.

OIL PAN

1. Disconnect negative battery cable and remove engine cover. Remove air cleaner and studs. Remove fan guard. Remove radiator upper supports. Raise vehicle.
2. On Man. Trans. models, disconnect clutch cross shaft from left front mount bracket. Remove transmission-to-bellhousing upper bolt. Remove transmission rear mount bolts and install two 7/16" x 3" bolts. Raise transmission using jack and install 2" block between mount and crossmember.
3. On all models, remove starter and drain engine oil. Remove engine mount bolts. Raise engine sufficiently to insert wooden blocks between engine mounts and crossmember brackets.
4. Remove flywheel splash shield or torque converter cover as applicable. Remove oil pan attaching bolts and remove oil pan.

1. Remove oil pan, oil pump and cylinder head. Position piston at bottom of stroke, and cover with cloth to collect metal cuttings. Remove ridge at top of cylinder bore with a ridge reamer.
2. If necessary, mark connecting rod for cylinder identifi- cation. Remove connecting rod cap nuts and cap, and cover rod bolts with rubber hose. Push piston and rod assembly out top of cylinder block.

1. Before installing piston and rod assembly, ensure ring gaps are properly spaced. (Scheme 17) Lightly coat pistons, rings and cylinder walls with engine oil. Install rod bearings in rod and cap, and lubricate with engine oil.
2. Compress piston rings with ring compressor. Do not allow position of rings to change. Cover connecting rod bolts with rubber hose. Install piston and rod assembly, with notch on top of piston facing front of engine. Install and tighten connecting rod cap.

FITTING PISTONS

1. Using telescope gauge and micrometer, measure cylinder bore diameter at a point 2 1/2" (64 mm) from top of bore. Measure piston diameter across piston skirt, at center line of piston pin. Difference between the two measurements is piston-to-cylinder bore clearance.
2. Using cylinder bore gauge, measure cylinder bore taper by working gauge up and down in bore. Measure cylinder bore out-of-round. Take measurements at different points in bore, by rotating gauge horizontally, around entire circumference of bore. Out-of-round must not exceed .002" (.05 mm). Taper must not exceed .005" .13 mm).
3. If taper or out-of-round are not within limits, hone or bore cylinders for installation of new pistons.

FITTING RINGS

1. Position ring into cylinder bore at a point about 1/4" above ring travel. Ring must be square in bore. Measure ring end gap with a feeler gauge.
2. Before installing compression rings on pistons, check side clearance. Insert outer edge of ring in its respective groove, and slide ring around entire circumference of groove. The ring should slide freely in groove.
3. Check side clearance of compression rings, with feeler gauge inserted between ring and ring groove. Install rings with gaps properly positioned. Note that anti-rotation tang of oil ring spacer is inserted into oil hole (or slot) of piston. (Scheme 17)

Desired Ring Gap Locations. Scheme 17

Using an arbor press and piston pin remover/installer tool, press piston pin from piston and connecting rod.

Check clearance of piston pin in piston, and replace piston and pin assembly if not within limits. Lubricate piston pin holes in piston and connecting rod. Position connecting rod on piston and press in piston pin, using pin remover/installer tool and an arbor press. Check piston for freedom of movement on piston pin.

Note. Following procedures are performed with oil pan and oil pump removed. Remove oil film from surfaces to be checked.

CRANKSHAFT MAIN BEARING SERVICE

Some production crankshafts are ground to .009" (.23 mm) undersize at the assembly plant. They are identified as follows

1. Crankshaft counterweight of undersize journal, will be stamped on one side with the number "9," along with a large spot of light green paint.
2. Main bearing cap will be painted light green on each side. Mark or identify main bearing cap before removing. Support crankshaft weight, using a jack placed under counterweight next to the bearing being checked. Loosen drive belts from crankshaft pulley, prior to checking No. 1 bearing. Remove main bearing cap and place a piece of Plastigage across full width of bearing, about 1/4" off center, and away from oil holes. Install cap and tighten to specifications. Do not allow crankshaft to turn. Remove cap and measure width of Plastigage with scale furnished. Standard, .001" (.03 mm) or .002" (.05 mm) undersize bearing halves may be used in combination to obtain correct clearance. Always replace both upper and lower bearing halves. With the exception of rear main bearing, main bearings are removed from cylinder block using remover/installer tool (J-8080 or equivalent). Insert tool in crankshaft oil hole and rotate crankshaft clockwise. If tool not available, a cotter pin may be bent, as necessary, to do the job. To remove rear main bearing from block, partially drive out bearing with a drift. Use a pair of pliers (with jaws taped) to hold bearing thrust surface to the oil slinger, and rotate crankshaft to remove bearing. Lubricate journal and bearings. Insert plain end of new bearing between crankshaft and notched side of block. Insert bearing remover/installer tool into crankshaft oil hole, and rotate bearing into place. To install rear main bearing, use pliers (as used in removal), to aid in installation. Install lower bearing half into cap. Install and tighten main bearing caps with arrows pointing toward front of engine. Align thrust bearing, then check crankshaft end play. Check end play by prying crankshaft forward, and inserting feeler gauge between crankshaft counterweight and forward face of rear main bearing cap.

CONNECTING ROD BEARING SERVICE

1. Ensure rod caps are marked for cylinder identification. Remove rod cap and bearings. Inspect bearings for wear or damage and replace as necessary.
2. Check crankshaft rod bearing journal for out-of-round or taper. Maximum crankshaft out-of-round or taper must not exceed .001" (.03 mm).
3. Check rod bearing clearance using the Plastigage method (as explained in Main Bearings). If clearance exceeds specifications, standard, .001" (.03 mm), or .002" (.05 mm) undersize bearings may be used in combination to produce correct clearance. If clearance is still excessive, crankshaft must be reconditioned.
4. Clean crankshaft journal and bearing surface in rod. Insert bearings in rod and cap, then lubricate bearing surfaces with oil. Pull piston and rod assembly down onto crankshaft. Install and tighten rod cap.

THRUST BEARING ALIGNMENT

Ensure all other main bearing caps have been properly tightened. Tighten rear main bearing cap to 10-12 ft. lbs. (14-16 N.m). Tap crankshaft rearward, then forward, using a lead hammer. Tighten rear main bearing cap. Retighten all main bearing caps.

Remove rear main bearing cap and pry out old seal. Remove upper half of seal by tapping end with brass punch until seal protrudes enough to be removed with pliers.

Scheme 18

1. Fabricate an oil seal installation tool, if one is not supplied with replacement oil seal. (Scheme 18) Coat seal lips with engine oil. Keep oil off of seal ends. Position tool between crank- shaft and seal groove in cylinder block. Position seal between tip of tool and crankshaft. (Scheme 18): Rear Main Oil Seal Installation Tool
2. Roll seal around crankshaft, using tool as a "shoehorn" to protect seal from sharp corner of seal groove in cylinder block. Tool must remain in position until seal is positioned with both ends flush with block.
3. Install lower seal into bearing cap, using tool as a "shoehorn". Feed seal into cap using light pressure with thumb and finger. Apply sealer to cap-to-block mating surface of cylinder block, being careful to keep sealer off the seal split line. Install and tighten bearing cap.

Disconnect negative battery cable at battery. Drain cooling system. Remove all drive belts, then remove fan and pulley from water pump. Remove lower radiator hose and heater hose from water pump. If necessary, remove alternator adjusting bracket from water pump. Remove water pump.

Clean all gasket mating surfaces. Install components in reverse order of removal procedure, using new gasket.

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

DESCRIPTION

Gear-type pump provides full pressure lubrication. Oil drawn through pick-up screen, is pressurized through pump and routed to oil filter. A bypass valve allows oil flow to main gallery in the event back pressure is encountered at filter.

Main gallery supplies oil to camshaft bearings, lifters and main bearings. Connecting rod bearings are supplied oil from crank- shaft main bearings, through cross-drilled passages.

Oil passing through hollow push rods lubricates valve train. Oil drains back to crankcase through drain holes. Timing gears are lubricated through nozzle, which is fed from front camshaft bearing. (Scheme 19)

Engine Oiling System. Scheme 19

CRANKCASE CAPACITY

Capacity is 4 quarts (3.8L) for 4.1L. Add 1 quart (.95L) when replacing oil filter.

OIL FILTER

Replace at every other oil change, or more often under severe conditions.

NORMAL OIL PRESSURE

With engine at normal operating temperature, oil pressure should be 30-40 psi (2.1-2.8 kg/cm 2 ) at 2000 RPM.

OIL PRESSURE REGULATOR VALVE

Valve in pump body is not adjustable.

Remove oil pan. Remove oil inlet tube attaching bolt and oil pump attaching bolts. Remove oil pump and tube assembly.

Disassembly

Remove oil inlet tube assembly. Remove pump cover. Mark idler gear and drive gear at a meshing point, for later reassembly of gears in same meshing position. Remove idler gear and drive gear with shaft, from pump body. Remove pressure regulator valve retaining pin, then remove spring and valve.

Oil Pump Assembly. Scheme 20

Note. If any part of oil pump requires replacement, the entire pump assembly must be replaced.

1. Clean all parts. Inspect pump body and cover for cracks and excessive wear. Inspect pump gears for damage or excessive wear. Check drive gear shaft for looseness in pump body.
2. Inspect oil inlet tube assembly for damage. Check pressure regulator valve for fit in bore.

Reassembly

Install oil inlet tube assembly. Apply sealer to end of tube, and tap tube into place, using plastic hammer. Install idler gear into pump body with smooth side of gear toward cover opening. Reassemble remaining components in reverse order of disassembly.

Prime oil pump with engine oil prior to installation. Install oil pump and pick-up tube in reverse order of removal.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL ENGINE SPECIFICATIONS

GENERAL SPECIFICATIONS

VALVE SPECIFICATIONS

VALVE SPECIFICATIONS

PISTON/PIN/RING SPECIFICATIONS

PISTONS, PINS & RINGS SPECIFICATIONS

BEARING SPECIFICATIONS

MAIN & ROD BEARINGS SPECIFICATIONS

VALVE SPRING SPECIFICATIONS

VALVE SPRINGS SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

CAMSHAFT SPECIFICATIONS

See also:
• ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION