Kia Forte: Piston and Connecting Rod Inspection

Second generation YD (2014-2018) / Kia Forte TD 2014-2018 Service Manual / Engine Mechanical System / Cylinder Block / Piston and Connecting Rod Inspection

Connecting Rod

Check the connecting rod side clearance.

Using a feeler gauge, measure the end play while moving the connecting rod back and forth.

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

B.	If still out-of-tolerance, replace the crankshaft.

Side clearance

Standard: 0.10~ 0.25 mm (0.0039 ~ 0.0098 in.)

Check the connecting road bearing oil clearance.

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

(2)	Remove 2 connecting rod cap bolts.

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

(4)	Clean the crank pin and bearing.

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

(6)

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

Tightening torque

1st step:

17.7 ~ 21.6 N.m (1.8 ~ 2.2 kgf.m, 13.0 ~ 15.9 lb-ft)

2nd step: 88 ~ 92°

Do not turn the crankshaft.

•	Do not turn the crankshaft.

•	Always use new connecting rod cap bolts. Connecting rod cap bolts are toque-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 width of the plastigage at its widest point.

Oil clearance:

0.028 ~ 0.046 mm (0.00110 ~ 0.00181 in.)

(9)

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

Do not file, shim, of 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 repeat the check procedure.

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.

Connecting Rod Identification Mark

Connecting Rod Specifications

Class	Mark	Inside Diameter
0	A	48.000 ~ 48.006 mm (1.88976 ~ 1.89000 in.)
1	B	48.006 ~ 48.012 mm (1.89000 ~ 1.89023 in.)
2	C	48.012 ~ 48.018 mm (1.89023 ~ 1.89047 in.)

Crankshaft Pin Identification Mark

Conform to read stamping order as shown arrow direction from #1.

Crankshaft Specifications

Class	Mark	Outside Diameter Of Pin
I	1	44.966 ~ 44.972 mm (1.77031 ~ 1.77055 in.)
II	2	44.960 ~ 44.966 mm (1.77008 ~ 1.77031 in.)
III	3	44.954 ~ 44.960 mm (1.76984 ~ 1.77008 in.)

Connecting Rod Bearing Identification Mark

Connecting Rod Bearing Specifications

Class	Mark	Thickness Of Bearing
A	Blue	1.509 ~ 1.512 mm (0.05941 ~ 0.05953 in.)
B	Black	1.506 ~ 1.509 mm (0.05929 ~ 0.05941 in.)
C	None	1.503 ~ 1.506 mm (0.05917 ~ 0.05929 in.)
D	Green	1.500 ~ 1.503 mm (0.05906 ~ 0.05917 in.)
E	Yellow	1.497 ~ 1.500 mm (0.05894 ~ 0.05906 in.)

(11)

Select a connecting rod bearing using selection chart.

Selection Chart For Connecting Rod Bearings

Assembling Classification Of Bearing		Connecting Rod Identification Mark
Assembling Classification Of Bearing		0 (A)	1 (B)	2(C)
Crankshaft Identification Mark	I (1)	E (Yellow)	D (Green)	C (None)
	II (2)	D (Green)	C (None)	B (Black)
	III (3)	C (None)	B (Black)	A (Blue)

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 for 100 mm (3.94 in.)

Allowable twist of connecting rod:

0.10 mm (0.0039 in.) or less for 100 mm (3.94 in.)

When the connecting rods are installed without bearings, there should be no difference on side surface.

Piston

Clean 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:

81.00 ~ 81.03 mm (3.1890 ~ 3.1902 in.)

Measure position points (from the top of the cylinder block):

30 mm (1.1811 in.) / 60 mm (2.3622 in.) / 90 mm (3.5433 in.)

(2)

Measure the piston outside diameter at 35 mm (1.3780 in) from top land of the piston.

Piston outside diameter:

80.97 ~ 81.00 mm (3.1878 ~ 3.1890 in.)

(1)

Check the cylinder bore size code on the cylinder block side surface.

Cylinder Bore Inner Diameter

Size Code	Cylinder Bore Inner Diameter
A	81.00 ~ 81.01 mm (3.1890 ~ 3.1894 in.)
B	81.01 ~ 81.02 mm (3.1894 ~ 3.1898 in.)
C	81.02 ~ 81.03 mm (3.1898 ~ 3.1902 in.)

(2)

Check the piston size mark on the piston top face.

Piston Outer Diameter

Size Code	Piston Outer Diameter
A	80.97 ~ 80.98 mm (3.1878 ~ 3.1882 in.)
B	80.98 ~ 80.99 mm (3.1882 ~ 3.1886 in.)
C	80.99 ~ 81.00 mm (3.1886 ~ 3.1890 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.

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

Piston ring side clearance

[Standard]

No.1 ring:

0.040 ~ 0.080 mm (0.00157 ~ 0.00315 in.)

No.2 ring:

0.040 ~ 0.080 mm (0.00157 ~ 0.00315 in.)

Oil ring:

0.060 ~ 0.135 mm (0.00236 ~ 0.00531 in.)

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

Inspect 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: 0.15 ~ 0.30 mm (0.0059 ~ 0.0118 in.)

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

Oil ring : 0.20 ~ 0.70 mm (0.0079 ~ 0.0276 in.)

If the gap exceeds the service limit, replace the piston rings. If the gap is too large, recheck the cylinder bore inner diameter. If the bore is over the service limit, the cylinder block must be replaced.

Piston Pins

Measure the diameter of the piston pin.

Piston pin diameter:

19.996 ~ 20.000 mm (0.78724 ~ 0.78740 in.)