Withdrawal
On engines equipped with a fuel injection system, relieve pressure in the fuel system.
Disconnect the ground wire from the battery. If the battery is located in the engine compartment, remove it.
Remove the air filter assembly.
Disconnect wiring from distributor (if necessary, label all wires) and high voltage wires from the ignition coil.
Disconnect the wire from the coolant temperature sensor.
Disconnect the fuel lines from the fuel line depending on the model.
Drain the liquid from the cooling system.
Tag then disconnect any remaining hoses from throttle body, intake manifold and cylinder head (depending on the model).
Disconnect the throttle cable from the throttle linkage.
Disconnect the exhaust manifold from the cylinder head.
On some engines, it may be necessary to disconnect the manifold from the exhaust pipe.
Remove or disconnect any remaining hoses or tubes from the intake manifold, including the vacuum ignition timing hose and the coolant and heater hoses.
Remove the intake manifold. Do not disconnect or remove components of the fuel injection system unless absolutely necessary.
Remove the fan drive belt and the fan itself.
Remove the valve cover and gasket. Where present, remove the separate semi-circular rubber seal located at the front of the cylinder head.
Set the piston of the first cylinder to TDC on the compression stroke. Remove the drive chain.
Attention: To speed up the procedure, without removing the chain, you can remove the camshaft sprocket and tie it to the body with a piece of wire. Make sure the wire maintains tension on the chain, otherwise the chain may slip off one of the sprockets.
Loosen the cylinder head bolts a quarter of a turn in the reverse order of tightening. Do not disassemble or remove the rocker assembly at this stage.
Remove the cylinder head. Do not wring it out with a screwdriver inserted between the head and the cylinder block, because. this is when
leads to damage to the contact surfaces. Instead, insert a blunt rod into the inlet and gently depress the head.
Remove all remaining external parts from the cylinder head. Cylinder head maintenance procedures are described in the next section.
Installation
The contact surfaces of the head and cylinder block must be perfectly clean.
Use a scraper to remove all traces of carbon and old sealant from them, then clean the contact surfaces with a suitable solvent. While working on the block, fill the cylinders with clean rags to keep dirt out. Remove loose dirt with a vacuum cleaner.
Inspect the contact surfaces of the cylinder block and head for nicks, deep scratches or other damage. If the damage is small, it can be removed with a file; if it is serious, the surface must be re-sanded.
The minimum height of the cylinder head from the contact surface of the valve cover to the lower contact surface of the cylinder head is 128.6 mm. Thus, a layer of metal up to 0.3 mm in comparison with the original height can be removed from the surface of the cylinder head. For heads restored in this way, repair gaskets are produced, which are 0.3 mm thicker than usual. The installation of such a gasket will compensate for the decrease in head height. Gaskets are marked for the M30 engine - 3.0; 3.0E; 3.2E. After grinding the cylinder head, it is necessary to process the end cover.
Clean the bolt holes in the cylinder block with a suitable screw plug, then blow them out with compressed air. Be sure to remove not only dirt from the holes, but also oil and water.
It is recommended to replace the cylinder head bolts, but if you still decide to reuse the old ones, hold each bolt in a vise and drive a lerk through it to remove corrosion and restore the threads. Dirt, corrosion, sealants, damaged threads will not allow you to tighten the bolts with the required tightening torque.
If the bolts or their threads are damaged, install a new set of bolts.
Install all items removed from the head prior to cleaning and inspection.
Make sure the contact surfaces of the head and cylinder block are clean. Place the gasket on the cylinder block with the manufacturer's stamp facing up (usually this is the inscription UP, OBEN or something similar). Use block dowel pins to position gasket properly.
Carefully install the head on the cylinder block. Use the dowel pins to position it correctly.
Install the cylinder head bolts.
Tighten the cylinder head bolts in sequence shown to the correct torque in five steps.
- 1st reception - puff 60 nm;
- 2nd appointment - wait 20 minutes;
- 3rd reception - tighten the bolts by 33°;
- 4th reception - warm up the engine for 25 minutes;
- 5th trick - tighten the bolts by 35°.
Turning bolts to a certain angle
Note that on engines, the final tightening step is done after the engine has warmed up to normal operating temperature (those. it needs to run for a while).
Then install in the reverse order of removal. Adjust the valve clearances before installing the valve cover (check them again after the engine has warmed up). Start the engine and check the system for leaks.
Possible malfunctions of a head of cylinders