Kia Niro: Cylinder Head Assembly / Cylinder Head Repair procedures

Kia Niro 2017 (DE HEV) Service Manual / Engine Mechanical System / Cylinder Head Assembly / Cylinder Head Repair procedures

Removal

Engine removal is not required for this procedure.

•	Be sure to read and follow the “General Safety Information and Caution” before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.

•	Be sure to shut off the high voltage circuit according to the “High Voltage Shut-off Procedures” before doing any work related with the high voltage system to avoid serious electrical injuries.

•	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, be careful not to fold the gasket or damage the contacting surface of the gasket.

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

•	Turn the crankshaft pulley so that the No. 1 piston is at TDC (Top dead center).

Mark all wiring and hoses to avoid misconnection.

1.	Shut off the High Voltage circuit. (Refer to Engine Mechanical System - "High Voltage Shutoff Procedure")

2.	Remove the air cleaner assembly. (Refer to Intake and Exhaust System - "Air Cleaner")

3.	Remove the engine room under cover. (Refer to Engine and Transaxle Assembly - "Engine Room Under Cover")

4.	Drain the engine coolant. (Refer to Cooling System - "Coolant")

5.	Drain the inverter coolant. (Refer to Hybrid Motor System - "Coolant")

6.	Disconnect the radiator upper hose (A).

7.	Disconnect the radiator lower hose (A).

8.	Remove the hybrid power control unit (HPCU) and tray. (Refer to Hybrid Control System - "Hybrid Power Control Unit (HPCU)")

9.	Disconnect the reservoir tank coolant hose (A).

10.	Disconnect the hybrid starter generator (HSG) coolant hose (A).

11.	Disconnect the electric water pump (EWP) coolant hose (A).

12.	Remove the high pressure fuel pump foam (A).

13.	Disconnect the fuel hose (A) and purge control solenoid valve (PCSV) hose (B).

14.	Disconnect the heater hose (A).

15.	Remove the front muffler. (Refer to Intake and Exhaust System - "Muffler")

16.	Remove the water temperature control assembly and heater pipe. (Refer to Cooling System - "Water Temperature Control Assembly")

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

18.	Remove the hybrid starter generator (HSG). (Refer to Hybrid Motor System - "Hybrid Starter Generator (HSG)")

19.	Remove the electric EGR control valve. (Refer to Engine Control/Fuel System - "Electric EGR Control Valve")

20.	Remove the spark plugs. (Refer to Engine Electrical System - "Spark Plug")

21.	Remove the cylinder head cover. (Refer to Cylinder Head Assembly - "Cylinder Head Cover")

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

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

24.

Remove the CVVT & camshaft.

(1)	Remove the camshaft front bearing cap and camshaft bearing cap in the sequence shown.

(2)	Remove the exhaust CVVT & camshafts (A) and intake camshaft (B).

25.

Remove the hydraulic lash adjuster (HLA) (A) and the swing arm (B).

The HLA and swing arm should be kept together in pair during storage after removal and reinstallation.

26.

Remove the cylinder head.

(1)

Using triple square wrench, uniformly loosen and remove the 10 cylinder head bolts, in several passes, in the sequence shown. Remove the 8 cylinder head bolts and plate washers.

Removing bolts in an incorrect order may result in head warpage or cracks.

(2)

Lift the cylinder head (A) from the dowels on the cylinder block and place the cylinder head on wooden blocks on a bench.

Be careful not to damage the contacting surfaces of the cylinder head and cylinder block.

(3)	Remove the cylinder head gasket (A).

Disassembly

Identify valves and valve springs as they are removed so that each item can be reinstalled in its original position.

Remove the valves.

(1)

Using the SST (09222-3K000, 09222-3K100), compress the valve spring and remove the retainer lock (A).

When installing the SST, insert the front support directly into the bolt hole on the cylinder head.

(2)	Remove the spring retainer (B).

(3)	Remove the valve spring (C).

(4)	Remove the valve (D).

(5)

Using needle-nose pliers, remove the valve stem seal (E).

Do not reuse the valve stem seals.

Inspection

Cylinder Head

Inspect for flatness.

Using a precision straight edge and feeler gauge, measure the contacting surface of the cylinder block and check the manifolds for warpage.

Flatness of cylinder head gasket surface :

Less than 0.05 mm (0.0020 in.) for total area

Less than 0.02 mm (0.0008 in.) for a section of 100 mm (3.9370 in.) X 100 mm (3.9370 in.)

Flatness of manifold mounting surface :

Less than 0.10 mm (0.0039 in.)

2.	Inspect for cracks. Check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks. If cracked, replace the cylinder head.

Valve And Valve Spring

Inspect valve stems and valve guides.

(1)

Using a caliper gauge, measure the inside diameter of the valve guide.

Valve guide inner diameter :

Intake : 5.500 - 5.512 mm (0.21654 - 0.21701 in.)

Exhaust : 5.500 - 5.512 mm (0.21654 - 0.21701 in.)

(2)

Using a micrometer, measure the diameter of the valve stem.

Valve stem outer diameter :

Intake : 5.465 - 5.480 mm (0.21516 - 0.21575 in.)

Exhaust : 5.458 - 5.470 mm (0.21488 - 0.21535 in.)

(3)

Subtract the valve stem diameter measurement from the valve guide inside diameter measurement.

If the clearance is greater than specification, replace the valve or the cylinder head.

Valve stem-to-guide clearance :

[Standard]

Intake : 0.020 - 0.047 mm (0.00079 - 0.00185 in.)

Exhaust : 0.030 - 0.044 mm (0.00118 - 0.00252 in.)

Inspect the valves.

(1)	Check that the valve is ground to the correct valve face angle.

(2)	Check the surface of the valve for wear. If the valve face is worn, replace the valve.

(3)

Check the valve head margin thickness.

If the margin thickness is less than specification, replace the valve.

Margin

[Standard]

Intake : 1.35 - 1.65 mm (0.0531 - 0.0650 in.)

Exhaust : 1.60 - 1.90 mm (0.0630 - 0.0748 in.)

(4)

Check the valve length.

Valve length :

Intake: 100.94 mm (3.9740 in.)

Exhaust: 101.09 mm (3.9740 in.)

(5)	Check the surface of the valve stem tip for wear. If the valve stem tip is worn, replace the valve.

Inspect the valve seats and the valve guides.

(1)	Check the valve seat for evidence of overheating and improper contact with the valve face. If the valve seat is worn, replace the cylinder head.

(2)	Check the valve guide for wear. If the valve guide is worn, replace the cylinder head.

Inspect the valve springs

(1)	Using a steel square, measure the out-of-square of valve spring.

(2)

Using a vernier calipers, measure the free length of valve spring.

If the free length is not as specified, replace the valve spring.

Valve spring :

[Standard]

Free height:

50.27 mm (1.9791 in.)

Load :

16.4 ± 0.8 kgf·m / 35.5 mm (36.16 ± 1.76 lb·f / 1.3976 in.) 26.0 ± 0.9 kgf·m / 22.7 mm (57.32 ± 1.98 lb·f / 0.8937 in.)

Out-of-square :

Less than 1.5°

HLA (Hydraulic Lash Adjuster)

With the HLA filled with engine oil, hold A and press B by hand.

If B moves, replace the HLA.

Problem

Possible cause

Action

1. Temporary noise when starting a cold engine

Normal

This noise will disappear after the oil in the engine reaches the normal pressure.

2. Continuous noise when starting the engine after being parked for more than 48 hours

Oil leakage of the high pressure chamber on the HLA, allowing air to get in

Noise will disappear within 15 minutes when engine runs at 2000-3000 rpm.
If it doesn’t disappear, refer to step 7 below.

3. Continuous noise when the engine is first started after rebuilding cylinder head

Insufficient oil in cylinder head oil gallery

4. Continuous noise when the engine is started after excessively cranking the engine by the starter motor or band

•	Oil leakage of the high-pressure chamber in the HLA, allowing air to get in

•	Insufficient oil in the HLA

5. Continuous noise when the engine is running after changing the HLA

Do not run engine at a speed higher than 3000 rpm, as this may damage the HLA.

6. Continuous noise during idle after high engine speed

Engine oil level too high or too low

•	Check oil level.

•	Drain or add oil as necessary.

Excessive amount of air in the oil at high engine speed

Check oil supply system.

Deteriorated oil

Check oil quality.
If deteriorated, replace with specified type.

7. Noise continues for more than 15 minutes

Low oil pressure

Check oil pressure and oil supply system of each part of engine.

Faulty HLA

Remove the cylinder head cover and press HLA down by hand.
If it moves, replace the HLA.

Reassembly

•	Thoroughly clean all parts to be assembled.

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

•	Replace oil seals with new ones.

Install the valves.

(1)

Using the SST (09222-2G100), push in a new stem seal.

•	Do not reuse old valve stem seals.

•	Incorrect installation of the seal could result in oil leakage past the valve guides.

(2)

Install the valve, valve spring and spring retainer.

Place the valve springs so that the side coated with enamel faces toward the valve spring retainer and then installs the retainer.

(3)

Using the SST (09222-3K000, 09222-3K100), compress the spring and install the retainer locks.

Before releasing the valve spring compressor, ensure that the retainer locks are correctly in place after pushing down and releasing the compressor handle 2 - 3 times.

•	When installing the SST, insert the front support (A) directly into the bolt hole on the cylinder head.

•	Do not press valve retainer by more than 12 mm (0.47 in.).

Installation

•	Thoroughly clean all parts to be assembled.

•	Always use new cylinder head and manifold gaskets.

•	Always use new cylinder head bolts. Cylinder head bolts are toque-to-yield bolts designed to be permanently elongated beyond the state of elasticity when torqued. Reusing the removed bolts can cause the bolts to break or fail to maintain clamping force.

•	The cylinder head gasket is a metal gasket. Be careful not to bend it.

•	Rotate the crankshaft to set the No.1 piston at TDC (Top dead center) on compression stroke.

Install the cylinder head gasket on the cylinder block.

(1)	Remove hardening sealant, oil, dust, moisture and harmful foreign materials from the cylinder block and the cylinder head.

(2)

Apply liquid gasket on the edge of the cylinder block.

Sealant:

Threebond 1217H or equivalent

(3)	Install the cylinder head gasket (A) with the dowel pins of the cylinder block.

(4)

Apply liquid gasket on the edge of the cylinder head gasket.

Sealant:

Threebond 1217H or equivalent

Assemble the cylinder head gasket and the cylinder head within 5 minutes after applying sealant.

Install the cylinder head assembly.

(1)	Carefully place the cylinder head (A) so as not to damage the gasket.

(2)

Tighten the cylinder head bolts and plate washers, in several passes, in the sequence shown.

Tightening torque :

[12.7 - 16.7 N.m (1.3 - 1.7 kgf.m, 9.4 - 12.3 lb-ft)] + [120 - 125°] + [120 - 125°]

Always use new cylinder head bolts. Cylinder head 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.

Install the hydraulic lash adjuster (HLA) (A) and the swing arm (B).

(1)	When installing HLA, it should be held upright so that engine oil in HLA may not spill and assured that dust does not adhere to HLA.

(2)

HLA should be inserted carefully to the cylinder head not to spill engine oil.

Stroke the lash adjuster in engine oil by pushing its cap 4 to 5 times while pushing the ball down slightly using a hard steel wire. Be careful not to give the ball a hard push because the ball weighs just several grams. If it is installed with engine oil spilt out of the lash adjuster and air in it, abnormal noise may be generated.

4.	Install the remaining parts in the reverse order of removal.

Add all the necessary fluids and check for leaks.

Connect KDS/GDS. Check for codes, note, and clear. Recheck.

•	Refill engine with engine oil.

•	Refill the radiator the reservoir tank with engine coolant.

•	Clean battery posts and cable terminals and assemble.

•	Inspect for fuel leakage.

–	After assembling the fuel line, switch on the ignition (without operating the starter) so that the fuel pump runs for approximately two seconds and fuel line pressurizes.

–	Repeat this operation two to three times, then check for fuel leakage at any point in the fuel line.

•	Bleed air from the cooling system.

–	Start engine and let it run until it warms up (until the radiator fan operates 3 to 4 times).

–	Turn off the engine. Check the level in the radiator, add coolant if needed. This will allow trapped air to be released from the cooling system.

–	Put radiator cap on tightly, then run the engine again and check for leaks.

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