Hyundai Elantra (CN7): Cylinder Head Assembly / CVVD Assembly

Hyundai Elantra (CN7) 2021-2026 Service Manual / Engine Mechanical System / Cylinder Head Assembly / CVVD Assembly

Description and operation

Description
CVVD (Continuous Variable Valve Duration) System is a device to control the optimum open and close timing according to the driving mode by changing the valve opening section.
It is composed of cam shaft, CVVD assembly, and CVVD acatuator.
The valve opening time operates in proportion to the rpm of control shaft.

Operation Principle
[CVVD System Operating Mode]
Optimum Valve Timing by Engine Load

Repair procedures

Removal
1.
Disconnect the battery negative terminal.
2.
Remove the cylinder head cover.
(Refer to Cylinder Head Assembly - "Cylinder Head Cover")
3.
Turn the crankshaft damper pulley so that No. 1 piston is at top dead center.
(1)
Turn the crankshaft damper pulley and align its groove with the timing mark on the timing chain cover

(2)
Check the timing chain, be sure that the timing mark (A) of each sprocket is matched with the timing mark (B) (color link) of the timing chain.
If not, turn the crankshaft damper pulley by one revolution (360°).
[Intake CVVT]

[Exhaust CVVT]

4.
Remove the Intake variable force solenoid (VFS) valve (A).

5.
Remove the cam to cam guide (A).

6.
Reomve the front bearing cap (A) and intake camshaft bearing caps (B).

7.
Remove the service hole bolt (A).

8.
Remove the engine mounting support bracket.
(Refer to Engine and Transaxle Assembly - "Engine Mounting")
9.
Lift the engine using the jack to obtain space.
10.
Release the lock by putting down rachet plate (B) of timing chain tensioner with using back of tiny awl (A).

11.
Remove the intake oil control valve (OCV) & center bolt (A).

   
•
To prevent impurities from entering intake oil control valve (OCV) & center bolt, wear rubber gloves.
•
Intake oil control valve (OCV) and center bolt, hold the hexagonal portion on the camshaft with a wrench to prevent the camshaft from rotating.

12.
Remove the CVVD assembly.
   
•
After removing the CVVD unit, make sure that the parts such as lifter, cam, etc are not separated.
•
Ensure that the CVVD components are not damaged.
When Using the CVVD fixture
(1)
Install the CVVD fixture (A) over the CVVD assembly.

(2)
Remove the CVVD assembly.

When not using the CVVD fixture
(1)
Remove the CVVD assembly.

13.
Remove the Intake CVVT (A).

Installation
1.
Install the Intake CVVT (A).

2.
Install the CVVD assembly (A).

   
•
After installing the CVVD, check whether the swing arm is separated or is installed correctly.
•
When installing the intake camshaft, spray the engine oil to the camshaft journal installing part (A) of the cam carrier.
The amount of application should be enough to flow down both the front and back sides when it is applied to the center.
•
For installation, the timing mark (A) of the intake CVVT and the timing chain mark (B) should be matched.

   
•
During the installation, there should be no artifical rotation or movement of the guide bracket and control shaft.
•
When removing the CVVD fixing jig, be sure to securely tighten the M6 bolts.
•
If CVVD fixing jig is available, be sure to work by using it.
When Using the CVVD fixture
1. When installing the CVVD assembly mounting bolts (M6), tighten sequence shown.
Tightening torque :
1ST
4.9 - 6.9 N.m (0.5 - 0.7 kgf.m, 3.6 - 5.1 lb-ft)
2nd
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

2. Remove the CVVD fixture (A).

3. Provisionally tighten the CVVD assembly mounting bolts (M8) in sequence shown below.
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

4. Remove the CVVD assembly mounting bolts (M6) (A).

5. Provisionally tighten the CVVD assembly mounting bolts (M6) in sequence shown below.
Tightening torque :
4.9 - 6.9 N.m (0.5 - 0.7 kgf.m, 3.6 - 5.1 lb-ft)

6. Tighten the CVVD assembly mounting bolts (M8) in sequence shown below.
Tightening torque :
18.6 - 22.6 N.m (1.9 - 2.3 kgf.m, 13.7 - 16.6 lb-ft)

7. Tighten the CVVD assembly mounting bolts (M6) in sequence shown below.
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

8. Measure the clearance between the control shaft bearing cap and the end of control shaft using a clearance gauge.
Clearance : 0.0 - 0.05 mm (0.0 - 0.002 in.)

When not using the CVVD fixture
1. Provisionally tighten the CVVD assembly mounting bolts (M6) in sequence shown below.
Tightening torque :
4.9 - 6.9 N.m (0.5 - 0.7 kgf.m, 3.6 - 5.1 lb-ft)

2. Provisionally tighten the CVVD assembly mounting bolts (M8) in sequence shown below.
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

3. Tighten the CVVD assembly mounting bolts (M8) in sequence shown below.
Tightening torque :
18.6 - 22.6 N.m (1.9 - 2.3 kgf.m, 13.7 - 16.6 lb-ft)

4. Tighten the CVVD assembly mounting bolts (M6) in sequence shown below.
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

5. Release the torque of control shaft bearing cap bolt (A).

6. Push the control shaft bearing cap as close as possible in the direction of the arrow.

7. Install the control shaft bearing cap mounting bolts (A).
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

8. Measure the clearance between the control shaft bearing cap and the end of control shaft using a clearance gauge.
Clearance : 0.0 - 0.05 mm (0.0 - 0.002 in.)

3.
Install the intake OCV & center bolt (A).
Tightening torque :
22.6 - 26.5 N.m (2.3 - 2.7 kgf.m, 16.6 - 19.5 lb-ft) + 32 - 36°

   
•
To prevent impurities from entering intake oil control valve (OCV) & center bolt, wear rubber gloves.
•
Intake oil control valve (OCV) and center bolt, hold the hexagonal portion on the camshaft with a wrench to prevent the camshaft from rotating.

4.
Compress the timing chain tensioner piston.
(1)
With a pry bar (A), compress the timing chain tensioner piston (B).

(2)
With a thin gimlet (A), raise the ratchet plate (B) of the timing chain tensioner and fix the piston.

   
•
Do not remove the pick (A).
5.
Install the front bearing cap and camshaft bearing cap
   
•
If there is enough engine oil on the camshaft front bearing cap and camshaft bearing cap installing bolt and bolt hole, tighten to the minimum required tightening torque.
•
Apply engine oil the upper part of the intake / exhaust camshaft journal, then install the camshaft front bearing cap and camshaft bearing cap. The amount of application should be enough to flow down both the front and back sides when it is applied to the center.
(1)
Install the front bearing cap (A) and intake camshaft bearing cap (B).

6.
Remove the fine gimlets (A) that hold the timing chain tensioner.

7.
When installing the timing chain, be sure that the timing mark (A) of each sprocket is matched with the timing mark (B) (color link) of the timing chain.
[Intake CVVT Timing Mark]

[Exhaust CVVT Timing Mark]

8.
Install the cam to cam guide (A).
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

9.
Install the intake variable force solenoid (VFS) valve (A).
Tightening torque :
9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft)

10.
Install the cylinder head cover.
(Refer to Cylinder Head Assembly - "Cylinder Head Cover")

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