Kia Forte: Cylinder Block / Piston and Connecting Rod

Kia Forte 2019-2024 (BD) Service Manual / Engine Mechanical System / Cylinder Block / Piston and Connecting Rod

Components and components location

Components

1. Piston ring (#1)
2. Piston ring (#2)
3. Oil ring
4. Piston

5. Snap ring
6. Piston pin
7. Connecting rod upper bearing
8. Connecting rod lower bearing

Repair procedures

Disassembly

•	Use fender covers to avoid damaging painted surfaces.

•	To avoid damaging the cylinder head, wait until the engine coolant temperature drops below normal temperature (20°C [68°F]) before removing it.

•	When handling a metal gasket, take care not to fold the gasket or damage the contact surface of the gasket.

•	To avoid damage, unplug the wiring connectors carefully while holding the connector portion.

•	Mark all wiring and hoses to avoid misconnection.

•	Turn the crankshaft damper pulley so that the piston of No. 1 cylinder is at TDC (top dead center) on compression stroke.

1.	Remove the engine and transmission assembly from the vehicle. (Refer to Engine and Transmission Assembly - "Engine and Transmission Assembly")

2.	Remove the transaxle assembly. Manual Transaxle System: (Refer to Manual Transaxle System - "Manual Transaxle") DCT (Double Clutch Transmission) System : (Refer to DCT (Double Clutch Transmission) System - "DCT (Double Clutch Transmission)")

3.	Remove the flywheel. (Refer to Cylinder Block - "Flywheel")

4.	Remove the rear oil seal. (Refer to Cylinder Block Assembly - "Rear Oil Seal")

5.	Install the engine assembly to engine stand for disassembly.

6.	Remove the intake manifold. (Refer to Intake and Exhaust System - "Intake Manifold")

7.	Remove the exhaust manifold. (Refer to Intake and Exhaust System - "Exhaust Manifold")

8.	Remove the timing chain. (Refer to Timing System - "Timing Chain")

9.	Remove the cylinder head assembly. (Refer to Cylinder Head Assembly - "Cylinder Head")

10.	Remove the oil cooler. (Refer to Lubrication System - "Oil Cooler")

11.	Remove the oil pan and the oil screen. (Refer to Lubrication System - "Oil Pan")

12.	Remove the ladder frame (A).

13.	Check the connecting rod side clearance.

14.	Check the connecting rod bearing cap oil clearance.

15.

Remove the piston and connecting rod assembly.

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

(2)

Remove the connecting rod bearing caps (A).

Mark the connecting rod and bearing caps to be able to reassemble in the original position and direction.

(3)

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

•	Keep the connecting rod and caps with the bearings assembled together.

•	Arrange the piston and connecting rod assemblies in the correct order.

•	Mark the piston and connecting rod assembly to be able to reassemble in the original position.

16.	Check fit between 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 expender, remove the two compression rings.

(2)	Remove the two side rails and coil spring.

Arrange the piston rings in the correct order.

18.

Disassemble 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

Check the side clearance between piston and connecting rod.

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

Side clearance

Standard : 0.1 - 0.25 mm (0.0039 - 0.0098 in)

Maximum : 0.35 mm (0.0138 in)

•	If out - of - tolerance, install a new connecting rod.

•	If still out - of - tolerance after connecting rod replacement, replace the crankshaft.

Check the connecting rod bearing oil clearance.

(1)	Check the match marks on the connecting rod and cap are aligned to ensure correct reassembly.

(2)	Remove the 2 connecting rod cap bolts.

(3)	Remove the connecting rod cap and lower bearing.

(4)	Clean the crankshaft pin journal and bearing.

(5)	Place a plastigage across the crankshaft pin journal.

(6)

Reinstall the lower bearing and cap, and tighten the bolts.

Tightening torque :

17.7 - 21.6 N·m (1.8 - 2.2 kgf·m, 13.0 - 15.9 lb·ft) + 88° - 92°

•	Do not turn the crankshaft.

•	Always use new connecting rod cap bolts. Connecting rod cap bolts are torque - to - yield bolts designed to be permanently elongated beyond the state of elasticity when torqued, so if the bolts are removed and reused, it may cause the bolts to break or fail to maintain clamping force.

(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 measurement from the plastigage is too wide or too narrow, remove the upper and lower bearing and then install a new bearings with the same color mark.

Recheck the oil clearance.

Do not file, shim on scrape the bearings or the caps to adjust clearance.

(10)

If the plastigage shows the clearance is still incorrect, try the next larger or smaller bearing. Recheck the oil clearance.

If the proper clearance cannot be obtained by using the appropriate larger or smaller bearings, replace the crankshaft and start over.

If the marks are indecipherable because of an accumulation of dirt and dust, do not scrub them with a wire brush or scraper. Clean them only with solvent or detergent.

(11)

Select the bearing by using the selection table.

Connecting Rod Bearing Selection Table

Connecting rod bearing		Connecting rod mark
Connecting rod bearing		A, 0	B, 00	C, 000
Crank shaft pin journal mark	1	E (Pink)	D (Light Green)	C (White)
	2	D (Light Green)	C (White)	B (Black)
	3	C (White)	B (Black)	A (Light Blue)

Inspection Of Connecting Rod

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)

Inspection Of Crankshaft Pin Journal

Mark	Crankshaft pin 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)

[Type A]

Top surface stamp

[Type B]

Bottom surface stamp

Inspection Of Connecting Rod Bearing

Class	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)

Check the connecting rods.

(1)	When reinstalling, make sure that cylinder numbers put on the connecting rod and cap at disassembly match. When a new connecting rod is installed, make sure that the notches for holding the bearing in place are on the same side.

(2)	Replace the connecting rod if it is damaged on the thrust faces at either end. Also if step wear or a severely rough surface of the inside diameter of the small end is apparent, the rod must be replaced as well.

(3)

Using a connecting rod aligning tool, check the rod for bend and twist. If the measured value is close to the repair limit, correct the rod by a press. Any connecting rod that has been severely bent or distorted should be replaced.

Allowable bend of connecting rod :

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

Allowable twist of connecting rod :

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

Piston

Clean the piston.

(1)	Using a gasket scraper, remove the carbon from the piston top.

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

(3)

Using solvent and a brush, thoroughly clean the piston.

Do not use a wire brush.

Check the piston - to - cylinder clearance by calculating the difference between the cylinder bore inner 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 position in the thrust and axial direction.

Cylinder bore diameter :

77.00 - 77.03 mm (3.0315 - 3.0327 in)

(2)

Measure the piston outside diameter at 33.9 mm (1.5697 in) from top land of the piston.

Piston outside diameter :

76.97 - 77.00 mm (3.0303 - 3.0315 in)

Select the piston matching with cylinder bore 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.

Inspection Of Cylinder Bore

Mark	Cylinder bore 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 face.

Inspection Of Piston Outer Diameter

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

Inspect the piston ring side clearance.

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

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 maximum, replace the piston.

Inspect the piston ring end gap.

To measure the piston ring end gap, insert a piston ring into the cylinder bore. Position the ring at right angles to the cylinder wall by gently pressing it down with a 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 specifications, replace the piston rings. If the gap is too large, recheck the cylinder bore inner diameter. If the bore is over the specifications, the cylinder block must be rebored.

Piston Pins

Measure the outer diameter of piston pin

Piston pin diameter :

19.997 - 20.000 mm (0.7872 - 0.7874 in)

Measure the piston pin - to - piston clearance.

Piston pin - to - piston clearance :

0.004 - 0.012 mm (0.0001 - 0.0005 in)

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

Piston pin - to - connecting rod interference :

0.005 - 0.014 mm ( 0.0002 - 0.0006 in)

Reassembly

•	Thoroughly clean all parts to assembled.

•	Before installing the parts, apply fresh engine oil to all sliding and rotating surfaces.

•	Replace all gaskets, O - rings and oil seals with new parts.

Assemble the piston and the connecting rod.

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

(2)	Align the piston front mark and the connecting rod front mark.

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

(4)

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

•	Apply a sufficient amount of engine oil to outer surface of the piston, inner surface of piston pin hole and small end bore of the connecting rod before inserting the piston pin.

•	Be careful not to damage and scratch the small end bore, piston pin hole and piston pin when inserting the piston pin.

•	Set the snap ring firmly so that the snap ring can contact with the whole groove of the piston pin hole.

•	Cutting face of snap ring must be located in the range of 45° to upper side.

Assemble the piston rings.

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

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

(3)	Position the piston rings so that the ring ends are as shown.

Assemble the connecting rod bearings.

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

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

Insert the piston and connecting rod assemblies into the cylinder bores.

Before installing the piston, apply a sufficient amount of engine oil to the ring grooves and cylinder bores.

(1)	Press the piston rings with a ring compressor and check that the rings are securely in place. Then insert the piston into the cylinder bore, and tap it in using the wooden handle of a hammer.

(2)	Stop after the ring compressor pops free, and check the connecting rod-to-crank journal alignment before pushing the piston into place.

(3)

Install the rod caps with bearings, and tighten the bolts.

Tightening torque :

17.7 - 21.8 N·m (1.8 - 2.2 kgf·m, 13.0 - 15.9 lb·ft) + 88 - 92°

Always use new connecting rod cap bolts. Connecting rod cap bolts are torque-to-yield bolts designed to be permanently elongated beyond the state of elasticity when torqued, so if the bolts are removed and reused, it may cause the bolts to break or fail to maintain clamping force.

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

Install the ladder frame.

(1)

Apply the liquid gasket on the ladder frame.

Bead width : 2.5 - 3.5 mm (0.0984 - 0.1378 in)

•	Apply the sealant, THREE-BOND 1217H or LOCTITE 5900H on the ladder frame rail portion and install it within five minutes. If sealant is applied to cylinder block bottom position, the sealant position should be the same as that of the ladder frame rail.

•	Apply sealant along the inner line of the bolt holes.

(2)

Install the ladder frame (A).

Tightening torque :

18.6 - 23.5 N·m (1.9 - 2.4 kgf·m, 13.7 - 17.4 lb·ft)

7.	Assemble the other parts in the reverse order of disassembly.

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