Engine Mechanical - 5.3L: Overhaul GMC Envoy II

Piston and Connecting Rod Disassemble

1. Remove the connecting rod bearings from the rod and cap.
2. Using piston ring pliers, remove the piston rings from the piston.
3. Rotate the piston pin retainers until the ring end gap is positioned in the cutout area (1) of the pin bore.
4. Remove the retainers starting in the cutout area of the pin bore.
5. Remove the pin from the piston and connecting rod.
6. The piston and pin are a matched set and are not to be serviced separately. Mark, sort, or organize the piston and the matching piston pin.

Piston and Connecting Rod Assemble

1. Assemble the piston and connecting rod with the lug (1) on the bottom of the piston and the tab (2) on the side of the connecting rod facing the same direction. When installing the piston and connecting rod assembly, the mark on the top of the piston and the tab (2) on the side of the connecting rod should face the front of the engine.
2. Install the retainer. The retainer should be seated in the groove of the pin bore.
3. Install the piston pin to the piston and connecting rod.
4. Install the retainer. The retainer should be seated in the groove of the pin bore.
5. Identify the compression and oil control rings for proper installation. The upper compression ring can be identified by a paint mark (3) located 180 degrees from the end gap. The lower compression ring can be identified by a paint mark (3) located 90 degrees from the end gap. Both rings should be installed with the orientation marks (1, 2) facing the top of the piston.
6. Using piston ring pliers, install the piston rings onto the piston.
7. Position the oil control ring end gaps a minimum of 25 mm (1.0 in) from each other.
8. Position the compression ring end gaps 180 degrees opposite each other.
9. Install the connecting rod bearings (104) to the rod (105) and cap (103).

Oil Pump Disassemble

1. Remove the oil pump cover bolts (408).
2. Remove the oil pump cover (409).
3. Remove the drive gear (410).
4. Remove the driven gear (412).
5. Remove the pressure relief valve plug (416).
6. Remove the pressure relief valve spring (415).
7. Remove the pressure relief valve (414).
8. Inspect the oil pump components. Refer to «Oil Pump Cleaning and Inspection»(ref-200397-S18552134552005102000000) .

Oil Pump Assemble

1. Install the driven gear (412) into the pump housing (413). Install the driven gear with the orientation mark facing the pump cover.
2. Install the drive gear (410) into the pump housing.
3. Install the oil pump cover (409).
4. Install the pump cover bolts (408). Tighten: Tighten the oil pump cover bolts to 12 N.m (106 lb in).
5. Install the relief valve (414).
6. Install a NEW relief valve spring (415).
7. Install the pressure relief valve plug (416). Tighten: Tighten the pressure relief valve plug to 12 N.m (106 lb in).
8. Inspect the oil pump for smooth operation by rotating the drive gear.

Service Prior to Assembly

1. Dirt or debris will cause premature wear of the rebuilt engine. Clean all components. Refer to «Cleanliness and Care»(ref-200397-S20746064332005102000000) .
2. Use the proper tools to measure components when inspecting for excessive wear. Components that are not within the manufacturers specifications must be repaired or replaced.
3. When the components are installed into an engine, return the components to their original location, position and direction. Refer to «Separating Parts»(ref-200397-S15772230512005102000000) .
4. During assembly, lubricate all moving parts with clean engine oil. This provides initial lubrication when the engine is first started.

Piston and Connecting Rod Assembly

The pistons are cast aluminum. The pistons use 2 compression rings and 1 oil control ring assembly. The piston is a low friction, lightweight design with a flat or recessed top and barrel shaped skirt. The piston pins are chromium steel and are a full-floating design. The connecting rods are powdered metal. The connecting rods are fractured at the connecting rod journal and then machined for the proper clearance. All applications use a piston with a graphite coated skirt. The piston and pin are to be serviced as an assembly.

Valve Rocker Arm Cover Assemblies

The valve rocker arm covers are cast aluminum and use a pre-molded silicon gasket for sealing. Mounted to each rocker cover are the coil and bracket assemblies. Incorporated into the left cover is the positive crankcase ventilation (PCV) system dirty air passage. Incorporated into the right cover are the oil fill tube and the PCV fresh air passage.

Assembling Components

1. When assembling components, use only the sealant specified or equivalent in the service procedure.
2. Sealing surfaces should 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. When applying sealant to a component, apply the amount specified in the service procedure.
6. Tighten bolts to specifications. Do not overtighten.