Kia Forte BD Quiz
Engine Mechanical System

Piston and Connecting Rod

In this manual: Engine Mechanical System
General Information — 8Maintenance — 32Engine Mechanical System — 47Engine Electrical System — 17Emission Control System — 10Engine Control System/Fuel System — 32Clutch System — 11Manual Transmission — 11DCT (Dual Clutch Transmission) System — 16Drive Shaft and Axle — 8Suspension System — 26Steering — 9Restraints — 11Brake System — 27Body (Interior and Exterior) — 119Body Electrical System — 98Heating, Ventilation, and Air Conditioning — 27
36steps
~216min
4/5difficulty
0102030405021.616N·mlb·ft
Tightening torque found on this page
Done 0 of 36

Components and Component Location

Components

1. No. 1 Piston Ring
2. No. 2 Piston Ring
3. Oil Ring
4. Piston		 5. Snap Ring
6. Piston Pin
7. Connecting Rod Upper Bearing
8. Connecting Rod Lower Bearing

Repair Procedures

Disassembly

  1. Remove the engine and transaxle assembly from the vehicle.

    (See Engine and Transaxle Assembly - Engine and Transaxle Installation)

  2. Remove the transaxle assembly.

    Manual Transaxle System:

    (See Manual Transaxle System - Manual Transaxle)

    DCT (Dual Clutch Transmission) System:

    (See DCT (Dual Clutch Transmission) System - DCT (Dual Clutch Transmission))

  3. Remove the flywheel.

    (See Cylinder Block - Flywheel)

  4. Remove the rear oil seal.

    (See Cylinder Block Assembly - Rear Oil Seal)

  5. Install the engine assembly on an engine stand for disassembly.

  6. Remove the intake manifold.

    (See Intake and Exhaust System - Intake Manifold)

  7. Remove the exhaust manifold.

    (See Intake and Exhaust System - Exhaust Manifold)

  8. Remove the timing chain.

    (See Timing System - Timing Chain)

  9. Remove the cylinder head assembly.

    (See Cylinder Head Assembly - Cylinder Head)

  10. Remove the oil cooler.

    (See Lubrication System - Oil Cooler)

  11. Remove the oil pan and oil screen.

    (See Lubrication System - Oil Pan)

  12. Remove the ladder frame (A).

  13. Check the connecting rod side clearance.

  14. Check the oil clearance of the connecting rod bearing cap.

  15. Remove the piston and connecting rod assembly.

    1. Using a ridge reamer, remove all carbon from the top of the cylinder.

    2. Remove the connecting rod bearing caps (A).

    3. Push the piston and connecting rod assembly with the upper bearing through the top of the cylinder block.

  16. Check the fit between the piston and piston pin.

    Try to move the piston back and forth on the piston pin. If any movement is felt, replace the piston and pin as a set.

  17. Disassemble the piston rings.

    1. Using a piston ring expander, remove the two compression rings.

    2. Remove the two side guides and the coil spring.

  18. Remove the connecting rod from the piston.

    1. Remove the snap ring (A) from the piston.

    2. Remove the piston pin (B) from the piston.

    3. Disassemble the piston (C) and connecting rod (D).

Inspection

Connecting Rod

  1. Check the side clearance between the piston and the connecting rod.

    Using a feeler gauge, measure the side clearance while moving the connecting rod back and forth.

    Backlash

    Standard: 0.1–0.25 mm (0.0039–0.0098 in.)

    Maximum: 0.35 mm (0.0138 in.)

    • If out of specification, install a new connecting rod.

    • If the clearance still exceeds the limit after replacing the connecting rod, replace the crankshaft.

  2. Check the connecting rod bearing oil clearance.

    1. Make sure the alignment marks on the connecting rod and cap are aligned to ensure correct assembly.

    2. Remove the 2 connecting rod cap bolts.

    3. Remove the connecting rod cap and lower bearing.

    4. Clean the crankshaft journal and bearing.

    5. Place a piece of Plastigage on the crankshaft journal.

    6. Install the lower bearing and cap onto the connecting rod, then tighten the bolts.

      Tightening torque: 17.7–22 N·m + 88° – 92°

    7. Remove the connecting rod cap and lower bearing.

    8. Measure the Plastigage at its widest point.

      Bearing oil clearance: 0.030–0.050 mm (0.0012–0.0020 in.)

    9. If the Plastigage measurement is too wide or too narrow, remove the upper and lower bearings, then install new bearings with the same color code.

      Recheck the oil clearance.

    10. If the Plastigage indicates that the clearance is still incorrect, try the next larger or smaller bearing. Recheck the oil clearance.

    11. Select the bearing using the selection table.

      Connecting Rod Bearing Selection Table

      Connecting Rod Bearing Connecting Rod Mark
      A, 0 B, 00 C, 000
      Crankshaft Journal Mark 1 E (Pink) D (Light Green) C (White)
      2 D (Light Green) C (White) B (Black)
      3 C (White) B (Black) A (Blue)

      Connecting Rod Inspection

      Mark Connecting rod big end inner diameter
      A, 0 45.000 - 45.006 mm
      (1.7717–1.7719 in.)
      B, 00 45.006 - 45.012 mm
      (1.7719–1.7721 in.)
      C, 000 45.012 - 45.018 mm
      (1.7721–1.7724 in.)

      Crankshaft Journal Inspection

      Mark Crankshaft journal outer diameter
      1 41.966 - 41.972 mm
      (1.6522–1.6524 in.)
      2 41.960 – 41.966 mm
      (1.6520–1.6522 in.)
      3 41.954 - 41.960 mm
      (1.6517–1.6520 in.)

      [Enter]

      Mark on upper surface

      [Type B]

      Mark on lower surface

      Connecting Rod Bearing Inspection

      Grade Color Connecting Rod Bearing Thickness
      A Light
      Blue      		 1.514 - 1.517 mm
      (0.0596–0.0597 in.)
      B Black 1.511 - 1.514 mm
      (0.0595–0.0596 in.)
      C White 1.508 - 1.511 mm
      (0.0594–0.0595 in.)
      D Light
      Green      		 1.505 - 1.508 mm
      (0.0593–0.0594 in.)
      E Pink 1.502 - 1.505 mm
      (0.0591–0.0593 in.)

  3. Inspect the connecting rods.

    1. When reinstalling, make sure the cylinder numbers stamped on the connecting rod and cap match those marked during disassembly. When installing a new connecting rod, make sure the notches that hold the bearing in place are on the same side.

    2. Replace the connecting rod if it is damaged on the thrust surfaces at either end. Also, if the small end inner diameter shows stepped wear or a heavily roughened surface, the connecting rod must also be replaced.

    3. Using a connecting rod aligner, check the connecting rod for bend and twist. If the measured value is close to the repair limit, straighten the connecting rod using a press. Any connecting rod that is severely bent or distorted must be replaced.

      Allowable connecting rod bend:

      0.05 mm (0.0020 in.) or less / 100 mm (3.94 in.)

      Allowable connecting rod twist:

      0.1 mm (0.0039 in.) or less / 100 mm (3.94 in.)

Piston

  1. Clean the piston.

    1. Using a gasket scraper, remove carbon deposits from the top of the piston.

    2. Using a ring groove cleaning tool or a broken piston ring, clean the piston ring grooves.

    3. Using solvent and a brush, thoroughly clean the piston.

  2. Check the piston-to-cylinder clearance by calculating the difference between the cylinder bore diameter and the piston outer diameter.

    Piston-to-cylinder clearance: 0.02–0.04 mm (0.0008–0.0016 in.)

    1. Using a cylinder bore gauge, measure the cylinder bore diameter at positions in the thrust and axial directions.

      Cylinder bore diameter: 77.00–77.03 mm (3.0315–3.0327 in.)

    2. Measure the outer diameter of the piston at 33.9 mm (1.5697 in.) from the piston top surface.

      Piston outer diameter: 76.97–77.00 mm (3.0303–3.0315 in.)

  3. Select a piston that matches the cylinder bore size class.

    Piston-to-cylinder clearance: 0.02–0.04 mm (0.0008–0.0016 in.)

    1. Check the cylinder bore size mark on the side of the cylinder block.

      Cylinder Bore Inspection

      Mark Cylinder Inner Diameter
      A 77.00 – 77.01 mm
      (3.0315–3.0319 in.)
      B 77.01 - 77.02 mm
      (3.0319–3.0323 in.)
      C 77.02 - 77.03 mm
      (3.0323–3.0327 in.)

    2. Check the piston size mark on the piston top surface.

      Piston Outside Diameter Inspection

      Mark Piston Outer Diameter
      A 76.97 - 76.98 mm
      (3.0303–3.0307 in.)
      B 76.98 - 76.99 mm
      (3.0307–3.0311 in.)
      C 76.99 - 77.00 mm
      (3.0311–3.0315 in.)

Piston Rings

  1. Inspect the piston ring side clearance.

    Using a feeler gauge, measure the clearance between a new piston ring and the ring groove wall.

    Piston Ring Side Clearance

    [Standard]

    No. 1 ring: 0.04–0.08 mm (0.0015–0.0031 in.)

    No. 2 ring: 0.04–0.08 mm (0.0015–0.0031 in.)

    Oil ring: 0.02–0.06 mm (0.0008–0.0024 in.)

    [Limit]

    No. 1 ring: 0.1 mm (0.0039 in.)

    No. 2 ring: 0.1 mm (0.0039 in.)

    Oil ring: 0.2 mm (0.0079 in.)

    If the clearance is greater than the maximum, replace the piston.

  2. Inspect the piston ring end gap.

    To measure the piston ring end gap, insert the piston ring into the cylinder bore. Position the ring at a right angle to the cylinder wall by lightly pushing it with the piston. Measure the gap with a feeler gauge.

    Piston Ring End Gap

    [Standard]

    No. 1 ring: 0.14–0.24 mm (0.0055–0.0094 in.)

    No. 2 ring: 0.30–0.45 mm (0.0118–0.0177 in.)

    Oil ring: 0.20–0.40 mm (0.0079–0.0157 in.)

    [Limit]

    No. 1 ring: 0.3 mm (0.0118 in.)

    No. 2 ring: 0.5 mm (0.0197 in.)

    Oil ring: 0.8 mm (0.0315 in.)

    If the gap exceeds the specification, replace the piston rings. If the gap is still too large, re-check the cylinder bore inside diameter. If the bore exceeds the specification, the cylinder block must be bored.

Piston Pin

  1. Measure the piston pin outer diameter.

    Piston pin diameter: 19.997–20.000 mm (0.7872–0.7874 in.)

  2. Measure the piston pin-to-piston clearance.

    Piston pin-to-piston clearance: 0.004–0.012 mm (0.0001–0.0005 in.)

  3. Check the difference between the piston pin outer diameter and the connecting rod small end inner diameter.

    Piston pin-to-connecting rod fit:

    0.005–0.014 mm (0.0002–0.0006 in.)

Installation

  1. Assemble the piston and connecting rod.

    1. Install the snap ring (A) on one side of the piston pin hole.

    2. Align the piston front mark with the connecting rod front mark.

    3. Insert the piston pin (A) into the piston pin hole and the small end bore of the connecting rod.

    4. Install the snap ring (B) on the other side after inserting the piston pin.

  2. Assemble the piston rings.

    1. Install the side rail and the coil spring by hand.

    2. Using a piston ring expander, install the 2 compression rings with the code mark facing up.

    3. Position the piston rings so that the ring end gaps are as shown in the illustration.

  3. Assemble the connecting rod bearings.

    1. Align the bearing tang (A) with the groove of the connecting rod and cap (B).

    2. Install the bearings (A) into the connecting rod and cap (B).

  4. Insert the piston and connecting rod assembly into the cylinder bores.

    1. Compress the piston rings using a piston ring compressor and make sure the rings are securely retained. Then insert the piston into the cylinder bore and tap it lightly with the wooden handle of a hammer.

    2. Stop after the piston ring compressor is released and check the alignment of the connecting rod with the crankpin before installing the piston in place.

    3. Install the connecting rod caps with bearings and tighten the bolts.

      Tightening torque: 17.7–22 N·m + 88 – 92°

  5. Check the side clearance between the piston and the connecting rod.

  6. Install the oil pan frame.

    1. Apply liquid sealant to the ladder frame.

      Bead width: 2.5–3.5 mm (0.0984–0.1378 in.)

    2. Install the oil pan frame (A).

      Tightening torque: 18.6 – 24 N·m

  7. Assemble the remaining components in the reverse order of removal.

Test yourself

A quick Kia Forte BD quiz: every answer comes with an explanation and a link to the manual page.