Engine Mechanical - 4.2L: Overhaul Chevrolet TrailBlazer I

Piston and Connecting Rod Disassemble

Tools Required

J 43654 Piston Pin Retainer Clip Remover/Installer

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1. Remove the piston rings using a piston ring expander. IMPORTANT: Two retainers hold the piston pins in place. Reuse the retainers if they are not damaged during removal.
2. Remove the piston pin retaining clips.
3. Remove the piston pin.

Piston and Connecting Rod Assemble

Tools Required

J 43654 Piston Pin Retaining Clip Remover/Installer

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1. Lubricate the piston pin with clean engine oil.
2. Install one of the piston pin retainers into the retainer groove.
3. Install the connecting rod and piston pin. Push the piston pin in until it bottoms against the installed piston pin retainer.
4. Install the second piston pin retainer. IMPORTANT: The piston ring end gaps must be staggered 90 degrees apart. NOTE: Use a piston ring expander to install the piston rings. The rings may be damaged if expanded more than necessary.
5. Install the following components of the bottom ring assembly (oil control ring). 5.1. The expander 5.2. The lower oil control ring 5.3. The upper oil control ring
6. Install the middle ring - compression ring with the manufacturers mark facing up.
7. Install the top ring.

Cylinder Head Disassemble

Tools Required

1. J 8062 Valve Spring Compressor
2. J 42037 Valve Spring Compressor Adapter
3. J 38820 Valve Stem Seal Remover/Installer

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1. Remove the spark plugs. IMPORTANT: Organize the valve train components when disassembling so they can be reassembled in the same location and matched up with the same components as previously installed.
2. Use J 8062 and J 42037 to compress the valve spring.
3. Remove the valve keys.
4. Remove J 8062 and J 42037.
5. Remove the valve spring retainer and valve spring.
6. Remove the valves.
7. Use J 38820 to remove the valve seals.
8. Inspect the water jacket plug, for leakage. Replace if necessary.
9. Inspect the (inner) oil gallery plug, for leakage. Replace if necessary.
10. Inspect the (end) oil gallery plugs, for leakage. Replace if necessary.

Cylinder Head Assemble

Tools Required

1. J 8062 Valve Spring Compressor
2. J 42037 Valve Spring Compressor Adapter
3. J 38820 Valve Stem Seal Remover/Installer

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1. Apply sealant GM P/N United States 12346004, GM P/N Canada 10953480 or equivalent to the threads. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
2. Install the (end) oil gallery plugs. Tighten Tighten the oil gallery plugs to 38 N.m (28 lb ft).
3. Apply sealant GM P/N United States 12346004, GM P/N Canada 10953480 or equivalent to the plugs.
4. Install the (inner) oil gallery plugs.
5. Apply sealant GM P/N United States 12346004, GM P/N Canada 10953480 or equivalent to the plug.
6. Install the water jacket plug.
7. Use J 38820 to install the valve seals. There is only one size valve seal. IMPORTANT: Lubricate the valve stems with clean engine oil before installing.
8. Install the valves. 0.075 mm (0.003 in) oversized valves are available if the valve guides needed to be reamed. Use the same (original size) valve seal.
9. Install the valve spring and the valve spring retainer.
10. Use J 8062 and J 42037 to compress the valve spring.
11. Install the valve keys.
12. Remove J 8062 and J 42037 . IMPORTANT: Do not try to centralize the electrode on the spark plug. The electrode is offset by design.
13. Install the spark plugs.

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1. Remove and discard the rubber ignition coil seals, and the camshaft cover seal.
2. Clean the camshaft cover with a suitable cleaning solvent.
3. Inspect the camshaft cover for cracks or damage.
4. Inspect the bolt threads for damage.
5. Replace the camshaft cover if necessary.

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1. Clean all parts of sludge, oil, and varnish by soaking in carburetor cleaner or cleaning solvent.
2. Inspect for foreign material and determine the source of the foreign material.
3. Inspect the oil pump housing and engine front cover for the following conditions: Cracks or casting imperfections Scoring Damaged threads
4. Do not attempt to repair the oil pump housing. Replace the oil pump housing if damage is found.
5. Inspect the oil pump gears for damage.
6. Measure the inner oil pump gear tip clearance in several places.
7. Measure the outer oil pump gear tip clearance in several places. IMPORTANT: When deciding oil pump serviceability based on end clearance, consider depth of the wear pattern in the pump cover.
8. Measure the oil pump gear side clearance.
9. Inspect the pressure regulator valve for the following conditions: Scoring Sticking Burrs - Burrs may be removed using a fine oil stone.
10. Inspect the pressure regulator valve spring for loss of tension or bending. Replace the pressure regulator spring if damaged.
11. Inspect the oil pump pipe pickup tube and screen assembly for the following conditions: Looseness - If the oil pump pipe pickup tube is loose or bent, replace the oil pump pipe pickup tube. Broken wire mesh or screen Inspect the O-ring seal at the base of the oil pump pickup tube for damage.

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1. Clean the oil pan in solvent. Remove all sludge and debris from the oil pan. IMPORTANT: Do not use a motorized tool or bristle disc to clean this component.
2. Remove all sealing material from the oil pan rails.
3. Inspect the oil pan sealing surfaces for nicks or damage. Remove any minor nicks with a fine flat file.
4. Inspect the threads in the oil drain plug hole.
5. Replace the oil pan if necessary.

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1. Clean the engine front cover with cleaning solvent. IMPORTANT: Do not use a motorized tool or bristle disc to clean this component.
2. Remove all sealing material.
3. Inspect the engine front cover sealing surfaces for nicks or damage. Use a fine flat file to remove any minor nicks.
4. Inspect the engine front cover threaded holes for damage.
5. Repair or replace the engine front cover as necessary.

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1. Clean the intake manifold gasket mating surface.
2. Inspect the threads on the retaining bolts.
3. Inspect the intake manifold for cracks.
4. Replace the intake manifold if necessary.

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1. Clean the exhaust manifold.
2. Inspect the exhaust manifold for cracks or damage.
3. Inspect the exhaust manifold threads and studs (if necessary).
4. Check the exhaust manifold mating surface for flatness. Use a straight edge and a feeler gauge.
5. Replace the exhaust manifold if necessary.

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1. Remove all sealing material from the sealing surface.
2. Inspect the water pump impeller for damage.
3. Inspect the water pump shaft for looseness.
4. Inspect the threads for damage.
5. Replace the water pump if necessary.

Service Prior to Assembly

Dirt will cause premature wear of the rebuilt engine. Clean all of the components. Use the proper tools in order to measure components when inspecting for excessive wear. Repair or replace the components that are not within the manufacturers specification. When components are reinstalled into an engine, return the components to their original location, position, and direction. During assembly, lubricate all of the moving parts with clean engine oil or engine assembly lubricant (unless otherwise specified). This will provide initial lubrication when the engine is first started.