Cylinder head, front (2-4-6)
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Cylinder head, front (2-4-6)
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Warning
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The camshafts must not be rotated because the valves could touch the pistons or each other and become damaged. The crankshaft may only be turned between 0° and 60° BTDC when the camshafts of both cylinder heads are locked with locking tools.
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1.
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Drape the wings with protective covers, drain the radiator of coolant and disconnect the negative cable from the battery.
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2.
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Raise the car and remove the two bolts securing the front exhaust pipe to the exhaust manifold.
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3.
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Lower the car and remove the air cleaner and the mass air flow sensor.
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4.
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Remove the engine covers.
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5.
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Remove the intake manifold and lift it up. Plug the holes with paper. Then disconnect:
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the hose from the fuel pressure regulator
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the secondary air injection vacuum hose (where fitted).
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the IAC valve connector
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the TCS throttle body connector
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the coolant hoses to the throttle body
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the hose from the EVAP canister purge valve. Lift away the intake manifold.
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6.
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Disconnect the fuel lines and plug the connectors.
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7.
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Remove the bolts securing the centre intake manifold complete with fuel rail and place it to one side.
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8.
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Remove the gasket to obtain access to all the retaining bolts for the lower section of the intake manifold. Remove the lower section and plug with paper.
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9.
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Unplug the electrical connectors, the coolant hose and remove the coolant bridge.
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10.
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Remove the ignition coil, disconnect the HT leads and take out the spark plugs. Undo the bracket for the ignition coil, camshaft position indicator and oxygen sensor connector and put it to one side.
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11.
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Disconnect the upper radiator hose at the engine. Remove the lifting eye.
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12.
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Slightly loosen the bolts securing the crankshaft pulley. Remove the multigroove drive belt, the belt tensioner, the power steering pump pulley, the coolant pump pulley and the cover.
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13.
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Remove the right-hand front wheel and the cover in the wheel housing. Remove the crankshaft pulley (undo the six bolts but do
not
remove the centre bolt).
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14.
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Put the No. 1 cylinder in the compression position. The markings on the camshaft sprockets and timing cover should be aligned as should the markings on the crankshaft. Place the locking tools for the camshaft sprockets on the cylinder heads.
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15.
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Before removing the toothed belt,
mark its direction of rotation
. To facilitate refitting, the belt can be marked at both the camshaft marking and at the crankshaft marking.
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16.
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Release the belt tension and remove the toothed belt.
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17.
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Turn the crankshaft back 60° BTDC.
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18.
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Remove the bracket securing the upper adjusting pulley and the tensioning pulley. Remove the valve cover. Ensure that the O-rings are in place and that they do not fall into the engine.
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19.
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Remove the cylinder head camshaft sprockets and remove the two timing cover bolts from the cylinder head. The camshaft sprockets are marked 3 and 4.
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Warning
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The open ended wrench used as a holding tool to remove the camshaft sprockets must not have jaws that are too long. There is a risk of damaging the casting so that the tappet locks.
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20.
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Remove the bearing caps on the exhaust camshaft.
It is important to finish removal at the bearing cap where the valve tappets are under load. Pay attention to the marking on the bearing caps. Slacken the bolts in stages, 1/2 to 1 turn at a time. Remove the camshaft seal and lift out the camshaft.
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Note
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The intake camshaft need not be removed when removing the cylinder head.
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21.
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Undo the cylinder head bolts in the order shown. First slacken them a 1/4 turn and then 1/2 a turn. Lift off the cylinder head. Be careful when putting it down as the intake camshaft is still in place and the valve stems could be bent accidentally.
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22.
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Remove the intake camshaft, the valve depressors, the oxygen sensor holder, the exhaust manifold and the heat shield.
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1.
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Make sure that the crankshaft is positioned at 60° BTDC.
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2.
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Clean all contact surfaces and position the gasket. Note the guides for the gasket and that it is marked OBEN/TOP.
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3.
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Fit the exhaust manifold, the valve depressors, the heat shield and the oxygen sensor holder.
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4.
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Place the cylinder head in position. Use new bolts. Tighten in the order shown.
Tightening torques
Stage 1: 25 Nm (18.5 lbf ft)
Stage 2: Tighten to 90°
Stage 3: Tighten to 90°
Stage 4: Tighten to 90°
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5.
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Place the camshafts in position and lubricate them
generously
with oil. Make sure that the locating pins are in position as shown.
Pay attention to the markings on the bearing caps and in the cylinder head. Smear flange sealant, part No. 93 21 795, sparingly on the surfaces of the front bearing caps that are in contact with the cylinder head.
Fit the bearing caps and tighten the bolts in the order shown. Tighten them in stages, 1/2 to 1 turn at a time.
Turning torque 8 Nm (6 lbf ft).
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6.
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Lubricate the sealing lips and fit the gasket (using tool 83 94 959) and camshaft bolt and washer.
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7.
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Fit the two timing cover retaining screws in the cylinder head.
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8.
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Check that the locating pins are correctly positioned.
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9.
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Fit the camshaft sprockets correctly in relation to the locating pins, as shown.
Tightening torque 50 Nm (37 lbf ft) + 60.
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Warning
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The jaws of the open-end wrench used as a holding tool when fitting the camshaft sprockets must not be too long as they might damage the casting and cause the tappet to jam.
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10.
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Fit locking tool 83 95 006 on the No. 1, No. 2, No. 3 and No. 4 camshaft sprockets.
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11.
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Turn the crankshaft to just before top dead centre and fit locking tool 83 95 006 on the crankshaft. Carefully turn the crankshaft in the direction of engine rotation until the arm rests against the coolant pump's flange and tighten it.
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12.
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Fit the toothed belt according to the marked direction of rotation. Use setting tool 83 95 006 to keep the belt in place and adjust the tensioning roller loosely by hand to prevent the belt from jumping off. Adjust anticlockwise.
Fit a section of the toothed belt and fit tool 83 94 985 to measure the belt tension.
Lightly tighten the centre bolts of the adjusting rollers. Adjust the lower adjusting roller anticlockwise to a belt tension of 275-300 Nm.
Turning torque 40 Nm (30 lbf ft).
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Important
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The adjustment of the belt tension is
only
a preparatory measure and
must not
be used as a check when the belt is finally adjusted.
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13.
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Adjust the tensioning pulley with an allen wrench until the two marks are aligned. Tighten.
Tightening torque 20 Nm (15 lbf ft).
Remove the locking tool for camshaft sprockets 1 and 2. Then adjust the upper adjusting roller until camshaft sprocket No. 2 moves 1-2 mm clockwise.
Turning torque 40 Nm (30 lbf ft).
Remove the upper locking tool.
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14.
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Turn the engine over two revolutions until just before the zero mark and place the locking tool on the crankshaft. Carefully turn the crankshaft in the direction of engine rotation until the arm rests against the coolant pump's flange and then tighten the arm. Fit setting tool 83 95 006 and check that the markings on the camshaft sprockets are aligned with the markings in the tool.
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Important
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Also check the tensioning roller to ensure that the marks are in alignment.
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15.
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Fit the timing cover.
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16.
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Check that the O-rings are in place in the valve cover and wipe clean. Lubricate with soapy water and apply 87 81 841 in the corners by the camshaft bearing caps. Fit the valve cover.
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17.
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Fit the lifting eye and the upper radiator hose.
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18.
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Fit the ignition coil bracket, the camshaft position indicator, the ignition coil and fit the oxygen sensor connector in its holder. Refit the spark plugs and connect the HT leads.
Turning torque, spark plugs 25 Nm (18.5 lbf ft).
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19.
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Fit the crankshaft pulley.
Tightening torque 20 Nm (15 lbf ft).
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20.
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Fit the coolant pump pulley, the power steering servo pump pulley, the belt tensioner and the multigroove belt.
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21.
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Fit the right-hand front wheel and the cover in the wheel housing.
Turning torque, wheels
110 Nm (81 lbf ft)
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22.
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Fit the coolant bridge with 74 96 284 on the bolts. Refit the coolant hose and electrical connectors.
Turning torque 30 Nm (22 lbf ft).
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23.
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Fit the lower intake manifold complete with new gasket. See drawing for tightening order. Lock the bolts with 74 96 268.
Tightening torque 20 Nm (15 lbf ft).
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24.
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Fit the middle intake manifold with a new gasket and fuel rail. Remove the protective tape. Lock the bolts with 74 96 268.
Tightening torque 20 Nm (15 lbf ft).
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25.
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Fit the fuel lines.
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26.
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Fit the intake manifold. First fit:
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the hose to the evaporative (EVAP) emission canister air purging valve
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the coolant hoses to the throttle body
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the TCS throttle body connector
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the IAC valve connector
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the secondary air injection vacuum hose (where fitted).
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the hose to the fuel pressure regulator in front of the butterfly.
Tighten all bolts at the mating surface. Begin with the bolts in the middle and continue alternately towards the ends.
Tightening torque 20 Nm (15 lbf ft).
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27.
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Fit the air cleaner and the mass air flow sensor and bolt down the front exhaust pipe. Fit the engine covers.
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Important
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It is very important that all the joints in the exhaust system are sealed.
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28.
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Reconnect the negative cable to the battery. Remove the covers protecting the wings.
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29.
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Top up with coolant and check the system for leaks.
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30.
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Check other oil and fluid levels and top up if necessary. Check that the engine, engine bay and cabin are clean.
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Warning
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The coolant is very hot and under high pressure. When the pressure cap is opened there is a danger of scalding. Take great care.
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31.
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Bleed the cooling system as follows:
Fill the system up to the MAX level, fit the pressure cap, start the engine and warm it up (preferably at different rpm) until the radiator fan starts. Remove the pressure cap and top up to the MAX level again.
Fit the pressure cap and run the engine at varying rpm until the radiator fan starts three more times.
Switch off the engine and top up to the MAX level, if necessary.
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32.
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Drive the car on the road and check all functions.
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