Cylinder head — check (Nissan Serena C24)

Cylinder head warping

1) Use a scraper to remove carbon deposits, gasket residue, sealant, oil, carbon deposits, etc. from the contact surface of the cylinder head.

Caution: Do not allow gasket residue, sealant or other foreign particles to enter the oil and water passages.

2) Check the lower surface of the cylinder head for warpage in six directions.

• Warpage Limit: 0.1mm

Valve sizes

Use a micrometer to check the valve dimensions.



Standard valve sizes (mm):

Valve guide clearance

Make this check before removing the valve guide.

Make sure the valve stem diameter is within specifications (see above).

Press the valve approximately 10 mm towards the combustion chamber, swing the valve in different directions and measure the amount of movement using an indicator.



The valve guide clearance is ½ of the indicator reading.

Standard clearance:

• Intake: 0.020 - 0.053 mm
• Issue: 0.040 - 0.073 mm

Maximum clearance:

• Inlet: 0.08mm
• Issue: 0.1 mm

Replacing the valve guide bushing

If you replace the valve guide bushing, replace it with a guide bushing of a larger (by 0.2 mm) repair size.

1) Heat the cylinder head to 110-130'C by placing it in a container with engine oil.



2) Knock out the valve guide bushing from the combustion chamber side using a hammer and punch (special tool).





3) Using a reamer, finish the surface of the hole for the valve guide bushing.

• Standard reamed hole diameter: 10.175-10.196mm

4) Heat the cylinder head to 110-130°C by placing it in a container with engine oil.

5) Use a press to press in the valve guide bushing or hammer it in with a punch (special tool) from the camshaft side.

• Special tool diameter: 6 mm

The installation dimension of the valve guide bushing is shown in the figure on the previous page.



6) Make a ream of the installed valve guide bushing.

• Final standard diameter: 6.000-6.018 mm

Valve seat contact patch

Perform this check to ensure that the valve guides and valves are of proper size.

Apply red lead to the contact surface of the seat and valve and check for uniform valve seat contact.

Make sure the paint print appears all the way around without any breaks.



Otherwise, grind the valve and recheck. If the contact surface is still abnormal, replace the valve seat.

Replacing the valve seat

If the valve seat is removed, replace it with a seat of a larger (by 0.5 mm) repair size.

1) Drill out the old seat until it is destroyed. Drilling should not go deeper than the bottom of the seat recess in the cylinder head. For this purpose, install a drilling depth stop on the drill.



2) Ream the recess for the valve seat of the repair size in the cylinder head.



Standard increased (by 0.5) sizes (mm)



Ream in concentric circles toward the center of the valve guide. This will ensure proper seating of the valve seat.

3) Heat the cylinder head to approximately 110-130°C by placing it in a container with engine oil.

4) Cool the valve seat with dry ice. Press the valve seat into the cylinder head using a drift (special tool).

Caution: Do not touch cold saddles with bare hands.

5) Bring the saddle to the required dimensions by milling.

Attention:

When milling the surface, grasp the tool handle with both hands. Then press the milling cutter against the contact surface along the entire circumference and mill in single passes. If the tool is pressed incorrectly, the valve seat may take a stepped shape.

Process until the dimensions shown in the figure are obtained.

6) Grind the valve using grinding paste.

7) Recheck the valve seating condition.

Valve spring non-squareness

Place the angle on the valve spring and turn it. Measure the maximum gap between the spring and the angle.

The original can be read on the website: nissanbook

• Maximum non-squareness: 2.1 mm

Valve spring dimensions and compression pressure

Measurements are taken using a special valve spring tester.