Note. This and the following sections provide recommendations for the repair and maintenance of BMW vehicles «518», «520» And «520»» with 4-cylinder engine, «525» And «528», as well as features of repair and maintenance of the BMW engine «520» And «520i» with 6-cylinder engine, «525i», «528i» And «535i», except for which checks, adjustments and repairs are carried out in the same way as the above models.
Removal of a head of cylinders is made on the cold engine.
Drain the liquid from the cooling system. If the system is flooded with antifreeze, drain it into a container for later use.
Model cars «518», «520»
Disconnect the crankcase ventilation hose from the cylinder head cover.
Remove the air filter assembly (on the model «518» the filter is mounted on a vertical carburetor; on the model «520» the filter is installed on the side of the horizontal carburetors; on models with a fuel injection engine, the filter is connected with a horizontal hose).
Disconnect two hoses 2 and 3 (see photo) hot coolant supply, disconnect wire 4 from the coolant temperature indicator sensor.
Remove the bolts securing the oil dipstick bracket and its tube.
Disconnect the fuel supply hose from the fuel pump.
Disconnect the power cable from the starter and remove it from the mounting eye.
Disconnect the throttle control link from the carburetor.
Disconnect the intake manifold heating hose, remove the bundle of electrical wires from the mounting brackets under the manifold.
Notes. On a fuel injected engine, unscrew the fuel lines from the fuel pump housing and lay them aside. Disconnect the hose from the fitting on the distribution flange, disconnect the electrical wire from the temperature sensor.
Disconnect the vacuum hose and cooling system hoses from the intake manifold.
Disconnect the wire from the oil pressure sensor and the low voltage wire from the ignition distributor. Take out wires from holders on a head of cylinders.
Disconnect the power wires from the carburetor electric starter and from the electromagnetic shut-off valve, take the wires down.
Disconnect the muffler intake pipe from the exhaust manifold.
Remove the cylinder head cover and the upper timing cover.
Remove the ignition distributor cap, disconnect the wires from the spark plugs.
Install the piston of the 1st cylinder (counting from the drive side of the timing mechanism) and TDC, aligning the ignition distributor rotor with the mark on its housing, and the mark on the bottom cover of the timing mechanism drive with the second mark on the crankshaft pulley.
Remove the chain tensioner plunger while holding the spring, which is compressed with considerable force, from falling out.
Loosen and remove the camshaft drive sprocket mounting bolts.
Remove the camshaft drive sprocket together with the chain in a forward motion.
Gradually loosen the cylinder head mountings in the reverse order of tightening, remove the cylinder head.
Models «525» And «528»
Remove the air filter assembly and cylinder head cover.
Disconnect hoses 1 and 2 (see photo), disconnect wire 3 from the coolant temperature gauge sensor, remove bracket 4.
Disconnect the vacuum hose 5 from the intake manifold, disconnect the power wires from the carburetor electric starter and from the temperature sensor. Loosen screw 6 a few turns.
Disconnect the fuel supply hose from the fuel pump, disconnect the throttle control rod and the bundle of wires for powering the carburetor starter.
Disconnect the intake manifold heating hoses. Disconnect the wire from the oil pressure sensor. Disconnect the coolant inlet and outlet hoses from the cylinder head and from the carburetor starter cover.
Remove the timing gear top cover and chain tensioner plunger while holding the spring in place.
Loosen and remove the camshaft drive sprocket mounting bolts.
Remove the camshaft drive sprocket with chain towards the front of the engine.
Disconnect the muffler intake pipe from the exhaust manifold.
Loosen the cylinder head bolts gradually in the reverse order of tightening. Install guide pins (shown by arrows in the photo) in order to prevent movement or tension of the axes of the rocker arms.
Remove the cylinder head, head gasket, clean the mating surface of the cylinder head by plugging the threaded holes.
From model year 1978 on BMW «525», «528» And «528i» Removal of the cylinder head must be carried out taking into account the following:
Engines with Zenith 32/40 and 35/40 INAT carburetors with starting aid
Disconnect the wire from the negative terminal of the battery and the wire from the clamping coil.
Disconnect wire 1 (see photo) from the coolant temperature sensor.
Disconnect hoses 2 and 3 of the cooling system.
Disconnect the wires 4 from the electromagnetic shut-off valves, disconnect the plug connector 5 of the starting devices, the connector 6 of the thermal time relay, disconnect the ground wire 7 and the wire from the oil pressure sensor.
Disconnect the fuel supply hose 9 from the fuel pump, the coolant supply hose 10 to the auxiliary starting device and the vacuum hose 11 from the check valve.
Disconnect the coolant inlet and outlet hoses 12 and 13 from the intake manifold and cylinder head.
Disconnect the hose 14 of the cooling system from the intake manifold, disconnect the throttle control rod 15.
Remove the bundle of electrical wiring from the mounting brackets.
Remove the bolt securing the oil dipstick bracket.
Engines with Solex 4А1 carburetor
Disconnect the wire from the coolant temperature sensor and disconnect the TDC sensor connector.
Disconnect the fuel hoses 3 and 4, the cable 5 and disconnect the throttle control rod 6 from above and below.
Disconnect hoses 7 and 8 of the cooling system and disconnect connectors 9 and 10.
Disconnect hoses 11 and 12 of the cooling system, vacuum hose 13, ground wire and wire from the oil pressure sensor.
Disconnect the electrical wires from the temperature sensor and remove the bundle of wires from the holders. Fuel injected engines.
Disconnect the wire from the negative terminal of the battery, disconnect the connector 1, remove the clamp 2.
Remove the cylinder head cover.
Disconnect the spark plug wires, remove the ignition distributor cap.
Disconnect the pads from the injectors.
Disconnect the wire from the coolant temperature sensor and ground wire 3.
Disconnect the throttle control rod 4 at the top and bottom.
Disconnect connector 5 of the throttle switch.
Disconnect the hose 6 of the cooling system and remove the clamp 7.
Disconnect the wires from the oil pressure sensor.
Disconnect hoses 8 and 9 of the cooling system, disconnect the TDC sensor connector.
Disconnect the fuel supply hose 10 and the fuel outlet hose 11, as well as the vacuum hose 12 and the hose 13 of the cooling system.
Disconnect wire 14.
Disconnect the outlet and inlet hoses of the interior heating system.
Disconnect wires 17 and 18 and pull the bundle of wires up through the opening of the intake manifold.
Remove the bundle of wires from the holders (see arrow in the photo).
Disconnect the inlet pipeline from the 6th cylinder.
Disconnect the muffler pipes from the exhaust manifolds and from the transmission clamp.
Remove the air filter.
Drain the coolant.
Loosen the fan shroud mounting bolts and hang it over the fan.
Turn away bolts of fastening of the fan and take out it upwards together with a casing.
Disconnect hoses and electrical wires.
Disconnect the fuel supply and drain pipes, electrical wires and vacuum hoses from the carburetor.
Disconnect the throttle control linkage.
Disconnect the coolant inlet and outlet hoses from the carburetor.
Disconnect the brake booster vacuum hose and interior heater hose.
Disconnect high-voltage wires from a cover of the distributor of ignition and remove a cover.
Turn out a bolt of a tension lath of a belt of a drive of the generator.
Remove the alternator drive V-belt.
Remove the front bolt 12 (see photo) generator bracket.
Remove the alternator bracket.
Remove the TDC sensor from the holder.
Remove the spark plugs from the cylinder head sockets.
Set the piston of the 1st cylinder to the TDC position, while the rotor of the ignition distributor must match the mark on the distributor housing.
Remove the camshaft drive belt cover by pushing it up.
Loosen the idler pulley mounting bolts, move the idler pulley towards the engine and secure it in this position.
Remove the toothed belt from the camshaft pulley. After that, do not turn the crankshaft of the engine.
If the toothed belt is to be used again, mark the direction of travel on it.
Remove the cylinder head cover, remove the spring washers.
Move the compensation tube down and fix it with tool 111290.
Remove the cylinder head.
