Engine Mechanical - 8.1L (Unit Repair): Other GMC Sierra 2500

Boring Procedure

Important: The coating on the piston allows for an interference fit between the cylinder and the bore. The piston diameter can NOT be measured accurately because the piston coating is not a consistent thickness. Do NOT measure the piston diameter.

To select the correct piston for installation, the cylinder bore must be measured. If the cylinder bore diameter is within service specifications, install the original piston/connecting rod assembly or a new, standard size piston/connecting rod assembly. A used piston/connecting rod assembly may be reinstalled if, after cleaning and inspection, the piston is not damaged. If the cylinder bore is NOT within specifications, the cylinder must be resized to accept a new, oversized piston.

Important: If you do not check the cylinder block, the boring bar may be tilted, this may result in incorrect rebored cylinder wall to crankshaft angle.

1. Before you use any type of boring bar, clean the top of the cylinder block in order to remove any dirt or burrs.
2. Carefully follow the instructions furnished by the manufacturer regarding use of equipment.
3. When you rebore cylinders, make sure all crankshaft bearing caps are in place. Tighten the bearing caps to the proper torque in order to avoid distortion of the bores in the final assembly. The crankshaft must be removed prior to cylinder boring.
4. When you take the final cut with a boring bar, leave 0.03 mm (0.001 in) on the diameter for finish honing. This gives the required position to the cylinder clearance specifications. (Carefully perform the honing and boring operation in order to maintain the specified clearances between pistons, rings, and cylinder bores).

Honing Procedure

Important: Always remove all bearings and components from engine block before cleaning, boring or honing the engine block.

1. When honing the cylinders, follow the manufacturer's recommendations for equipment use, cleaning, and lubrication. Use only clean, sharp stones of the proper grade for the amount of material you remove. Dull, dirty stones cut unevenly and generate excessive heat. Do not hone to a final grade with a coarse or medium-grade stone. Leave sufficient metal so that all stone marks may be removed with fine grade stones. The re-honed surface finish should be 0.25-0.50 micrometer (10-20 microinch). Perform final honing with a fine-grade stone and hone the cylinder in a cross hatch pattern at 20 to 30 degrees to obtain the proper clearance.
2. During the honing operation, thoroughly clean the cylinder bore. Repeatedly check the cylinder bore for fit with the selected oversized piston. All measurements of the cylinder bore should be made with the components at normal room temperature.
3. To eliminate taper in the cylinder, when honing, make full strokes of the hone in the cylinder. Repeatedly check the measurement at the top, the middle, and the bottom of the bore. The finish marks should be clean but not sharp. The finish marks should be free from embedded particles and torn or folded metal.
4. When finished, the reconditioned cylinder bores should have less than or meet the specified out-of-round or taper requirements.
5. After final honing and before the piston is checked for fit, clean the bores with hot water and detergent. 5.1. Scrub the bores with a stiff bristle brush and rinse the bores thoroughly with hot water. Do not allow any abrasive material to remain in the cylinder bores. Abrasive material may cause premature wear of new piston rings and cylinder bores. Abrasive material will contaminate the engine oil and may cause premature wear of the bearings. 5.2. After washing the cylinder bore, dry the bore with a clean shop towel.
6. Perform final measurements of the cylinder bore.
7. Permanently mark the piston for the specific cylinder to which it has been fitted.
8. Apply clean engine oil to each cylinder bore in order to prevent rusting.

Crankshaft and Connecting Rod Bearing Clearance Measurement

The crankshaft and connecting rod bearings are of the precision insert type and do not use shims for adjustment.

Crankshafts with journals that measure less than minimum specifications must be replaced.

Micrometer Method for Crankshaft Bearings

Important: When bearings are removed, NEW bearings must be installed during reassembly.

Scheme 1436

Scheme 1437

1. Measure the crankshaft main journal diameter with a micrometer in several places along the length approximately 90 degrees apart, minimum of 4 places, and average the measurements.
2. Determine the taper and the out-of-round. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
3. Install the NEW crankshaft bearings into the crankshaft bearing caps and the engine block. Important: Tighten the inner crankshaft bearing cap bolts before tightening the outer crankshaft bearing cap studs.
4. Install the crankshaft bearing caps and the crankshaft bearing cap bolts and studs. 4.1. Tighten the crankshaft bearing cap inner bolts to 30 N.m (22 lb ft). 4.2. Tighten the crankshaft bearing cap outer studs to 30 N.m (22 lb ft). 4.3. Using J 36660-A , tighten the crankshaft bearing cap inner bolts an additional 90 degrees. 4.4. Using J 36660-A , tighten the crankshaft bearing cap outer studs an additional 80 degrees.
5. Measure the crankshaft bearing inside diameter (ID) using an inside micrometer. Measure at a minimum of four places and average the measurements.
6. In order to determine the crankshaft bearing clearance, subtract the crankshaft journal diameter from the crankshaft bearing ID.
7. Compare the crankshaft bearing clearance to the specifications. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
8. If the crankshaft bearing clearances exceeds specifications, install undersize crankshaft bearings to achieve the correct clearance.
9. Measure the new crankshaft bearing inside diameter (ID) using an inside micrometer.
10. Replace the crankshaft if the proper clearances cannot be obtained with standard size bearings.

Micrometer Method for Connecting Rod Bearings

Important: When bearings are removed, NEW bearings must be installed during reassembly.

Scheme 1438

1. Measure the crankpin diameter with a micrometer in several places along the length, approximately 90 degrees apart, minimum of 4 places, and average the measurements.
2. Determine the taper and the out-of-round. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
3. Install the NEW connecting rod bearings into the connecting rod cap and the connecting rod. Important: Use the original connecting rod nuts for clearance measurement. During final assembly new connecting rod nuts must be used to obtain correct fastener tightening.
4. Install the connecting rod cap and the original, used, nuts. Tighten the connecting rod nuts to 30 N.m (22 lb ft). Tighten the connecting rod nuts an additional 90 degrees.
5. Measure the connecting rod bearing inside diameter (ID) using an inside micrometer.
6. Compare the connecting rod bearing clearance specifications. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
7. If the connecting rod bearing clearances exceed specifications, replace components as required.

Plastic Gage Method for Crankshaft Bearings

Important: When bearings are removed, NEW bearings must be installed during reassembly.

Scheme 1439

1. Install the crankshaft and the new crankshaft bearings into the block, making sure not to damage the reluctor rings of the crankshaft.
2. Install the gaging plastic the full width of the crankshaft journal. Important: Tighten the inner crankshaft bearing cap bolts before tightening the outer crankshaft bearing cap studs. The crankshaft journal and the crankshaft bearing surface must be free from oil to obtain a correct measurement. Do not allow the crankshaft to rotate while performing the measurement, or an incorrect measurement will be obtained.
3. Install the crankshaft bearing caps and the crankshaft bearing cap bolts and studs. 3.1. Tighten the crankshaft bearing cap inner bolts to 30 N.m (22 lb ft). 3.2. Tighten the crankshaft bearing cap outer studs to 30 N.m (22 lb ft). 3.3. Using J 36660-A , tighten the crankshaft bearing cap inner bolts an additional 90 degrees. 3.4. Using J 36660-A , tighten the crankshaft bearing cap outer studs an additional 80 degrees.
4. Remove the crankshaft bearing cap bolts and the crankshaft bearing caps. The gaging plastic may adhere to either the crankshaft journal or the crankshaft bearing surfaces.
5. On the edge of the gaging plastic envelope there is a graduated scale. Without removing the gaging plastic, measure the compressed width at the widest point.
6. If the flattened gaging plastic tapers toward the middle or the ends, there may be a difference in clearance indicating taper, low spot or other irregularity of the crankshaft bearing or the crankshaft journal. Normally the crankshaft journals wear evenly and are not out-of-round. However, if a crankshaft bearing is being fitted to an out-of-round 0.0254 mm (0.001 in maximum) crankshaft journal, be sure to fit to the maximum diameter of the crankshaft journal. If the crankshaft bearing is fitted to the minimum diameter and the crankshaft journal is excessively out-of-round, the interference between the crankshaft bearing and the crankshaft journal will result in rapid crankshaft bearing failure.
7. Compare the crankshaft bearing clearance to the specifications. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
8. If the crankshaft bearing clearances exceeds specifications, replace components as required.
9. Measure the new crankshaft bearing inside diameter (ID) using the same method.
10. Replace the crankshaft if the proper clearances cannot be obtained with standard size bearings.
11. Remove the flattened gaging plastic.
12. Measure the remaining crankshaft journals.

Plastic Gage Method for Connecting Rod Bearings

Important: When bearings are removed, NEW bearings must be installed during reassembly.

Scheme 1440

1. Install the connecting rod bearings (4) into the connecting rod (3) and the connecting rod cap (5).
2. Using rubber fuel line over the connecting rod bolts, install the piston and connecting rod assembly onto the crankpin journal.
3. Install the gaging plastic the full width of the crankpin journal. Important: Use the original connecting rod nuts for clearance measurement. During final assembly, new connecting rod nuts must be used to obtain correct fastener tightening.
4. Install the connecting rod cap and the original, used, nuts. Tighten the connecting rod nuts to 30 N.m (22 lb ft). Tighten the connecting rod nuts an additional 90 degrees.
5. Remove the connecting rod nuts and cap. The gaging plastic may adhere to either the crankpin journal or the connecting rod bearing surface.
6. On the edge of the gaging plastic envelope there is a graduated scale. Without removing the gaging plastic, measure the compressed width at the widest point. If the flattened gaging plastic tapers toward the middle or the ends, there may be a difference in clearance indicating taper, low spot or other irregularity of the crankshaft bearing or the crankpin journal.
7. Normally the crankpin journals wear evenly and are not out-of-round. However, if a connecting rod bearing is being fitted to an out-of-round 0.0254 mm (0.001 in maximum) crankpin journal, be sure to fit to the maximum diameter of the crankpin journal. If the connecting rod bearing is fitted to the minimum diameter and the crankpin journal is excessively out-of-round, the interference between the connecting rod bearing and the crankpin journal will result in rapid connecting rod bearing failure.
8. Compare the connecting rod bearing clearance to the specifications. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
9. If the connecting rod bearing clearances exceed specifications, replace components as required.
10. Remove the flattened gaging plastic.
11. Measure the remaining crankpin journals.

Measuring Crankshaft End Play

Important: In order to properly measure the crankshaft end play, the crankshaft, bearings, bearing caps and fasteners must be installed into the engine block and the bolts tightened to specifications. Refer to Crankshaft & Bearings Installation .

Scheme 1441

1. Install the J 7872 or equivalent to the cylinder block, with the dial indicator plunger against one of the counterweights of the crankshaft.
2. Firmly thrust the end of the crankshaft first rearward then forward. This will line up the rear crankshaft bearing and the crankshaft thrust surfaces.
3. With the crankshaft pushed forward, zero the dial indicator. Move the crankshaft rearward and read the end play measurement on the dial indicator. An optional method is to insert a feeler gage between the crankshaft and the bearing surface and measure the clearance. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
4. If the correct end play cannot be obtained, inspect the crankshaft thrust wall surface or surfaces for wear and/or excessive runout.
5. Inspect the crankshaft for binding. Turn the crankshaft to check for binding. If the crankshaft does not turn freely, loosen the crankshaft bearing bolts and studs, one cap at a time, until the tight bearing is located. The following condition or conditions could cause a lack of clearance at the bearing: Burrs on the crankshaft bearing cap Foreign matter between the crankshaft bearing and the block or the crankshaft bearing cap A faulty crankshaft bearing

Measuring Connecting Rod Side Clearance

Important: In order to properly measure the connecting rod side clearance, the piston/connecting rod assembly and bearings must be installed into the engine block and the connecting rod nuts tightened to specifications. Refer to Piston, Connecting Rod & Bearing Installation .

Scheme 1442

1. Install the J 7872 or equivalent to the cylinder block, with the dial indicator plunger against the side of the pair of connecting rods.
2. With the connecting rods pushed forward, zero the dial indicator. Firmly move the pair of connecting rods side to side and read the measurement on the dial indicator. An optional method is to insert a feeler gage between the connecting rod caps and measure the connecting rod side clearance. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .

Scheme 1443

1. Clean the crankshaft balancer in solvent.
2. Dry the crankshaft balancer with compressed air.
3. Inspect the crankshaft balancer for the following: Damaged belt grooves (3) Debris in the belt grooves (3) Worn, grooved, or damaged hub seal surface (1) Minor imperfections on the hub seal surface may be removed with a polishing compound or fine grade of emery cloth. A crankshaft balancer hub seal surface with excessive scoring, grooves, rust or other damage must be replaced. Worn, chunking or deteriorated rubber between the hub and pulley (2)
4. Repair or replace the crankshaft balancer as necessary.

Scheme 1444

1. Clean the engine flywheel in solvent.
2. Dry the engine flywheel with compressed air.
3. Inspect the engine flywheel for the following conditions: Stress cracks around the engine flywheel-to-torque converter mounting bolt hole locations (1) and/or engine flywheel-to-crankshaft (2, 3) Important: Do not attempt to repair the welded areas that retain the ring gear to the engine flywheel plate. Install a new engine flywheel. Cracks at welded areas that retain the ring gear onto the engine flywheel (4) Damaged or missing ring gear teeth (5)

Scheme 1445

1. Clean the engine flywheel in solvent.
2. Dry the engine flywheel with compressed air.
3. Inspect the manual transmission engine flywheel for the following conditions: Pitted surface (1) Scoring or grooves (2) Rust or other surface damage (3) Damaged ring gear teeth (4) Loose or improperly positioned ring gear The ring gear has an interference fit onto the engine flywheel and should be positioned completely against the flange of the engine flywheel.

Cleaning Procedure

Important: Mark, sort, or organize components for return to their original locations.

Scheme 1446

Scheme 1447

1. Clean the valve stems and heads on a buffing wheel.
2. Clean the following components in solvent: Valve stem keys (1) Valve spring cap (2) Valve spring (3) Valve Rotators (5) Valve (6) Cylinder head
3. Dry the components with compressed air. Important: Be careful not to damage the chamber or the valve seat.
4. Use the J 8089 in order to clean the carbon from the combustion chambers.

Flatness Measurement Procedure

1. Measure the cylinder head for warpage with a straight edge and feeler gage. A cylinder head block deck with warpage in excess of 0.050 mm (0.002 in) within a 150.0 mm (6.0 in) area must be repaired or replaced. A cylinder head exhaust manifold deck with an overall warpage in excess of 0.102 mm (0.004 in) must be repaired or replaced. A cylinder head intake manifold deck with warpage in excess of 0.080 mm (0.003 in) must be repaired or replaced.
2. A cylinder head block deck can be resurfaced up to 0.305 mm (0.012 in) maximum removal. Important: Excessive cylinder head resurfacing will affect compression ratio and emission control.
3. A cylinder head that requires excessive resurfacing must be replaced.

Scheme 1448

1. Inspect the valves for the following conditions: Burnt or damaged areas (1) Undersized valve margin (2) Bent stem (3) Scoring or other damage to the stem (4) Worn key groove (5) Worn stem tip (6)
2. Inspect the valve contact surface for the following conditions: Undersized margin (1) Pitted surface (2) Burnt or eroded areas (3) Acceptable edge, margin (4) Important: Minor imperfections of the valve may be corrected during reconditioning.
3. Valves with excessive damage must be replaced.

Scheme 1449

1. Inspect the valve springs for broken coils or coil ends.
2. Use the J 9666 in order to measure the valve spring force. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) . Important: Add a maximum of one shim up to 0.726 mm (0.030 in) thick to increase tension.
3. If the valve spring tension is low, use a shim to increase tension.
4. Recheck the valve spring tension, a valve spring that does not meet specification must be replaced.

Valve Guide Measurement Procedure

Important: Excessive valve stem-to-guide clearance may cause an excessive oil consumption and may also cause a valve to break. Insufficient clearance will result in noisy and sticky functioning of the valve and will disturb the engine assembly smoothness.

Scheme 1450

1. Measure the valve stem-to-guide clearance. 1.1. Clamp the J 8001 on the exhaust port side of the cylinder head. Important: The indicator stem must contract the side of the valve stem just above the valve guide. 1.2. Locate the indicator so that the movement of the valve stem from side to side, crosswise to the cylinder head, will cause a direct movement of the indicator stem. 1.3. Drop the valve head about 1.6 mm (0.064 in) off the valve seat. 1.4. Use light pressure when moving the valve stem from side to side in order to obtain a clearance reading. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) .
2. Valve guide (2) with excessive clearance must be repaired. Refer to «Valve Guide Reaming/Valve & Seat Grinding»(ref-176274-S40729054662005050500000) .
3. Replace the cylinder head if the valve guide cannot be repaired or reamed to accept an oversize valve stem.

Valve Guide Reaming Procedure for Oversized Valve Stems

Note. The exhaust valve guides are replaceable components and must be serviced properly. The exhaust valve guide must be pressed out and into the cylinder head in the proper directions. The old exhaust valve guide must be removed by pressing out towards the combustion chamber side of the cylinder head. The new exhaust valve guide must be installed by pressing from the combustion chamber side of the cylinder head. Failure to press the exhaust valve guide out and into the cylinder head in the proper directions will damage the cylinder head.

Scheme 1451

1. Ream the valve guide as necessary to achieve proper valve stem-to-guide clearance with the new, oversized valve stems.
2. Always recondition the valve seat after reaming the valve guide bores or installing new valves.
3. Replace the cylinder head if the valve guide cannot be repaired or reamed to accept an oversize valve stem.

Scheme 1452

1. Replace the valve if the valve stem shows excessive wear or is warped. Important: Several different types of equipment are available for reconditioning valves. Use the manufacturers recommendations of equipment to attain the proper results.
2. Reface pitted valves on a valve refacing machine in order to insure the correct relationship between the head and the stem.
3. Replace the valve if the edge of the head is less than 0.79 mm (0.031 in) thick after grinding.

Valve Seat Reconditioning Procedure

Important: Several different types of equipment are available for reconditioning valve seats. Use the manufacturers recommendations of equipment to attain the proper results.

Important: Always recondition the valve seat after reaming the valve guide bores or installing new valves.

Scheme 1453

1. Recondition the valve seats.
2. The valves must seat perfectly for the engine to deliver optimum power and performance.
3. Ensure that the valve seat and valve are not shrouded after valve seat reconditioning. Adequate flow past the valve seat and valve is essential for cooling the valve head and valve seat area.
4. Correct contact (1) between each valve and its seat in the cylinder head is also essential to ensure that the heat in the valve head is properly carried away. Important: Regardless of what type of equipment is used, it is essential that the valve guide bores are free from carbon or dirt to ensure the proper centering of the pilot in the guide.
5. The valve seats should be concentric to within 0.050 mm (0.002 in) total indicator runout.

Checking Valve Spring Installed Height

1. Install the valve rotator (3), the valve (4), the valve spring cap (1) and the valve stem keys (5) into the cylinder head.
2. Using a snap gage or inside micrometer, measure the distance from the top of the valve rotator to the bottom of the valve spring cap. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) for proper valve spring installed height specifications. Important: Never shim the spring to obtain an installed height under the specified amount. Install the valve spring seat shims under the rotator, between the rotator and the cylinder head spring seat. Add a maximum of one valve spring seat shim, up to 0.726 mm (0.030 in) thick to achieve the valve spring installed height specification. The combination of valve spring seat shims to correct valve spring installed height and valve spring tension should not exceed 1.524 mm (0.060 in) thick.
3. Install a valve spring seat shim if the valve spring installed height measurement is above the specification.
4. Recheck the valve spring installed height, replace the cylinder head if the valve spring installed height cannot be obtained.

Thread Repair

Tools Required

J 39345 Thread Repair Kit

The following procedure is used to accomplish proper and durable thread repairs in the cylinder head and the cylinder block, using the J 39345 .

Important: Take appropriate precautions to assure that machining chips will not remain inside the engine. For example, block all intake passages, oil drain back holes and exhaust passages with a towel or tape before performing thread repairs.

1. Select the proper size drill as indicated in the schematic charts found in Thread Repair Specifications for the hole being repaired.
2. Drill out the damaged threads to the original depth or completely through for through holes.
3. Apply compressed air with a shop towel wrapped around the air spout, in order to retain the chips forced out of the hole.
4. Select the correct size tap, using the appropriate chart for the hole being repaired.
5. Coat the tap and the hole with spray machining oil.
6. Tap the hole to the original depth. In order to clean the threads, reverse the rotation of the tap periodically.
7. Use solvent to clean out all of the chips.
8. Apply compressed air with a shop towel wrapped around the air spout, in order to retain the chips forced out of the hole.
9. Tap the hole again to clean the threads. The tap should thread in with little resistance. Important: Make sure all of the chips are cleared from the hole.
10. Use solvent to clean out all of the chips.
11. Apply compressed air with a shop towel wrapped around the air spout, in order to retain the chips forced out of the hole.
12. Use a flashlight to confirm that all of the chips are removed from the hole.
13. Continue to clean the hole until all of the chips are cleared.
14. Install the heli-coil insert as follows: 14.1. In order to determine the correct size installation tool and length insert, refer to the appropriate picture and chart. 14.2. Screw the insert on the mandrel of the installation tool until the driving tang is fully engaged in the driving contour. 14.3. Coat the insert with spray machining oil. 14.4. Install the insert as follows: 14.4.1. Slide the prewinder over the mandrel and insert. 14.4.2. Rotate the mandrel clockwise until 1 or 2 threads of the insert are threaded into the prewinder. 14.4.3. Place the insert in position on the threaded hole being repaired. 14.4.4. Rotate the mandrel clockwise until the insert is flush with the top surface of the threaded hole. 14.4.5. Remove the prewinder except when repairing cylinder head bolts. 14.4.6. Continue to install the insert until reaching the original thread depth. 14.4.7. Remove the mandrel. 14.5. Remove the driving tang from the thread insert as follows. The tang must be removed in order to allow passage of the fastener through the insert. 14.5.1. Place the square end of the punch, no chamfer, on the tang after installation. 14.5.2. Strike the punch sharply with the hammer. The tang will break off at the notch.
15. Clean the hole using compressed air. Take appropriate steps to assure that chips are not blown into the engine.

Piston Selection

Important: The coating on the piston allows for an interference fit between the cylinder and the bore. The piston diameter can NOT be measured accurately because the piston coating is not a consistent thickness. Do NOT measure the piston diameter.

To select the correct piston for installation, the cylinder bore must be measured. If the cylinder bore diameter is within service specifications, install the original piston/connecting rod assembly or a new, standard size piston/connecting rod assembly. A used piston/connecting rod assembly may be reinstalled if, after cleaning and inspection, the piston is not damaged. If the cylinder bore is NOT within specifications, the cylinder must be resized to accept a new, oversized piston.

Scheme 1454

For proper piston fit, the engine block cylinder bores should not have excessive wear or taper.

1. Inspect the engine block cylinder bore. Refer to «Engine Block Cleaning & Inspection»(ref-176274-S36976474222005050500000) .
2. Inspect the piston/connecting rod assembly for damage. Refer to «Piston, Connecting Rod & Bearings Cleaning & Inspection»(ref-176274-S32445105382005050500000) .
3. Use the J 8087 and measure the cylinder bore diameter. Refer to «Engine Block Cleaning & Inspection»(ref-176274-S36976474222005050500000) .
4. Measure the J 8087 with a micrometer and record the reading.
5. Compare the cylinder bore measurement to the specifications. Refer to «Engine Mechanical Specifications»(ref-176274-S07520821322005050500000) . 5.1. If the cylinder bore is within specifications, select the original piston or a new, original size piston. 5.2. If the cylinder bore is not within specifications, select the next oversized piston/connecting rod assembly, then bore and hone the cylinder bore to fit the oversize piston.

Scheme 1455

Scheme 1456

Scheme 1457

Scheme 1458

1. Coat the following components with clean engine oil: The piston The piston rings The cylinder bore The bearing surfaces
2. Install rubber fuel line onto the connecting rod bolts. Important: The mark on the top of the piston must face the front of the engine block. When assembled, the flanges on the connecting rod and cap should face to the front of block on the left bank and to the rear of block on the right bank.
3. Install the piston, connecting rod and upper connecting rod bearing through the top of the engine block.
4. Install the J 8037 onto the piston and compress the piston rings.
5. Use the J 8037 and lightly tap the top of the piston with a wooden hammer handle.
6. Hold the J 8037 firmly against the engine block until all of the piston rings have entered the cylinder bore.
7. Use the rubber fuel line in order to guide the connecting rod onto the crankshaft journal.
8. Remove the rubber fuel line.
9. Install the connecting rod cap and lower connecting rod bearing. Important: When installing the piston/connecting rod assembly, NEW connecting rod nuts must be installed.
10. Install the new connecting rod nuts. Tighten the connecting rod nuts to 30 N.m (22 lb ft) plus an additional 90 degrees.
11. Once the piston and connecting rod assemblies have been installed, lightly tap each connecting rod assembly, parallel to the crankpin, in order to make sure that they have side clearance.
12. Use a feeler gage or a dial indicator to measure the side clearance between the connecting rod caps. The rod side clearance should be 0.384-0.686 mm (0.0151-0.0270 in).

Scheme 1459

1. Lubricate the following components with clean engine oil, engine oil supplement GM P/N 1052367, (Canadian P/N 992869), or equivalent: The camshaft lobes The camshaft bearing journals The camshaft bearings NOTE: All camshaft journals are the same diameter, so care must be used in removing or installing the camshaft to avoid damage to the camshaft bearings.
2. Install the three 8-1.25 x 100 mm bolts in the camshaft front bolt holes.
3. Using the bolts as a handle, install the camshaft.
4. Remove the three bolts from the front of the camshaft.
5. Install the camshaft retainer.
6. Install the camshaft retainer bolts. Tighten the camshaft retainer bolts to 12 N.m (106 lb in).

Cylinder Block

The engine block is made of cast iron and it has eight cylinders arranged in a V shape with four cylinders in each bank. The engine block is a one piece casting with the cylinders encircled by coolant jackets.

Cylinder Head

The cylinder heads are made of cast iron and have parent metal intake valve guides and intake valve seats. The cast iron exhaust valve guides and powdered metal valve seats are pressed into the exhaust ports. A spark plug is located between the valves in the side of the cylinder head. The water crossover pipe attaches to the front of each cylinder head.

Camshaft

A steel camshaft is supported by five bearings pressed into the engine block. The camshaft sprocket is mounted to the front of the camshaft and is driven by the crankshaft sprocket through a camshaft timing chain.

Motion from the camshaft is transmitted to the valves by hydraulic roller valve lifters, valve push rods, and ball-pivot type rocker arms. A spiral gear machined into the camshaft near the rear journal drives a shaft assembly which operates the oil pump driveshaft assembly. Ignition synchronization with the camshaft is provided by a physical feature integral with the camshaft sprocket.

Crankshaft

The crankshaft is made of cast nodular iron. The crankshaft is supported by five crankshaft bearings. The crankshaft bearings are retained by the crankshaft bearing caps. The crankshaft bearing caps are machined with the engine block for proper alignment and clearance. The crankshaft bearing caps are retained by two bolts and two studs each. The number five crankshaft bearing at the rear of the engine block is the end thrust bearing. The four connecting rod journals (two rods per journal) are spaced 90 degrees apart. The crankshaft position sensor reluctor ring is pushed onto the rear of the crankshaft. The crankshaft position sensor reluctor is constructed of powdered metal. The reluctor ring has an interference fit onto the crankshaft and an internal keyway for correct positioning.

Pistons and Connecting Rods

The pistons are cast aluminum alloy that use two compression rings and one oil control ring assembly. The piston pins are a floating fit in the pistons and the piston pins are retained by a press fit in the connecting rod assembly. The pistons are coated in order to create an interference fit into the cylinder. The connecting rods are forged steel and have precision insert type crankpin bearings. The piston and connecting rod is only serviced as an assembly.

Valve Train

The valve train is a ball pivot type. Motion is transmitted from the camshaft through the hydraulic roller valve lifters and tubular valve push rods to the valve rocker arms. The valve rocker arm pivots on a ball in order to open the valve. The hydraulic roller valve lifters keep all parts of the valve train in constant contact. Each valve lifter acts as an automatic adjuster and maintains zero lash in the valve train. This eliminates the need for periodic valve adjustment. The valve rocker arm stud and nut retains the valve rocker arm and ball seat. The valve rocker arm stud is threaded into the cylinder head. The valve stem seal is pressed over the valve guide of the cylinder head.

Intake Manifold

The intake manifold is a one-piece design. The intake manifold is made of cast aluminum. The throttle body is attached to the front of the intake manifold. A linear exhaust gas recirculation (EGR) port is cast into the manifold for exhaust gas recirculation mixture. The EGR valve bolts onto the rear of the intake manifold. The fuel rail assembly with eight separate fuel injectors is retained to the intake manifold by four studs. The fuel injectors are seated in their individual manifold bores with O-ring seals to provide sealing. A Manifold Absolute Pressure (MAP) sensor is mounted on the top of the intake manifold and sealed by an O-ring seal. The MAP sensor is held in place with a retainer bolt. The evaporative emission canister solenoid is located in the front of the intake manifold. The positive crankcase ventilation (PCV) system is internally cast into the intake manifold. There is not a PCV valve. A splash shield is installed under the intake manifold. The shield prevents hot oil from contacting the bottom of the intake manifold, maintaining air inlet charge density.

Exhaust Manifold

The two exhaust manifolds are constructed of cast stainless steel. The exhaust manifolds direct exhaust gases from the combustion chambers to the exhaust system. The right exhaust manifold has a flange for the EGR pipe.

New Product Information

The purpose of New Product Information is to highlight important technical changes from the previous model year.

Changes may include one or more of the following items

1. Torque values and/or fastener tightening strategies
2. Changed engine specifications
3. New sealants and/or adhesives
4. Disassembly and assembly procedure revisions
5. Engine mechanical diagnostic procedure revisions
6. New special tools required
7. A component comparison from the previous year

New Sealants And/Or Adhesives

No sealant or adhesive changes from the previous year. Refer to Sealers, Adhesives & Lubricants .

A Component Comparison from the Previous Year

The A.I.R. system has been removed from the engine. Refer to Disassembled Views .

Scheme 1460

The gear-type oil pump is driven through an extension driveshaft. The extension driveshaft is driven by the oil pump drive, which is gear driven by the camshaft. The oil is drawn from the oil pan through a pickup screen and tube, into the oil pump (7). Pressurized oil flows through the oil filter, into the oil cooler (5), back into the engine (6), up to the oil pressure gage port (2) and rear crankshaft bearing, and is then distributed to the upper oil galleries. Oil must flow around the oil pump drive (1) in order to reach the right side valve lifters properly. The oil is delivered through internal passages in order to lubricate camshaft and crankshaft bearings and to provide lash control in the hydraulic valve lifters. Oil is metered from the valve lifters through the valve push rods in order to lubricate the valve rocker arms and ball pivots. Oil returning to the oil pan from the cylinder heads and the front camshaft bearing, lubricates the camshaft timing chain and the crankshaft and the camshaft sprockets. There are two bypass valves located in the engine block, above the oil filter. The oil filter bypass valve (4) and the oil cooler bypass valve (3).

Scheme 1461

If the oil filter becomes plugged, the pressurized oil is diverted around the top of the oil filter. The oil filter bypass valve (1) is forced open, allowing the oil to continue on to the oil cooler and engine oil passages. No oil filtration occurs because the oil is not allowed into the oil filter.

Scheme 1462

If the oil cooler flow becomes blocked, either from a plugged oil cooler or blocked or kinked oil cooler line, the oil cooler bypass valve (1) is forced open, allowing oil to flow directly into the engine oil passages. Oil does not flow into or out of the engine oil cooler.

Scheme 1463

If both the oil filter and the oil cooler are plugged, the pressurized oil is routed around the top of the oil filter, through the oil filter bypass valve (2), through the oil cooler bypass valve (1) and directly into the engine oil passages. Lubrication still occurs, but the oil is not filtered or directed through the oil cooler.

Separating Parts

Important: Many internal engine components will develop specific wear patterns on their friction surfaces.

When disassembling the engine, internal components MUST be separated, marked or organized in a way to ensure reinstallation to original location and position.

Separate, mark, or organize the following components

1. Piston to the specific cylinder bore
2. Piston rings to the piston
3. Connecting rod to the crankshaft journal
4. Connecting rod to the bearing cap
5. Crankshaft and connecting rod bearings
6. Camshaft and valve lifters
7. Valve lifters, guides, pushrods, pivot supports and rocker arms
8. Valve to the valve guide
9. Valve spring and shim to the cylinder head location
10. Engine block crankshaft bearing cap location and direction
11. Oil pump drive and driven gears

Cleanliness & Care

1. Throughout this section, it should be understood that proper cleaning and protection of machined surfaces and friction areas is part of the repair procedure. This is considered standard shop practice even if not specifically stated.
2. When any internal engine parts are serviced, care and cleanliness is important.
3. When components are removed for service, they should be marked, organized or retained in a specific order for reassembly.
4. At the time of installation, components should be installed in the same location and with the same mating surface as when removed.
5. An automobile engine is a combination of many machined, honed, polished and lapped surfaces with tolerances that are measured in millimeters or thousandths of an inch. These surfaces should be covered or protected to avoid component damage.
6. A liberal coating of clean engine oil should be applied to friction areas during assembly.
7. Proper lubrication will protect and lubricate friction surfaces during initial operation.

Gasket Reuse & Applying Sealant

1. Do not reuse any gasket unless specified.
2. Gaskets that can be reused will be identified in the service procedure.
3. Do not apply sealant to any gasket or sealing surface unless specified in the service procedure.

Separating Components

1. Use a rubber mallet in order to separate the components.
2. Bump the part sideways in order to loosen the components.
3. Bumping of the component should be done at bends or reinforced areas of the component to prevent distortion of the components.

Cleaning Gasket Surfaces

1. Use care to avoid gouging or scraping the sealing surfaces.
2. Use a plastic or wood scraper in order to remove all the sealant from the components. Do not use any other method or technique to remove the sealant or the gasket material from a part.
3. Do not use abrasive pads, sand paper, or power tools to clean the gasket surfaces. These methods of cleaning can cause damage to the component sealing surfaces. Abrasive pads also produce a fine grit that the oil filter cannot remove from the engine oil. This fine grit is an abrasive and can cause internal engine damage.

Sealant Types

Important: The correct sealant and amount of sealant must be used in the proper location to prevent oil leaks, coolant leaks, or the loosening of the fasteners. DO NOT interchange the sealants. Use only the sealant (or equivalent) as specified in the service procedure.

The following 2 major types of sealant are commonly used in engines

1. Aerobic sealant (Room Temperature Vulcanizing (RTV))
2. Anaerobic sealant, which include the following: Gasket eliminator Pipe Threadlock

Aerobic Type Room Temperature Vulcanizing (RTV) Sealant

Aerobic type Room Temperature Vulcanizing (RTV) sealant cures when exposed to air. This type of sealant is used where 2 components (such as the intake manifold and the engine block) are assembled together.

Use the following information when using RTV sealant

1. Do not use RTV sealant in areas where extreme temperatures are expected. These areas include: The exhaust manifold The head gasket Any other surfaces where a different type of sealant is specified in the service procedure
2. Always follow all the safety recommendations and the directions that are on the RTV sealant container.
3. Use a plastic or wood scraper in order to remove all the RTV sealant from the plastic and aluminum components.

Important: Do not allow the RTV sealant to enter any blind threaded holes, as it may prevent the fasteners from clamping properly or cause damage when the fastener is tightened.

1. The surfaces to be sealed must be clean and dry.
2. Use a RTV sealant bead size as specified in the service procedure.
3. Apply the RTV sealant bead to the inside of any bolt holes areas.
4. Assemble the components while the RTV sealant is still wet to the touch (within 3 minutes). Do not wait for the RTV sealant to skin over.
5. Tighten the fasteners in sequence (if specified) and to the proper torque specifications. DO NOT overtighten the fasteners.

Anaerobic Type Gasket Eliminator Sealant

Anaerobic type gasket eliminator sealant cures in the absence of air. This type of sealant is used where 2 rigid parts (such as castings) are assembled together. When 2 rigid parts are disassembled and no sealant or gasket is readily noticeable, then the 2 parts were probably assembled using an anaerobic type gasket eliminator sealant.

Use the following information when using gasket eliminator sealant

1. Always follow all the safety recommendations and directions that are on the gasket eliminator sealant container.
2. Apply a continuous bead of gasket eliminator sealant to one flange.

The surfaces to be sealed must be clean and dry.

Important: Do not allow the gasket eliminator sealant to enter any blind threaded holes, as the gasket eliminator sealant may prevent the fasteners from clamping properly, seating properly, or cause damage when the fastener tightened.

1. Apply the gasket eliminator sealant evenly to get a uniform thickness of the gasket eliminator sealant on the sealing surface.

Important: Gasket eliminator sealed joint fasteners that are partially torqued and the gasket eliminator sealant allowed to cure more than five minutes, may result in incorrect shimming and sealing of the joint.

1. Tighten the fasteners in sequence (if specified) and to the proper torque specifications. DO NOT overtighten the fasteners.
2. After properly tightening the fasteners, remove the excess gasket eliminator sealant from the outside of the joint.

Anaerobic Type Threadlock Sealant

Anaerobic type threadlock sealant cures in the absence of air. This type of sealant is used for threadlocking and sealing of bolts, fittings, nuts, and studs. This type of sealant cures only when confined between 2 close fitting metal surfaces.

Use the following information when using threadlock sealant

1. Always follow all safety recommendations and directions that are on the threadlock sealant container.
2. The threaded surfaces to be sealed must be clean and dry.
3. Apply the threadlock sealant as specified on the threadlock sealant container.

Important: Fasteners that are partially torqued and then the threadlock sealant allowed to cure more than five minutes, may result in incorrect clamp load of assembled components.

1. Tighten the fasteners in sequence (if specified) and to the proper torque specifications. DO NOT overtighten the fasteners.

Anaerobic Type Pipe Sealant

Anaerobic type pipe sealant cures in the absence of air and remains pliable when cured. This type of sealant is used where 2 parts are assembled together and require a leak proof joint.

Use the following information when using pipe sealant

1. Do not use pipe sealant in areas where extreme temperatures are expected. These areas include: The exhaust manifold The head gasket Surfaces where a different sealant is specified
2. Always follow all the safety recommendations and the directions that are on the pipe sealant container.
3. The surfaces to be sealed must be clean and dry.
4. Use a pipe sealant bead of the size or quantity as specified in the service procedure.

Note. Do not allow the sealant to enter a blind hole. The sealant may prevent the fastener from achieving proper clamp load, cause component damage when the fastener is tightened, or lead to component failure.

1. Apply the pipe sealant bead to the inside of any bolt hole areas.
2. Apply a continuous bead of pipe sealant to 1 sealing surface.
3. Tighten the fasteners in sequence (if specified) and to the proper torque specifications. DO NOT overtighten the fasteners.

Tools & Equipment

1. Special tools are listed and illustrated throughout this section with a complete listing at the end of the section. These tools (or their equivalents) are specially designed to quickly and safely accomplish the operations for which they are intended. The use of these special tools will also minimize possible damage to engine components. Some precision measuring tools are required for inspection of certain critical components. Torque wrenches and a torque angle meter are necessary for the proper tightening of various fasteners.
2. To properly service the engine assembly, the following items should be readily available: Approved eye protection and safety gloves A clean, well-lit, work area A suitable parts cleaning tank A compressed air supply Trays or storage containers to keep parts and fasteners organized An adequate set of hand tools Approved engine repair stand An approved engine lifting device that will adequately support the weight of the components.

Scheme 1464

Scheme 1465

Scheme 1466

Scheme 1467

Scheme 1468

Scheme 1469