Kia Optima: Cylinder Head Assembly / CVVT & Camshaft

Kia Optima DL3 2019-2024 Service and Repair Manual / Engine Mechanical System / Cylinder Head Assembly / CVVT & Camshaft

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

Description and operation

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

–	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,

–	the CVVT Oil Temperature Sensor (OTS) which measures the engine oil temperature,

–	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.

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.

[CVVT System Mode]

(1) Low Speed / Low Load	(2) Part Load

(3) Low Speed / High Load	(4) High Speed / High Load

Driving Condition	Exhaust Valve		Intake Valve
Driving Condition	Valve Timing	Effect	Valve Timing	Effect
(1) Low Speed /Low Load	Completely Advance	* Valve Under-lap * Improvement of combustion stability	Completely Retard	* Valve Under-lap * Improvement of combustion stability
(2) Part Load	Retard	* Increase of expansion work * Reduction of pumping loss * Reduction of HC	Retard	* Reduction of pumping loss
(3) Low Speed /High Load	Retard	* Increase of expansion work	Advance	* Prevention of intake back flow (Improvement of volumetric efficiency)
(4) High Speed /High Load	Advance	* Reduction of pumping loss	Retard	* Improvement of volumetric efficiency

Repair procedures

Removal

•	Use fender covers to avoid damaging painted surfaces.

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

•	Mark all wiring and hoses to avoid misconnection.

•	Turn the crankshaft pulley so that the No. 1 piston is at top dead center.

Timing chain cover removal is not required for this procedure.

1.	Remove the cylinder head cover. (Refer to Cylinder Head Assembly - “Cylinder Head Cover”)

Set No.1 cylinder to TDC (Top dead center) on compression stroke.

(1)	Turn the crankshaft pulley and align its groove with the timing mark of the timing chain cover.

(2)	Check that the TDC marks of the intake and exhaust CVVT sprockets are in straight line on the cylinder head surface as shown in the illustration. If not, turn the crankshaft by one revolution (360°) more.

(3)	Mark the timing chains corresponding to the timing marks of the CVVT sprockets.

3.	Remove the crankshaft damper pulley. (Refer to Drive Belt System - “Crankshaft Damper Pulley”)

4.	Remove the service plug bolt (A) with the gasket (B).

5.	Remove the tensioner arm bolt (A).

6.	Push down the tensioner arm (A). [Timing Cover off For illustration Only]

7.	Remove the camshaft bearing caps.

8.	Remove the exhaust camshaft (A) first, then intake camshaft (B).

Remove the tensioner arm (A).

To hold the timing chain, tie it with strap.

10.

Remove the CVVT assembly (A) from the camshaft.

When removing the CVVT assembly bolt, hold the camshaft with a wrench to prevent the camshaft from rotating.

Inspection

Camshaft

Inspect the cam lobes.

Using a micrometer, measure the cam lobe height.

If the cam lobe height is less than specification, replace the camshaft.

Cam height

Intake : 39.0 mm (1.5354 in.)

Exhaust : 38.66 mm (1.5220 in.)

2.	Check the surface of the camshaft journal for wear. If the journal is worn excessively, replace the camshaft.

Inspect the camshaft journal clearance.

(1)	Clean the bearing caps and camshaft journals.

(2)	Place the camshafts on the cylinder head.

(3)	Lay a strip of plastigage across each of the camshaft journal.

(4)

Install the bearing caps and tighten the bolts with specified torque.

Tightening torque

M6 bolts :

11.8 - 13.7 N•m (1.2 - 1.4 kgf•m, 8.7 - 10.1 lb•ft)

M8 bolts :

18.6-22.6 N•m (1.9-2.3 kgf•m, 13.7-16.6 lb•ft)

Do not turn the camshaft.

(5)	Remove the bearing caps.

(6)

Measure the plastigage at its widest point.

If the oil clearance is greater than specification, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.

Bearing oil clearance

Standard :

0.032 - 0.062 mm (0.00126 - 0.00244 in.)

Inspect the camshaft end play.

(1)	Install the camshaft bearing caps.

(2)

Using a dial indicator, measure the end play while moving the camshaft back and forth.

If the end play is greater than specification, replace the camshaft.

If necessary, replace the bearing caps and cylinder head as a set

Camshaft end play

Standard :

0.10 - 0.19 mm (0.0039 - 0.0075 in.)

(3)	Remove the camshafts.

Continuously variable valve timing (CVVT) Assembly

Inspect the CVVT for smooth rotation.

(1)	Clamp the camshaft using a vise. Be careful not to damage the cam lobes and journals in the vise.

(2)	Check that the CVVT is locked by turning it clockwise or counterclockwise. It must not rotate.

(3)	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.

(4)

Intake CVVT : Apply approx. 150 kPa (1.5 kgf/cm², 21 psi ) of compressed air into the unsealed advance hole to release the lock.

Exhaust CVVT : Apply approx. 150 kPa (1.5 kgf/cm², 21 psi ) of compressed air into the unsealed retard hole to release the lock.

Cover the oil paths with a piece of cloth when applying compressed air to prevent oil from spraying.

(5)

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)

(6)	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.

Installation

Install the CVVT assembly (A) to the camshaft.

Tightening torque :

64.7 - 76.5 N•m (6.6 - 7.8 kgf•m, 47.7 - 56.4 lb•ft)

When installing the CVVT assembly bolt, hold the camshaft with a wrench to prevent the camshaft from rotating.

Compress the piston of the tensioner using a handy bar (A) and then insert a stopper pin (B) into the hole on the tensioner to hold the compressed piston.

The tensioner should be retracted completely by pushing the SST 09240 - 2E100 deep.

If the SST 09240 - 2E100 is insert incompletely as shown in image below, it may cause the tensioner function problem.

3.	Place the intake camshaft (A) and then insert the tensioner arm (B) along the timing chain.

Place the exhaust camshaft (A).

The timing marks of each CVVT sprocket should be matched with timing marks (painted link) of timing chain when installing the timing chain.

Install the camshaft bearing caps.

Tighten the bolts, in several passes, in the sequence as shown.

Tightening torque

M6 bolts :

11.8 - 13.7 N•m (1.2 - 1.4 kgf•m, 8.7 - 10.1 lb•ft)

M8 bolts :

18.6 - 22.6 N•m (1.9 - 2.3 kgf•m, 13.7 - 16.6 lb•ft)

Be careful not to change the position and direction of bearing caps.

6.	Using a suitable tool, move the tensioner arm to align the tensioner bolt hole with the service hole.

Install the tensioner arm bolt (A).

Tightening torque :

18.6 - 22.6 N•m (1.9 - 2.3 kgf•m, 13.7 - 16.6 lb•ft)

8.	Remove the stopper pin from the tensioner.

9.	Turn the crankshaft two turns in the operating direction (clockwise), and then check that the TDC marks of the CVVT sprockets are in straight line on the cylinder head surface.

10.

Install a service plug bolt (A) with a gasket.

Tightening torque :

29.4 - 39.2 N•m (3.0 - 4.0 kgf•m, 21.7 - 28.9 lb•ft)

Do not reuse the service plug bolt and gasket.

11.	Install the other parts reverse order of removal.

Cylinder Head Cover

Components and components location Components 1. Cylinder head cover 2. Cylinder head cover gasket Repair procedures Removal ...

Cylinder Head

Components and components location Components 1. Camshaft bearing cap 2. Camshaft front bearing cap 3. Exhaust camshaft 4. Intake camshaft 5. Exhaust CVV ...

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