Hyundai Sonata: Cylinder Head. Repair procedures - Cylinder Head Assembly - Engine Mechanical SystemHyundai Sonata: Cylinder Head. Repair procedures


Use fender covers to avoid damaging painted surfaces.
To avoid damaging the cylinder head, wait until the engine coolant temperature drops below normal temperature 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.
In case of removing the high pressure fuel pump, high pressure fuel pipe, delivery pipe, and injector, there may be injury caused by leakage of the high pressure fuel. So don’t do any repair work right after engine stops.
Remove the engine cover.
Disconnect the battery negative terminal (A).
Remove the air duct (B).

Remove the air cleaner assembly.
Disconnect the breather hose (A), the intensifier hose (B) and brake booster vacuum hose (C).
Disconnect the air intake hose (D) and then remove the air cleaner assembly (E).

Remove the RH front wheel.
Remove the under cover and RH side cover.
Loosen the drain plug, and drain the engine coolant. Remove the radiator cap to drain with speed.
(Refer to Cooling system in this group)
Disconnect the radiator upper hose (A) and lower hose (B).

Disconnect the wiring connectors and harness clamps, and remove the wiring protectors from the cylinder head, intake manifold and exhaust manifold.
Disconnect the exhaust OCV (Oil control valve) connector (A).

Disconnect the VIS (Variable intake system) connector (A), the OPS (Oil pressure switch) connector (B), the injector extension connector (C), the knock sensor connector (D), the alternator connector (E) and the A/C compressor switch connector (F).

Disconnect the ignition coil connectors (A), the fuel pump connector (B) and the intake OCV (Oil control valve) connector (C).

Disconnect the ETC (Electronic throttle control) connector (A) and MAPS (Manifold absolute pressure sensor) & IATS (Intake air temperature sensor) connector (B).

Disconnect the ECTS (Engine coolant temperature sensor) connector (A) the exhaust CMPS (Camshaft position sensor) connector (B), the condenser connector (C), the CKPS (Crankshaft position sensor) connector (D) and the oxygen sensor connector (E).

Disconnect the intake CMPS (Camshaft position sensor) connector (A) and the PCSV (Purge control solenoid valve) connector (B).

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

Remove the vacuum & PCSV (Purge control solenoid valve) pipe assembly (A).

Remove the high pressure pipe (A). (Refer to FL group)

Remove the high pressure fuel pump (A) and the roller tappet (B). (Refer to FL group)

Disconnect the heater hoses (A).

Disconnect the throttle body coolant hoses (A).

Disconnect the oil cooler coolant hoses (A).

Remove the water temperature control assembly (A) with the water inlet pipe (B).

Remove the timing chain.
(Refer to Timing system in this group)
Remove the intake and exhaust manifold.
(Refer to Intake and exhaust system in this group)
Remove the high pressure fuel pump bracket (A).

Remove the intake CVVT assembly (A) and exhaust CVVT assembly (B).

When removing the CVVT assembly bolt, prevent the camshaft from rotating by using a wrench at position A.

Remove the camshaft.
Remove the front camshaft bearing cap (A) with the upper bearing (B).

Remove the camshaft bearing cap (A) in the sequence shown.

Remove the camshafts (A).

Remove the exhaust camshaft lower bearing (A).

Remove the intake OCV (Oil control valve) (A) using a torx wrench.

Remove the exhaust OCV (Oil control valve) (A) using a torx wrench.

Remove the intake CMPS (Camshaft position sensor) (A).

Remove the exhaust CMPS (Camshaft position sensor) (A) after removing the engine hanger (B).

Remove the injector & rail module (A).
(Refer to FL group)

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

Head warpage or cracking could result from removing bolts in an incorrect order.
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 contact surfaces of the cylinder head and cylinder block.
Remove the cylinder head gasket (B).


Identify MLA(Mechanical Lash Adjuster), valves, valve springs as they are removed so that each item can be reinstalled in its original position.
Remove the MLAs (A).

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

Remove the spring retainer.
Remove the valve spring.
Remove the valve.
Using needle-nose pliers, remove the valve stem seal.
Do not reuse old valve stem seals.


Cylinder Head
Inspect for flatness.
Using a precision straight edge and feeler gauge, measure the surface the contacting the cylinder block and the manifolds for warpage.

Flatness of cylinder head gasket surface
Standard : Less than 0.05mm (0.0019in.) for total area
Less than 0.02mm (0.0007in.) for a section of 100mm (3.9370in.) X 100mm (3.9370in.)
Flatness of manifold mounting surface (Intake/Exhaust)
Standard : Less than 0.10mm (0.0039in.)

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

Valve guide inner diameter
Intake / Exhaust : 5.500 ~ 5.512mm (0.21654 ~ 0.21701in.)

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

Valve stem outer diameter
Intake : 5.465 ~ 5.480mm (0.21516 ~ 0.21575in.)
Exhaust : 5.458 ~ 5.470mm (0.214988 ~ 0.21535in.)

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

Valve stem-to-guide clearance
Intake : 0.020 ~ 0.047mm (0.00078 ~ 0.00185in.)
Exhaust : 0.030 ~ 0.054mm (0.00118 ~ 0.00212in.)
Intake : 0.070mm (0.00275in.)
Exhaust : 0.090mm (0.00354in.)

If the clearance is greater than maximum, replace the valve or cylinder head.
Inspect the valves.
Check the valve is ground to the correct valve face angle.
Check that the surface of the valve for wear.
If the valve face is worn, replace the valve.
Check the valve head margin thickness.

Valve head thickness (Margin)
Intake : 1.02mm(0.0401in.)
Exhaust : 1.09mm(0.0429in.)

If the margin thickness is less than minimum, replace the valve.
Check the valve length.

Valve length
Intake : 113.18mm(4.4559in.)
Exhaust : 105.84mm(4.1669in.)
Intake : 112.93mm(4.4461in.)
Exhaust : 105.59m(4.1571in.)

Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, replace the valve.
Inspect the valve seats
Check the valve seat for evidence of overheating and improper contact with the valve face. Replace the cylinder head if necessary.
Check the valve guide for wear. If the valve guide is worn, replace the cylinder head.
Inspect the valve springs.
Using a steel square, measure the out-of-square of the valve spring.
Using a vernier calipers, measure the free length of the valve spring.

Valve spring
Free height : 47.44mm (1.8677in.)
Out-of-square : Less than 1.5°

If the free length is not as specified, replace the valve spring.
MLA (Mechanical Lash Adjuster)
Inspect the MLA.
Using a micrometer, measure the MLA outside diameter.

MLA outer diameter :
31.964 ~ 31.980mm (1.2584 ~ 1.2590in.)

Using a caliper gauge, measure MLA tappet bore inner diameter of cylinder head.

Tappet bore inner diameter :
32.000 ~ 32.025mm (1.2598 ~ 1.2608in.)

Subtract MLA outside diameter measurement from tappet bore inside diameter measurement.

MLA to tappet bore clearance
[Standard] : 0.020 ~ 0.061mm (0.00078 ~ 0.00240in.)
[Limit] : 0.070mm (0.00275in.)

Inspect the cam lobes.
Using a micrometer, measure the cam lobe height.

Cam height
[Standard value]
Intake : 44.10 ~ 44.30mm (1.7362 ~ 1.7440in.)
Exhaust : 44.90 ~ 45.10mm (1.7677 ~ 1.7756in.)

If the cam lobe height is less than standard, replace the camshaft.
Inspect the camshaft journal clearance.
Clean the bearing caps and camshaft journals.
Place the camshafts on the cylinder head.
Lay a strip of plastigage across each of the camshaft journal.

Install the bearing caps.
Do not turn the camshaft.
Remove the bearing caps.
Measure the plastigage at its widest point.

Bearing oil clearance
[Standard value]
Intake :
No.1 : 0.022 ~ 0.057mm (0.00087 ~ 0.00224in.)
No.2, 3, 4, 5 : 0.045 ~ 0.082mm (0.00177 ~ 0.00323in.)
No.1 : 0 ~ 0.032mm (0 ~ 0.00126in.)
No.2, 3, 4, 5 : 0.045 ~ 0.082mm (0.00177 ~ 0.00323in.)
No.1 : 0.090mm (0.00354in.)
No.2, 3, 4, 5 : 0.120mm (0.00472in.)
Exhaust :
No.1 : 0.090mm (0.00354in.)
No.2, 3, 4, 5 : 0.120mm (0.00472in.)

If the oil clearance is greater than maximum, replace the camshaft. If necessary, replace cylinder head.
Completely remove the plastigage.
Remove the camshafts.
Inspect the camshaft end play.
Install the camshafts.
Using a dial indicator, measure the end play while moving the camshaft back and forth.

Camshaft end play
[Standard value] : 0.04 ~ 0.16mm (0.0016 ~ 0.0063in.)
[Limit] : 0.20mm (0.0078in.)

If the end play is greater than maximum, replace the camshaft. If necessary, replace cylinder head.
Remove the camshafts.
Exhaust Camshaft Bearing
Check the cylinder head bore mark.
Cylinder Head Bore Identification Mark

Cylinder Head Specifications
Exhaust No.1 Inside Diameter Of Cylinder Head Bore
40.000 ~ 40.008mm
(1.57480 ~ 1.5751in.)
40.008 ~ 40.016mm
(1.57511 ~ 1.57543in.)
40.016 ~ 40.021mm
(1.57543 ~ 1.57563in.)

Select class of camshaft bearing same as class of cylinder head as shown on the table below.
Exhaust Camshaft Bearing Identification Mark

Exhaust Camshaft Bearing Specifications
Head Bore
Bearing Class For Installing (Color)
Thickness Of Bearing
a (A)
C (Green)
b (B)
B (None color)
c (C)
A (Black)

Oil clearance : 0 ~ 0.032mm (0 ~ 0.00126in.)

CVVT Assembly
Inspect CVVT assembly.
Check that the CVVT assembly will not turn.
Apply vinyl tape to the retard hole except the one indicated by the arrow in the illustration.
Verify the hold to tape and the hole to put air in.


Wind tape around the tip of the air gun and apply air of approx. 150kPa(1.5kgf/cm², 21psi) to the port of the camshaft.
(Perform this in order to release the lock pin.)
When the oil splashes, wipe it off with a shop rag and the likes.
Cylinder Head. Components and Components Location
Components 1. Camshaft bearing cap 2. Camshaft front bearing cap 3. Exhaust camshaft 4. Intake camshaft 5. Exhaust CVVT assembly 6. Intake CVVT assembly 7 ...

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