Disassembly, inspection and assembly of the cylinder head (engine K4M) (Renault Laguna 2)

Removal valve springs

To correctly compress the valve springs, it is necessary to center the plunger of the tool (Mot. 1502) on the valve stem.

The valve spring plate must fit into the bore of the pressure sleeve of the device (Mot. 1502).



Remove:

• crackers;
• valve spring plates
• valve springs
• valves;
• oil seals using pliers (Mot. 1335).

Checking the cylinder head height

Measure the height of the cylinder head.



The height of the cylinder head is 137 mm.

Checking the cylinder head for leaks

Check the cylinder head for cracks using a special device.



Measure the height of the cams.



Height of cams:

• intake: 40.661 ±0.03 mm;
• outlet: 40.038 ±0.03 mm.

Checking the diameters of the bearing journals and bearing holes of the camshafts

Measure the diameter of the camshaft bearings.



Camshaft journal diameter:

• necks No.1, 2, 3, 4, 5 - 24.979-25.000 mm;
• neck No.6 - 27.979-28.000 mm.

Measure the diameter of each camshaft bearing hole.



Diameter of camshaft bearing holes:

• necks N91, 2, 3, 4, 5 - 25.040-25.061 mm;
• neck No.6 - 28.040-28.061 mm.

Checking the axial movement of the camshafts

Install the camshafts, ensuring they are positioned correctly, and the cylinder head cover.

Tighten in the order shown in the figure to the required torque:

• cylinder head mounting bolts 13-20-22-23 (8 Nm);
• cylinder head cover sprinkling bolts 1-12, 14-19 and 21-24 (15 Nm).

Loosen the cylinder head cover mounting bolts 13-20-22-23.

Tighten the cylinder head cover sprinkling bolts 13-20-22-23 (15 Nm) in the specified order to the specified torque.



Secure the magnetic stand to the cylinder head using the mounting plate of the tool (Mot. 588), tightening it with the oil separator mounting bolts and spacers having the following dimensions:

• outer diameter 18 mm;
• bolt hole diameter 89 mm, height 15 mm.

Check the axial movement, which should be within 0.080-0.178 mm.

Remove the cylinder head cover and camshafts.

Checking the valves

The diameter D of the valve stem is measured at a distance X1.



Inlet valves X1: = 75 mm, J = 0.35 mm, D = 5.470-5.485 mm.

Exhaust valves X1: = 77 mm, J = 0.35 mm, D = 5.456-5.471 mm.

Valve head diameter D:

• intake valves - 32.7±0.12 mm
• exhaust valves - 27.96±0.12 mm.

Valve length L:

• intake valves - 109.32;
• exhaust valves - 107.64 mm.

Working chamfer angle A:

• inlet and outlet valves - 45-45-45°

Head thickness T:

• inlet valves - 1.15 mm;
• exhaust valves - 1.27 mm.

Valve stroke:

• intake valves - 9.221 mm;
• exhaust valves - 8.075 mm.

Checking the clearance between the valve stems and guide bushings.

Checking the clearance between the valve stems and the valve guide is done in two ways

Method 1: Raise the valve head by 25 mm, then measure the valve movement with an indicator in the direction of the arrows at an angle of 90° to the camshaft. Half of the obtained value is equal to the value of the gap between the stem and the valve guide.



Method 2: Measure the valve stem diameter and the inside diameter of the valve guide.

The clearance between the valve guide and the valve stem is calculated by subtracting the two measured diameters.



Nominal clearance:

• for intake valves - 0.015-0.046 mm;
• for exhaust valves - 0.029-0.062 mm.

Checking valve springs

Check the spring deviation from the vertical, which should not exceed 1.2 mm.



Check the spring calibration. Spring length under load.

• under a load of 18-20 N the length of the spring is 34.50 mm;
• under a load of 56.3-81.7 N, the spring length is 24.50 mm;
• the length of the spring in a free state is 41.30 mm.

Cylinder head assembly

Insert the valve into the cylinder head.



Place the tip of the tool (Mot. 1511) on the valve stem (the inner diameter of the tip must be equal to the diameter of the rod).



Keep the valve pressed against the seat.



Install the oil seal (not oiled) on the tip.

Slide the oil seal until it meets the frost tip.



Remove the tip.



Install the mandrel onto the oil seal.

Note: The inside diameter of the mandrel must match the diameter of the valve stem. In addition, the bottom of the mandrel must partially rest against the oil-deflecting cap, which serves as a support washer for the valve spring.

Press the valve stem seal into place by tapping the top of the mandrel with the palm of your hand until the valve stem seal contacts the cylinder block counter.



Repeat the above operations for all valves.

Install the springs and spring plates.



[Text published on the website RENAULTBOOK]

Insert the croutons using curved tongs.

Install the thermostat assembly with a new gasket onto the cylinder head.

Tighten the thermostat block mounting bolts on the cylinder head in the order shown in the figure to the required torque (10 Nm).


Install the intake manifold with a new gasket.

Tighten the exhaust manifold mounting stud nuts to the required torque (23 Nm) at the front shown in the figure.



Install the exhaust manifold heat shield. Tighten the exhaust manifold heat shield splinter bolts to the specified torque (21 Nm).

Caution: Make sure the exhaust manifold heat shield is securely fastened between the oxygen sensor and the manifold (to avoid overheating, which could result in damage to the upstream oxygen sensor wiring).

Tighten the oxygen sensor to the specified torque (4.5 Nm) using the tool (Wot. 1495). Install the spacer of the inner timing case.

Install the injector housing linings with a new gasket.

Install the oxygen sensor. Align the injector housing lining with the cylinder head (from the timing drive side).



Align the mating planes of the injector housing linings with the cylinder head.

Tighten the injector housing gasket mounting bolts in the specified order to the required torque (21 Nm).