Signs of a defective cylinder head gasket are:
- loss of engine power
- low coolant level, white exhaust smoke when the engine is hot
- coolant in engine oil. The oil level does not decrease, but rather increases. Gray oil in the engine, foam on the oil dipstick. Oil liquefaction.
- engine oil in the coolant, decreasing oil.
Attention: In this case, after the repair, it is necessary to remove the radiator and flush it with "Solvethane", to remove any remaining oil from the radiator.
- strong seepage of the coolant.
- lack of compression in two adjacent cylinders.
Withdrawal
Disconnect the ground wire from the battery.
Attention: When the battery is disconnected, the information in the electronic memory devices, such as the engine trouble memory or the radio security code memory, is erased. When disconnecting the battery, follow the instructions in section "Removing and installing the battery".
Raise the car.
Remove the front muffler pipe from the exhaust manifold.
Drain the coolant from the engine by unscrewing the drain plug on the side of the engine block under the exhaust manifold. After draining, immediately screw on the plug and tighten it.
Disconnect the water hoses from the thermostat, after loosening the clamps.
Disconnect the throttle cable from the throttle lever.
Remove the oil filler cap.
Lever out the small plugs -arrows- with a screwdriver and remove the bolts underneath. Remove 2 plastic trims from cylinder head.
Unscrew the earth jumper from the front side of the cylinder head.
Disconnect the ventilation fitting of 2 cylinder heads, while lifting the bar on the fitting with a screwdriver.
Unscrew bolt 3 and pull sensor out of cylinder head.
Unscrew 2 bolts 1 and pull the connector upwards. Note the position of the rubber pads for subsequent installation.
On each ignition coil, pull up the metal clip 2 and disconnect the connector, see illustration. Remove the connector block along with the wires.
Unscrew ignition coils and remove from cylinder head. Note the position of the ground jumpers for later installation.
Disconnect the following hoses and connectors from the throttle body. It is advisable to mark the hoses and wires and their connection points before disconnecting, so as not to confuse them during subsequent installation. Release the hose clamps, compress the fixing brackets of the connectors. 1 throttle switch connector, 2 air temperature sensor connector, 3 throttle body heater water hoses, 4 fuel tank vent hose, 6 fuel feed hose (white fitting), 7 fuel return hose (black fitting).
Caution: Fire hazard, do not smoke. Wipe up leaking fuel with a cloth.
Disconnect the idle air control valve hose from the underside of the intake pipe.
Caution: The locking tabs break easily. The connection point is not visible from above, the figure shows the view of the inlet pipe from below.
Unbolt intake pipe support.
Unbolt intake manifold from cylinder head.
Caution: Do not allow any objects to enter the inlet. Objects not removed can cause severe engine damage.
While pressing the wire clamps, disconnect the connectors. 1 temperature sensor, 2 temperature gauge sensor, 3 oil pressure switch, 4 idle air control valve.
Unscrew the cylinder head cover.
Attention: Pay attention to the location of the rubber pads under the bolts for subsequent installation.
Remove the cable channel from the front of the thermostat by pulling out the side clips.
Remove cover.
Set the engine to the top dead center of cylinder 1. To do this, engage 5th gear and move the vehicle forward on level ground or turn the crankshaft pulley in the direction of engine rotation until the camshafts of the intake and exhaust valves of the first cylinder (from the drive chain) will be directed towards each other. The arrows on the sprockets of both camshafts must point upwards.
Lock crankshaft at top dead center with BMW tool 11 2 300 or other suitable pin. To do this, insert the rod through the hole in the engine block into the hole in the flywheel.
Release models prior to August 1992
Remove the lifting eye and gear box top cover. Note the position of the centering sleeves of both outer bolts for subsequent installation. Remove the gasket, which must be replaced.
Loosen both valve cover screws.
Press down the upper chain tensioner and secure in this position with the BMW special tool.
Unscrew the chain sprockets and remove them together with the chain.
Release models since September 1992 (with VANOS)
Unscrew the oil pipe of the VANOS actuator and close with a clean plug.
Disconnect the VANOS actuator solenoid valve connector.
Remove plugs from actuating element.
Loosen the exhaust camshaft sprocket bolts.
Press down the upper chain tensioner and secure in this position with the BMW special tool.
Release nuts and remove VANOS adjustment unit.
Loosen the intake camshaft sprocket bolts. Remove spacer from sprocket.
Remove both sprockets from the camshaft together with the chain.
Remove upper chain tensioner bracket.
Unscrew the tensioner from the cylinder head.
Attention: Hold the tensioner, it is under the action of the spring.
Remove the chain guide, then remove the exhaust camshaft sprocket.
Attention: Attach the chain to the wire hook so that it does not fall down.
Remove 2 bolts -arrows-.
Loosen cylinder head bolts in several passes from inside to outside. A special wrench is required to loosen the bolts, e.g. BMW 11 2 250.
Attention: After removal, do not place the cylinder head on the contact surface, otherwise fully open valves may be damaged. Therefore, the cylinder head should be placed on 2 wooden blocks.
Installation
Before installing, clean the cylinder head and cylinder block from the remnants of the old seal. Do not allow seal residues to enter cylinder bores.
Check that the centering sleeves -arrows- are intact and correctly seated. Threaded holes must be free of oil.
Attention: Be sure to install new cylinder head bolts. Washers are not supplied in standard cylinder heads as they are pressed in. When installing a new cylinder head, install the spacer washers without pressing them in.
Check for cracks on the cylinder head and scratches on its surface.
Measure the flatness of the cylinder head and engine block with a steel ruler in the longitudinal and transverse directions and, if necessary, mill (service station work). The maximum allowable flatness is 0.03 mm.
Attention: With a milled cylinder head, it is possible, depending on the height of the cylinder head after machining, to install a cylinder head gasket either in the original thickness or 0.3 mm thicker (See table 1). Installing a thicker gasket prevents the combustion chamber from shrinking.
Thoroughly clean the holes in the cylinder head from oil and other objects.
Attention: Oil must not remain in the blind holes, otherwise the bolts will not fully tighten the cylinder head, although they will be tightened to the correct torque. In addition, the motor block may crack.
Be sure to replace the cylinder head gasket. Apply a new gasket without sealing compound so that the holes do not overlap.
Lock the camshafts in the correct position using the BMW tool shown. If required, turn the camshafts using 24 mm hexagons.
Attention: Do not damage the camshafts. If necessary, grind the outer sides of the key so that it becomes narrower.
In this case, the camshaft must be so that the valves of the 1st and 6th cylinders move, to do this, first turn the crankshaft by about 30°from the top dead center position and only then turn the camshaft back, this prevents the valves from touching pistons.
Table 1
Tighten the cylinder head bolts in three passes each time in sequence 1 to 14:
- 1st pass: tighten the bolts in sequence 1 to 14 with a torque wrench to a tightening torque of 30 Nm.
- 2nd pass: Tighten the bolts with a rigid wrench by 90°.
- 3rd pass: Tighten the bolts with a rigid wrench by 90°.
Caution: Be very careful when tightening the cylinder head bolts. Before tightening the bolts, check the accuracy of the torque wrench. In addition, a protractor, such as HAZET 6690, is required to tighten the cylinder head bolts. If a protractor is not available, place the key on the bolt head, attach a square to the key handle and mark the desired angle with chalk. Subsequently, turn the key handle in one pass to the line marked with chalk.
Slide the sprocket onto the camshaft flange. The arrow on the star should point up. The threaded holes should be located on the left side of the slots, since when installing the tensioner, the sprocket must turn to the left.
Install the chain guide and upper chain tensioner.
Models since August 1992: Install top chain with sprockets, arrows on sprockets must point up. Do not tighten the sprocket bolts yet.
Release models since September 1992 (with VANOS)
Screw special tool BMW 11 3 390 into the thread of the tensioner. This tool presses on the chain and tightens it slightly so that the camshaft sprockets are centered in 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 upper sprocket chain, making sure it is in the correct position: the flat side of the intake camshaft sprocket is facing outward and the boss is towards the camshaft.
The arrow on the exhaust camshaft sprocket must point up. Bolts should be located in the middle of the slots.
Place spacer on intake camshaft and tighten.
Screw on 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.
Before installing, press VANOS toothed shaft with hydraulic piston 1 back as far as it will go in direction of housing 2.
Install the VANOS adjustment unit so that the toothed shaft engages with the sprocket. If necessary, turn the sprocket anti-clockwise slightly to engage the toothed shaft. Move the VANIS adjustment unit towards the cylinder head, the sprocket turns to the left. Help this movement by pushing the sprocket with your hand.
Screw on the VANQS adjustment unit. Coat the surface joints between the cylinder head and the VANOS adjustment unit with a liquid seal "Drei Bond 1209".
Unload upper tensioner by removing special tool 11 3 290.
Tighten the tensioner by turning the clamping bolt of the tool with a tightening torque of 1.3 Nm.
In this position, tighten the exhaust camshaft sprocket bolts evenly in two passes to a torque of 20 Nm.
Remove the camshaft fixing and chain tensioning tools.
Attention: At BMW workshops, the function of the VANOS device is then checked using special tools. If after installation there are no comments for the operation of the device. this check can be omitted, otherwise contact a BMW Dealership.
Screw on the oil pipe of the VANOS unit with new gaskets. Connect electrical connector.
Screw in the lower tensioner with a new ring with a tightening torque of 35 Nm. In doing so, observe the installation position. The slot on the piston must be vertical. When installing, relieve the upper tensioner.
Models before August 1992: Only now 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, do not forget to put the bushings on both outer bolts.
Install 2 valve cover screws.
Remove the tool that fixes the camshafts.
Install the cylinder head cover and intake pipe in reverse order. Replace damaged gaskets. When applying the outer gasket of the cylinder head cover, pay special attention to the correct position of the cutouts on the front side of the cylinder head.
Tighten cylinder head cover bolts evenly to 10 Nm.
Insert ignition coils with paper gaskets and screw down.
Connect the ignition coil connectors and secure with metal clips.
Connect the throttle cable to the throttle lever.
Connect all water, fuel and vacuum hoses and secure with clamps.
Connect electrical wires.
Screw on cylinder head covers.
Screw the front muffler pipe to the exhaust manifold.
Attention: Pull out the locking rod to set the top dead center.
Fill with coolant.
Check engine oil level, top up if necessary. If the cylinder head was removed to replace a blown cylinder head gasket, it is recommended to change the oil with an oil filter change, as coolant may have entered the oil.