Pistons, connecting rods and piston rings (Opel Frontera B)

Removal

Remove the engine from the car (see the relevant chapter).

Install the engine on the KM-4120 stand using KM-412-16 adapters.

Remove the oil pan (see the relevant chapter).

Remove the balance shaft assembly (see the relevant chapter).

Remove the cylinder head (see the relevant chapter).

Apply marks to the connecting rod caps (1), making sure that the projections (2) on the connecting rod caps are located on the flywheel side.



Remove the bolts and the connecting rod caps.

Remove the connecting rod bearing shells from the connecting rods and connecting rod caps.

Check for steps or carbon deposits at the top of each cylinder. Using a special tool, remove the step at the top of the cylinders.

Warning: If the pistons are removed without removing the step at the top of the cylinder, damage to the piston rings and pistons may occur.

Use a wooden block or a hammer handle to push the piston and connecting rod out of the cylinder.

Notes:

• Keep the connecting rod bearing shells, connecting rod and cap together.
• Mark the pistons according to the cylinder numbers they were installed in.

Replacing the piston

Before removing the piston pin (2), mark the installation position of the connecting rod (5) relative to the piston (4), with the protrusion (6) on the connecting rod located on the opposite side in relation to the direction indicated by the arrow (3) on the piston bottom.



Lubricate the piston pin with engine oil. Manually install the piston pin into the piston and connecting rod until the groove is accessible.

Insert the retaining ring (1) into the groove so that the ring cut is at the top in zone (I). The angle I should not exceed 30°.

Removal and installation piston rings

Using special pliers (1), remove the piston rings from the piston.

Use a special tool or a piece of a broken piston ring to clean the piston ring grooves.



Clean the piston with a brush and solvent.

Note: Do not use a wire brush.

Measure the piston ring gap by manually inserting a piston ring into the engine cylinder. Use the bottom of the piston to push the piston ring into the engine cylinder. Use a metal feeler gauge to measure the gap in the piston ring joint. If the clearance exceeds the maximum permissible value, replace the piston ring. If the gap is too large, check the cylinder diameter.



Piston ring gap:

• first compression ring (I): 0.30-0.50 mm
• second compression ring (II): 0.30-0.50 mm
• oil scraper ring (III): 0.40-1.40 mm

Insert a new piston ring into the piston groove and use a feeler gauge to measure the gap between the piston ring and the groove wall. If the clearance exceeds the maximum permissible value, replace the piston.





Clearance between piston ring and piston groove:

• first compression ring: 0.02-0.040 mm
• second compression ring: 0.02-0.040 mm
• oil scraper ring: 0.01-0.03 mm

Using piston ring pliers, install the compression rings onto the piston, with the "TOP" marks on the rings facing upwards.

Measuring clearances in crankshaft connecting rod bearings

Measuring gaps using a calibrated plastic rod Plastigage

To measure the clearance in the crankshaft connecting rod bearings, it is necessary to use a calibrated plastic Plastigage rod.

Apply marks (1) to determine the relative positions of the connecting rod and connecting rod cap.



Remove the bolts and cover and connecting rod bearing shell. Clean the bearing, cover and crankshaft journal.





Cut a piece of Plastigage plastic gauge rod the same length as the bearing width and place it along the crankshaft axis on the connecting rod bearing journal.

Install the connecting rod bearing cap with the liner and secure it with new bolts, tightening them as follows:

• 1st pass: tighten the bolts to 35 Nm;
• 2nd pass: tighten the bolts to an angle of 45°;
• 3rd pass: tighten the bolts by an additional 15°.

Warning! Do not turn the crankshaft.

Loosen the bolts and remove the connecting rod bearing cap again. Compare the width of the deformed Plastigage plastic rod with the measuring scale printed on the plastic rod packaging. Use the scale to determine the gap.



Nominal clearance in the crankshaft connecting rod bearing: 0.010-0.061 mm



If the clearance exceeds the permissible value, replace the crankshaft connecting rod bearing shells as a set.

Install the connecting rod bearing cap with the liner and secure it with new bolts, tightening them to the required torque.

Measuring clearances using a bore gauge and micrometer

Note: To measure connecting rod bearing clearances using a bore gauge and micrometer, the crankshaft must be removed from the engine.

Install the connecting rod bearing shells into the connecting rod and connecting rod cap.

Install the connecting rod cap onto the connecting rod and secure with new bolts, tightening them as follows:

• 1st pass: tighten the bolts to 35 Nm;
• 2nd pass: tighten the bolts to an angle of 45°;
• 3rd pass: tighten the bolts by an additional 15°.

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Note: When checking connecting rod bearing clearances, the connecting rod cap bolts can be used multiple times.

Using a bore gauge, measure the inside diameter of the crankshaft connecting rod bearing.



Calculate the average diameter of the connecting rod bearing bore using the formula:

Average bore diameter of connecting rod bearing = (I + II + III): 3



Example:

• I = 42.738 mm
• II = 42.732 mm
• III = 42.741 mm

Average bore diameter of connecting rod bearing = (42.738 + 42.732 + 42.741): 3 = 42.737mm

Using a micrometer, measure the diameter of the crankshaft connecting rod journal in two diametrically perpendicular planes.



Calculate the average diameter of the crankshaft journal using the formula:

Average diameter of crankshaft journal = (I + II): 2

Example:

• I = 42.729 mm
• II = 42.725 mm

Average diameter of crankshaft journal = (42.729 + 42.725): 2 = 42.727 mm

Calculate the clearance in the crankshaft connecting rod bearing by subtracting the average diameter of the crankshaft connecting rod journal from the average diameter of the connecting rod bearing bore.

Nominal clearance in the crankshaft connecting rod bearing: 0.010-0.061 mm

Installation

Position the compression ring locks at an angle of 120°.





Lubricate the piston and piston rings with engine oil. Install the piston with piston rings over the first cylinder, with the arrow on the piston pointing towards the front of the cylinder block and the mark (1) on the connecting rod facing the flywheel. Using a special tool, compress the piston rings onto the piston.



Use the hammer handle to push the piston into the cylinder. After the piston and connecting rod have come out of the special device, before installing the piston in place, make sure that the connecting rod is correctly aligned with the crankshaft journal.

Warning! When installing pistons, press a special device for compressing piston rings firmly against the cylinder block, which will prevent the piston rings from expanding before they enter the cylinder.

Lubricate the working surfaces of the new connecting rod bearing shells with engine oil and install them into the connecting rods and connecting rod caps.

In accordance with the marking, install the connecting rod caps on the connecting rods, making sure that the protrusions (2) on the connecting rod caps are located on the flywheel side, and secure with new bolts, tightening them as follows:

• 1st pass: tighten the bolts to 35 Nm;
• 2nd pass: tighten the bolts to an angle of 45°;
• 3rd pass: tighten the bolts by an additional 15°.

Install the cylinder head (see the relevant chapter).

Install the balance shaft block (see the relevant chapter).

Install the oil pan (see the relevant chapter).

Install the engine into the car (see the relevant chapter).