Cylinder Head Assembly: Overview Kia Rio III

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Description

Continuous Variable Valve Timing (CVVT) system advances or retards the valve timing of the intake and exhaust valve in accordance with the ECM control signal which is calculated by the engine speed and load.

By controlling CVVT, the valve over-lap or under-lap occurs, which makes better fuel economy and reduces exhaust gases (NOx, HC) and improves engine performance through reduction of pumping loss, internal EGR effect, improvement of combustion stability, improvement of volumetric efficiency, and increase of expansion work.

This system consist of

1. the CVVT Oil Control Valve (OCV) which supplies the engine oil to the cam phaser or runs out the engine oil from the cam phaser in accordance with the ECM PWM (Pulse With Modulation) control signal
2. the CVVT Oil Temperature Sensor (OTS) which measures the engine oil temperature
3. and the Cam Phaser which varies the cam phase by using the hydraulic force of the engine oil.

The engine oil getting out of the CVVT oil control valve varies the cam phase in the direction (Intake Advance/Exhaust Retard) or opposite direction (Intake Retard/Exhaust Advance) of the engine rotation by rotating the rotor connected with the camshaft inside the cam phaser.

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Operation Principle

The CVVT has the mechanism rotating the rotor vane with hydraulic force generated by the engine oil supplied to the advance or retard chamber in accordance with the CVVT oil control valve control.

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1. Remove the cylinder head cover. (Refer to «TIMING SYSTEM»(ref-536072) )
2. Remove the timing chain cover. (Refer to «TIMING SYSTEM»(ref-536072) )
3. Remove the timing chain. (Refer to «TIMING SYSTEM»(ref-536072) )
4. Remove the exhaust oil control valve (OCV) adapter (A).
5. Remove the camshaft bearing caps (A) with the order below and then detach the intake camshaft and exhaust camshaft.
6. Remove the intake CVVT assembly (A) and exhaust CVVT (B).

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1. Inspect the cam height. Using a micrometer, measure the cam height. Cam height Intake: 44.15mm (1.7382in) Exhaust: 43.55mm (1.7146in) If the cam lobe height is less than specified, replace the camshaft.
2. Check the crankshaft journal for wear. If the journal is worn excessively, replace the camshaft.
3. 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 and tighten the bolts with specified torque. Tightening torque 1st step M6 bolt: 5.9 N.m (0.6 kgf.m, 4.3 lb-ft) M8 bolt: 9.8 N.m (1.0 kgf.m, 7.2 lb-ft) 2nd step M6 bolts: 11.8 ~ 13.7N.m (1.2 ~ 1.4kgf.m, 8.7 ~ 10.1lb-ft) M8 bolts: 18.6 ~ 22.6N.m (1.9 ~ 2.3kgf.m, 13.7 ~ 16.6lb-ft) NOTE: Do not turn the camshaft. Remove the bearing caps. Measure the plastigage at its widest point. Bearing oil clearance Standard: 0.027 ~ 0.058 mm (0.0011 ~ 0.0023 in) Limit: 0.1 mm (0.0039 in) If the oil clearance is greater than specified, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
4. 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: 0.1 ~ 0.2 mm (0.0039 ~ 0.0079 in) If the end play is greater than specified, replace the camshaft. If the end play is still greater than specification after camshaft replacement, replace the bearing caps and cylinder head as a set. Remove the camshafts.

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1. Inspect the CVVT for smooth rotation. Clamp the camshaft using a vise. Be careful not to damage the cam lobes and journals in the vise Check that the CVVT is locked by turning it clockwise or counterclockwise. It must not rotate. Intake CVVT: Seal one of the two advance holes in the camshaft journal with tape. Exhaust CVVT: Seal one of the two retard holes in the camshaft journal with tape. (Scheme 149): Identifying Intake And Exhaust CVVT Assemblies Intake CVVT: Apply approx. 150 kPa (1.5 kgf/cm, 21 psi) of compressed air into the unsealed advance hole to release the lock. Exhaust CVVT: Apply approx. 150 kPa (1.5 kgf/cm, 21 psi) of compressed air into the unsealed retard hole to release the lock. CAUTION: Cover the oil paths with a piece of cloth when applying compressed air to prevent oil from spraying. Intake CVVT: With compressed air applied, rotate the CVVT into the advance direction (counterclockwise) within its phasing range and check that the CVVT turns smoothly. Exhaust CVVT: With compressed air applied, rotate the CVVT into the retard direction (clockwise) and check that the CVVT turns smoothly. CVVT phasing range Intake: 25°±1° (from the most retarded position to the most advanced position) Exhaust: 20°±1° (from the most advanced position to the most retarded position) (Scheme 150): Identifying CVVT Assembly Advance And Retard Angle Turning Direction Intake CVVT: Rotate the CVVT into the most retarded position (clockwise) and then check that the CVVT is locked. Exhaust CVVT: Rotate the CVVT into the most advanced position (counterclockwise) and then check that the CVVT is locked.

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1. Install the intake CVVT (A) and exhaust CVVT (B). Tightening torque: 63.7 ~ 73.5 N.m (6.5 ~ 7.5 kgf.m, 47.0 ~ 54.2 lb-ft) CAUTION: When installing the CVVT assembly bolt, prevent the camshaft from rotating by using a wrench.
2. Install the camshaft bearing caps (A) with the order below after setting the intake camshaft and exhaust camshaft on the cylinder head. Tightening torque 1st step M6 bolt: 5.9 N.m (0.6 kgf.m, 4.3 lb-ft) M8 bolt: 9.8 N.m (1.0 kgf.m, 7.2 lb-ft) 2nd step M6 bolts: 11.8 ~ 13.7N.m (1.2 ~ 1.4kgf.m, 8.7 ~ 10.1lb-ft) M8 bolts: 18.6 ~ 22.6N.m (1.9 ~ 2.3kgf.m, 13.7 ~ 16.6lb-ft)
3. Install the exhaust oil control valve (OCV) adapter (A). Tightening torque: 9.8 ~ 11.8 N.m (1.0 ~ 1.2 kgf.m, 7.2 ~ 8.7 lb-ft)
4. Install the timing chain. (Refer to «TIMING SYSTEM»(ref-536072) )
5. Install the timing chain cover. (Refer to «TIMING SYSTEM»(ref-536072) )
6. Install the cylinder head cover. (Refer to «TIMING SYSTEM»(ref-536072) )

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See also:
• INTAKE AND EXHAUST SYSTEM