Cruze

Piston, Connecting Rod, and Bearing Cleaning and Inspection

Connecting Rod

Warning: Wear safety glasses when using compressed air in order to prevent eye injury.

1. Clean the connecting rods (1) in solvent and dry with compressed air.
2. Inspect the connecting rod for the following:

•	Signs of being twisted, bent, nicked or cracked.

•	Scratches or abrasion on the connecting rod bearing seating surfaces.

Piston

1. Clean the piston with a cleaning solvent. DO NOT wire brush any parts of the piston.
2. Clean the piston ring grooves.
3. Inspect the piston on the following:

•	Cracked ring lands, skirts or pin bosses

•	Ring grooves for nicks

•	Eroded areas on the top of the piston (1)

•	Scuffed or damaged skirts (2)

•	Worn piston pin bores (3)

4. If there is any excessive wear, replace the piston.
5. Measure the clearance between piston pin and piston bore. Use the following procedure:

Piston Pin To Connecting Rod Bore And Piston Bore Clearance

1. Measure clearance between piston pin and connecting rod bore. Use the following procedure:

1.1.	Measure the piston pin outside diameter.

1.2.	Measure the connecting rod bore diameter.

1.3.	Substract the piston ring diameter from the connecting rod diameter.

1.4.	The clearance should be  0.008 mm - 0.020 mm (0.0003 in - 0.0007 in).

2. If there is excessive clearance, replace the piston pin.
3. If there is still excessive clearance, replace the connecting rod.

3.1.	Measure the piston pin outside diameter.

3.2.	Measure the piston bore diameter.

3.3.	Substract the piston pin diameter from the piston bore diameter.

3.4.	The clearance should be  0.004 mm - 0.017 mm (0.0002 in - 0.0006 in).

4. If there is excessive clearance, replace the piston pin.
5. If there is still excessive clearance, replace the piston.

Piston Ring Clearance

1. Install the piston rings to the cylinder as shown (1) and measure the piston ring end gap. Compare the measurements with those provided below:

•	The upper compression ring end gap should be  0.200 mm - 0.300 mm  (0.0078 in - 0.0118 in).

•	The lower compression ring end gap should be  0.200 mm - 0.300 mm (0.0078 in - 0.0188 in).

•	The oil ring end gap should be  0.200 mm - 0.400 mm (0.0078 in - 0.0157 in).

2. If the clearance is greater than the provided specifications, the piston rings must be replaced.



3. Measure the piston ring side clearance as shown (1). Compare the measurements with those provided below:

•	The upper compression ring side clearance should be  0.090 mm - 0.122 mm (0.0035 in - 0.0048 in).

•	The lower compression ring side clearance should be  0.040 mm - 0.090 mm (0.0015 in - 0.0035 in).

•	The oil ring side clearance should be  0.025 mm - 0.065 mm (0.0009 in - 0.0025 in).

4. If the clearance is greater than the provided specifications, replace the piston rings.
5. If the clearance is still to great, replace the pistons.

Connecting Rod Bearing Clearance (With Micrometer Gauge Internal Measuring Device)

1. Install the connecting bearings and the connecting rod bearing caps.
2. Tighten the connecting rod bearing cap bolts in the following sequence:

Caution: Refer to Fastener Caution in the Preface section.

Note: The old bolts can be reused for the measuring procedure.

2.1.	Tighten the connecting rod bearing cap bolts to  25N·m (18 lb ft).

2.2.	Tighten the bolts to an additional  100°.

2.3.	Tighten the bolts to an additional  15°.




3. Measure the connecting rod bearing diameters at 3 points as shown (1). Use a internal measuring device.
4. Calculate the average connecting rod inner diameter.

Formula: 1. result + 2. result + 3. result / 3




5. Measure the connecting rod journal diameter at 2 points between (1) and (3) and between (2) and (4). Use a micrometer gauge.
6. Calculate the average connecting rod journal diameter.

Formula: 1. result + 2. result / 2.

7. Substract the average connecting rod journal diameter from the average connecting rod bearing diameter in order to determine the connecting rod bearing clearance.

The clearance should be  0.025 mm - 0.058 mm (0.0010 in - 0.0023 in).