Cylinder head of gasoline engines of the M52 series — removal and installation

Withdrawal

Disconnect the ground wire from the battery.

Attention: This erases information about faults in electronic memory devices.

Raise the vehicle.

Remove the front silencer pipe from the exhaust manifold.

Drain the engine coolant by removing the drain plug on the side of the engine block under the exhaust manifold.

Disconnect the water hoses from the thermostat by first loosening the clamps.

Disconnect the throttle cable from the throttle lever.

Remove the oil filler cap.

Remove the small plugs with a screwdriver and unscrew the bolts located under them. Remove the two plastic covers from the cylinder head.


Turn away from the forward party of a head of cylinders a jumper of weight.

Disconnect the cylinder head ventilation fitting by lifting the bar on the fitting with a screwdriver.

Turn away a bolt and pull out the gauge from a head of cylinders.

Loosen the two bolts and remove the block. Mark the position of the rubber pads for later installation.

On each ignition coil, pull up the metal clip and disconnect the connector. Remove the connector block along with the wires.

Unscrew the ignition coils and remove them. Mark the position of the ground jumpers for later installation.

Disconnect the following hoses and connectors from the throttle valve pipe, having previously marked them and the attachment points. After loosening the hose clamps, remove the fixing brackets of the connectors:

• throttle switch connector;
• air temperature sensor connector;
• throttle body heating water hoses;
• fuel tank ventilation hose;
• fuel supply hose (white fitting);
• fuel return hose (black fitting).

Disconnect the idle air control valve hose from the underside of the intake pipe.

Caution: The locking tabs break easily.

Loosen the intake pipe support.



Disconnect the intake manifold from the cylinder head.

While pressing the wire clamps, disconnect the connectors.



Remove the cylinder head cover.




Loosen the side clips and remove the cable duct from the front of the thermostat.



Open the cover.



Set the piston of the first cylinder to the top dead center position. To do this, engage the fifth gear and turn the crankshaft pulley in the direction of engine rotation until the camshaft cams of the intake and exhaust valves of the first cylinder (from the drive chain) will face each other. In this case, the arrows on the asterisks of both camshafts must be directed upwards.


Lock the crankshaft at top dead center. To do this, insert the rod through the hole in the engine block into the hole in the flywheel.



Early model years

Remove the lifting eye and gear box top cover. Mark the position of the centering sleeves of both outer bolts for later installation. Remove the gasket, which must be replaced.



Loosen both valve cover bolts.

Press the upper chain tensioner and fix it in this position with the tool.



Having unscrewed the fastening bolts, remove the chain sprockets together with the chain.



Models of later years of release (with VANOS)

Unscrew the oil pipe of the VANOS actuator and plug it with a plug.



Disconnect the VANOS actuator solenoid valve connector.



Unscrew the plugs from the actuating element.

Loosen the exhaust camshaft sprocket bolts.

Press the upper chain tensioner and fix it in this position with the tool.



Having unscrewed the fastening nuts, remove the VANOS adjustment unit.



Loosen the intake camshaft sprocket bolts. Remove spacer from sprocket.



Remove both sprockets from the camshafts along with the chain.

Remove the upper chain tensioner bracket.



Remove the tensioner from the cylinder head.

Attention: Hold the tensioner, it is under the action of the spring.

Remove the chain guide and exhaust camshaft sprocket.

Attention: Secure the chain to the wire so that it does not fall.

Loosen the cylinder head bolts in several steps from the inside out and remove the cylinder head.

Installation

Check the integrity and correct installation of the centering sleeves.



Lock the camshafts in the correct position with a tool. If necessary, turn the camshafts using 24 mm hexagons.

Attention: Be careful not to damage the camshafts.

In this case, the camshaft must be installed so that the valves of the 1st and 6th cylinders move, to do this, turn the crankshaft first by about 30°from the top dead center position and only then turn the camshaft back. This prevents the valves from touching the pistons.

Tighten the cylinder head bolts in three steps each time in sequence 1 to 14.

• Step 1: Tighten the bolts in sequence 1 to 14 with a torque wrench to a tightening torque of 30Nm.
• Step 2: Tighten the bolts with a 90°hard wrench.
• Step 3: Tighten the bolts with a 90°hard wrench.

Slide the sprocket onto the camshaft flange. In this case, the arrow on the asterisk should point up. The threaded holes must be located on the left side of the slots, since the sprocket must turn to the left when the tensioner is installed.



Install the chain guide and upper chain tensioner.

Early model years

Install the upper chain with sprockets, the arrows on the sprockets should point up. Do not tighten the sprocket bolts yet.

Models of later years of release (with VANOS)

Screw the fixture into the thread of the tensioner. At the same time, the device presses on the chain and pulls it a little so that the camshaft sprockets are installed in the middle of the slots. With some experience, such a device can be made independently. Without a tool, correct installation of the chain is impossible.



Insert spacer and tighten bolts to 20 Nm.



Install the top sprocket chain with the flat side of the intake camshaft sprocket facing out and the boss towards the camshaft.



The arrow on the exhaust camshaft sprocket must point up. The bolts should be in the middle of the slots.



Slide the spacer onto the intake camshaft and tighten.

Install the exhaust camshaft sprocket without tightening the bolts.

Before installing the VANOS adjustment unit, turn both sprockets in the slots to the right as far as they will go.

Press the VANOS toothed shaft with hydraulic piston back before installation (1) all the way in the direction of the hull (2).





Install the VANOS adjustment unit, making sure the toothed shaft engages with the sprocket. If required, turn the sprocket counterclockwise slightly to engage the toothed shaft. Move the VANOS adjustment unit towards the cylinder head, the sprocket must turn to the left.



Screw on the VANOS adjustment unit. Coat the surface joints between the cylinder head and the VANOS adjustment unit with sealant.



Tighten the tensioner by turning the clamping bolt of the tool with a tension force of 1.3 Nm.



In this position, evenly tighten the exhaust camshaft sprocket bolts to 20 Nm in two steps.

Remove the camshaft and chain tensioner.

Fix the oil pipe of the VANOS unit with new gaskets. Connect the electrical connector.

Fix the lower tensioner with a new ring with a tightening torque of 35 Nm. In this case, the slot should be vertical.



Early model years

Tighten the sprocket bolts crosswise to 20 Nm.

Install the gear box top cover with a new gasket. At the same time, tighten the M6 bolts to a torque of 10 Nm, and the M8 bolts to a torque of 22 Nm. Install bushings on both outer bolts.

Install the two valve cover bolts.

Remove the fixture fixing the camshafts.

Install the cylinder head cover and intake pipe.



Tighten the cylinder head cover bolts evenly to 10 Nm.

Insert the ignition coils with paper gaskets and secure them.

Connect the ignition coil connectors and secure with metal clips.