Engine Mechanical - 4.3L: Overhaul GMC Savana H2500

Piston and Connecting Rod Disassemble

Tools Required

J 24086-C Piston Pin Remover/Installer

Scheme 674

Scheme 675

Scheme 676

1. Remove the piston rings from the pistons.
2. Press the piston pin from the connecting rod using the J 24086-C . The piston pin has an interference fit into the connecting rod, and is full floating in the piston.
3. Mark, separate, and organize the parts for assembly.

Piston and Connecting Rod Assemble

Tools Required

J 24086-C Piston Pin Remover/Installer

Important: When assembling the piston and connecting rod, the mark on the top of the piston must point to the front of the engine block. The left bank connecting rods should have the flange face toward the front of the engine block. The right bank connecting rods should have the flange face toward the rear of the engine block.

The new piston pin has an interference fit into the connecting rod and is full floating in the piston.

Scheme 677

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Scheme 679

1. Install the new piston pin and connecting rod assembly. Lubricate the piston pin bores with clean engine oil. Use a torch and apply MILD heat to the piston pin end of the connecting rod. Use the J 24086-C in order to press the new piston pin into the piston and connecting rod assembly. Inspect for the proper installation of the piston and piston pin. The piston must move freely on the new piston pin with no binding or interference. CAUTION: Use a piston ring expander to install the piston rings. The rings may be damaged if expanded more than necessary.
2. Install the piston rings onto the piston. Install the oil control piston ring spacer. Install the lower oil control piston ring. Install the upper oil control piston ring. Install the lower compression piston ring. The mark on the side of the piston ring should face the top of the piston. Install the upper compression piston ring. The mark on the side of the piston ring should face the top of the piston.
3. Space the compression piston ring end gaps 120 degrees apart.
4. Space the oil control piston ring end gaps a minimum of 90 degrees apart.

Cylinder Head Disassemble

Tools Required

J 8062 Valve Spring Compressor

Scheme 680

Scheme 681

1. Use the J 8062 in order to compress the valve springs. Important: Mark, sort, and organize the components so that the components can be reinstalled in their original location and position.
2. Remove the valve stem keys (1).
3. Remove the J 8062 from the cylinder head.
4. Remove the valve spring cap (2).
5. Remove the valve spring (3).
6. Remove the valve stem oil seal (4).
7. Discard the valve stem oil seal.
8. Remove the valve.

Cylinder Head Assemble

Tools Required

1. J 8062 Valve Spring Compressor
2. J 42073 Valve Stem Seal Installer

Important: The exhaust valve oil stem seal has the letters EX (1) molded into the top of the seal. The exhaust valve oil stem seal material is brown in color (2) with a white stripe (3) painted onto the outside diameter of the seal, or the material may be red in color (2) with no paint stripe. The intake valve oil seal is black in color.

Scheme 682

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Scheme 685

1. Assemble the valve into the proper valve guide.
2. Select the proper valve stem oil seal for the specific valve guide.
3. Lubricate the valve stem oil seal and the outside diameter of the valve guide with clean engine oil.
4. Assemble the valve stem oil seal onto the valve stem. WARNING: Wear safety glasses in order to avoid eye damage.
5. Using the J 42073 , install the valve stem oil seal onto the valve guide. Tap the valve stem oil seal onto the valve guide until the J 42073 bottoms against the valve spring seat. Inspect the valve stem oil seal. The valve stem oil seal should not be bottomed against the valve guide. There should be a 1-2 mm (0.03937 - 0.07874 in) gap between the bottom edge of the valve stem oil seal and the valve guide.
6. Install the valve spring (3).
7. Install the valve spring cap (2) onto the valve spring (3), over the valve stem. WARNING: Compressed valve springs have high tension against the valve spring compressor. Valve springs that are not properly compressed by or released from the valve spring compressor can be ejected from the valve spring compressor with intense force. Use care when compressing or releasing the valve spring with the valve spring compressor and when removing or installing the valve stem keys. Failing to use care may cause personal injury.
8. Use the J 8062 to compress the valve spring.
9. Install the valve stem O-ring seal.
10. Install the valve stem keys. Use grease to hold the valve stem keys in place while disconnecting the J 8062 . Tap the end of the valve stem with a plastic-faced hammer to seat the valve stem keys. Inspect the valve stem keys to ensure that they are seated in the upper groove of the valve stem.

Scheme 686

Scheme 687

Scheme 688

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Scheme 691

1. Remove the oil pump driveshaft and oil pump driveshaft retainer. Important: Do not remove the oil pump screen from the pipe. The pipe and oil pump screen are serviced as a complete assembly.
2. Remove the oil pump screen, if necessary. The oil pump screen has a press fit into the oil pump cover.
3. Remove the oil pump cover bolts.
4. Remove the oil pump cover.
5. Remove the oil pump drive gear and the oil pump driven gear.
6. Matchmark the gear teeth for assembly. WARNING: Wear safety glasses in order to avoid eye damage.
7. Remove the following items: The oil pump pressure relief valve spring straight pin The oil pump pressure relief spring The oil pump pressure relief valve

Oil Pump Assemble

Tools Required

J 21882 Oil Suction Pipe Installer

Scheme 692

Scheme 693

Scheme 694

Scheme 695

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Scheme 697

1. Apply clean engine oil GM P/N 12345610 (Canadian P/N 9931930) or equivalent, to the oil pump pressure relief valve, oil pump pressure relief valve spring, and oil pump body. WARNING: Wear safety glasses in order to avoid eye damage. Important: Replace the oil pump pressure relief valve spring when you reuse the oil pump.
2. Install the following items: The oil pump pressure relief valve The oil pump pressure relief valve spring The oil pump pressure relief valve spring straight pin
3. Apply clean engine oil GM P/N 12345610 (Canadian P/N 993193) or equivalent, to the oil pump drive gear, the oil pump driven gear, and the oil pump body internal surfaces.
4. Install the oil pump drive gear and the oil pump driven gear into the oil pump body. Align the matchmarks on the oil pump drive and driven gears. Install the smooth side of the oil pump drive and driven gears toward the oil pump cover.
5. Install the oil pump cover. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
6. Install the oil pump cover bolts. Tighten Tighten the bolts to 12 N.m (106 lb in).
7. Inspect the oil pump for smoothness of operation by turning the oil pump driveshaft by hand.
8. Install the oil pump screen. If removed, replace the oil pump screen. The oil pump screen must have a good press fit into the oil pump body. Mount the oil pump in a soft jawed vise. Apply sealant GM P/N 12346004 (Canadian P/N 10953480) or equivalent, to the end of the oil pump screen pipe. Use the J 21882 and a soft-faced hammer in order to tap the oil pump screen into the pump body. The oil pump screen must align parallel with the bottom of the oil pan when the oil pan is installed. Important: Install a NEW oil pump driveshaft retainer during assembly.
9. Install the oil pump driveshaft and the NEW oil pump driveshaft retainer.

Service Prior to Assembly

1. Dirt will cause premature wear of the rebuilt engine. Clean all the components.
2. Use the proper tools to measure the components when checking for excessive wear. Components not within the manufacturer's specification must be repaired or replaced.
3. When the components are re-installed into an engine, return the components to the original location, position, and direction.
4. During assembly, lubricate all the moving parts with clean engine oil, unless otherwise specified. The engine oil will provide the initial lubrication when the engine is first started.

Piston and Connecting Rod Assemblies

The cast aluminum pistons use two compression rings and one oil control assembly. The piston is a low friction, lightweight design with a flat top and barrel shaped skirt. The piston pins are offset 0.9 mm (0.0354 in) toward the major thrust side (right side) to reduce piston slap as the connecting rod travels from one side of the piston to the other side after a stroke. The piston pins have a floating lit in the piston and are retained by a press fit in the connecting rod. The connecting rods are forged steel. The connecting rods are machined with the rod cap installed for proper clearances and alignments.

Disassembly and Assembly Procedure Revisions

1. Intake manifold disassembly and assembly has changed due to the deletion of the EGR and new Central (MFI) fuel system.
2. Measuring Connecting Rod Bearing Clearances has changed due to a tool revision.
3. Engine Preluber procedure has been added to this section.
4. Discard all used gaskets, seals or O-ring seals unless otherwise indicated.
5. MFI fuel system procedure.

Assembling Components

1. Assemble components using only the sealant (or equivalent) that is specified in the service procedure.
2. Sealing surfaces must be clean and free of debris or oil.
3. Specific components such as crankshaft oil seals or valve stem oil seals may require lubrication during assembly.
4. Components requiring lubrication will be identified in the service procedure.
5. Apply only the amount of sealant specified in the service procedure to a component.
6. Do not allow the sealant to enter into any blind threaded holes, as the sealant may prevent the fastener from clamping properly or cause component damage when tightened. Important: Do not overtighten the fasteners.
7. Tighten the fasteners to the proper specifications.