Attention: Describes removal for petrol engine. Since, however, not all model variants can be considered, Before removing the cylinder head, it is necessary to check again whether all the wires and other connections going from the head to the head are released. Features that apply to the diesel engine are listed at the end.
Remove the cylinder head only when the engine is cold (at room temperature). Do not remove exhaust pipes and partly also inlet pipes.
A cylinder head gasket defect is identified by one or more of the following symptoms:
- Loss of power.
- Loss of coolant. White exhaust gases when the engine is warm.
- Oil loss.
- The presence of coolant in the engine oil, the oil level does not decrease, but it becomes less. Gray color of engine oil, foamy emulsion on the oil level indicator, liquid oil.
- Engine oil in coolant.
- The coolant boils a lot.
- There is no compression in two adjacent cylinders.
Attention: From 3/95 to engines with the designation AEK, AAM, ADZ, ADY (ABF since 2/ 94), a metal cylinder head gasket and modified cylinder head bolts are installed.. The metal gasket can also be installed on older engines (ABS, 2E), however, in this case, modified bolts -B- are required first of all. These bolts can be recognized by the projections on the heads (arrows). Bolts for the cylinder head of the ABF engine have been changed: -C-. The letter -A- indicates the previously used bolts with a smooth head.
Removing
Disconnect ground wire (-) battery.
Drain coolant, see chapter «Cooling system».
Remove air filter, see chapter «Supply system».
Unbolt alternator support at cylinder head.
Disconnect coolant hoses from cylinder head and intake manifold.
Detach throttle link, do not remove plug retainer.
Attention: Most electrical plug connectors are made with metal clips. Before unplugging, depending on the version, press or compress the clips and thereby release the plug.
Carburetor engines
Disconnect the vacuum hoses from the intake manifold and carburetor. To facilitate subsequent assembly, mark the hoses with tags.
Disconnect the fuel supply line from the carburetor and plug it with a suitable plug.
Disconnect the connectors for the intake manifold heater and the fuel shut-off valve. Loosen the wire tie at the cylinder head cover.
Remove the electrical wires and vacuum hose from the control valve at the carburetor.
Engines with injection systems?
Mono-Jetronic system: unscrew the fuel supply and return lines at the combined injection system and plug the holes with suitable plugs. Remove all electrical wires and vacuum hose from ignition distributor. Remove central injection system, see chapter «Petrol injection system».
Digifant and K-Jetronic systems: unscrew the fuel manifold from the cylinder head and remove the valve injectors from the cylinder head, see chapter «Petrol injection system».
Unscrew exhaust pipe from exhaust connection, see chapter «Exhaust system».
Loosen the toothed belt and remove it from the top of the camshaft, see above.
Mark electrical wires from hydraulic switch and temperature sensor and remove.
Remove spark plug caps.
Disconnect the vacuum hose from the carburetor to the ignition distributor.
To facilitate subsequent assembly, mark the position of the bracket at the cylinder head cover and unscrew it together with the cover. Remove the oil deflector see above.
Loosen the cylinder head cover bolts with a socket wrench (e.g. HAZET990 Slg-12). The bolts must first be loosened 1/2 turn in the indicated sequence, and then completely unscrewed in the same sequence.
Check if all wires and hoses that lead to the cylinder head are disconnected.
Remove the cylinder head and place it on two wooden blocks.
Remove the cylinder head gasket
Installation
Before installing, clean the cylinder head and cylinder block of seal residues with a suitable scraper. When doing this, make sure that dirt does not get into the bores of the cylinder block. Cover holes with rags.
Check for oil in the cylinder head bolt holes. If necessary, insert a clean rag into the holes and collect the oil.
Attention: If oil remains in the holes, the engine block may be damaged when the bolts are tightened.
Check the cylinder head for deflection with a steel ruler.
Check the deflection with a steel ruler and feeler gauge at various points in the cylinder head. The maximum allowable unevenness should not exceed 0.1 mm. (For a 16-valve engine, roughness should not exceed 0.05 mm). The cylinder head of a diesel engine must not be flat ground.
Attention: If the contact surfaces of the cylinder head of a gasoline engine are subjected to finishing, then the permissible height of the refinished head must not be less than a = 132.6 mm.
Cylinder heads with cracks in the intervalve bridge and the first threads for spark plugs can not be repaired and continue to operate if the maximum width of the cracks does not exceed a = 0.5 mm.
The cylinder head gasket must be replaced.
Inscription «oben» (top) on the gasket must face the cylinder head. Lay the cylinder head seal dry and on a dry surface so that the bores in the cylinder block are not obstructed. For a diesel engine, then make sure that a sealing gasket of the required thickness is installed.
To center the cylinder head, prepare guide pins, which can be used as two old cylinder head bolts with sawn heads and slots cut for a screwdriver.
Screw guide pins into holes 8 and 10.
Install the cylinder head.
Insert bolts with washers into the remaining 8 holes and tighten them by hand. The cylinder head bolts must be replaced. Depending on the type of gasket to be installed, use the appropriate cylinder head bolts, see above.
Unscrew the guide pins with a screwdriver, insert the 2 remaining bolts with washers and tighten them by hand.
Caution: Cylinder head bolts must be tightened very carefully. The torque wrench must be checked for accuracy before tightening. The cylinder head bolts must be tightened with a cold engine.
The cylinder head bolts are tightened in 4 steps. In each step, tighten the bolts in sequence from 1 to 10. The following values are valid for all 4-cylinder engines:
- Reception 1: using a torque wrench with a torque of 40 Nm.
- Reception 2: using a torque wrench with a torque of 60 Nm.
- Reception 3: without interrupting the tightening, tighten in the direction of tightening 1/4 turn (90°) with a locked key.
- Reception 4: without interrupting tightening, tighten in the direction of tightening 1/4 turn (90°) with a locked key.
When tightening the cylinder head bolts, evaluate the key angle. Place the wrench handle along the cylinder head and turn it in one move to a position perpendicular to the axis of the head (1/4 turn is 90°).
Attention: For diesel engines built before 9/93, tighten the cylinder head bolts when warm. Tightening the cylinder head bolts on a warm gasoline engine and a diesel engine manufactured since 10/93 is not permitted as part of service or repair.
Install toothed belt, see above.
Attention: When installing another cylinder head with a mounted camshaft instead of the old head, lubricate the contact surfaces of the poppet tappets and cams after installing the cylinder head.
Install the cylinder head cover with oil deflector with new seals and tighten to 10 Nm. For a carburetor engine, install the bracket for the fuel stilling chamber together with the cylinder head cover.
Install the toothed belt guard see above.
Install the generator support.
Engine with injection system: install injection system, see chapter «Petrol injection system».
Carburetor engine: connect the plug connectors of the intake manifold heater and the fuel shut-off valve. Attach the wire tie to the cylinder head cover.
Connect the electrical wires to the carburetor or injection system.
Connect the vacuum hoses to the intake manifold and carburetor as marked. If required, secure the hoses with clamps.
Attach gas traction.
Connect the fuel supply line to the carburetor and secure it with a clamp.
Connect the ignition distributor vacuum hose to the carburetor or Mopo-Jetronic system.
Connect all coolant hoses and secure with clamps.
Connect the electrical wires to the temperature sensor, put on the tips of the spark plugs.
Install air filter, see chapter «Supply system».
Check engine oil level. If the cylinder head seal is defective, change the oil.
Warm up the engine to normal operating temperature, check the coolant level, and check all hose connections for leaks.
Check ignition timing, see chapter «Ignition system».
Check idle adjustment, see chapters «Supply system» and «Petrol injection system».
Removing the diesel engine
Disconnect electrical wires from connectors and glow plugs.
Clean fuel lines between high pressure fuel pump and injectors with cleaning agent and unscrew. Close openings with appropriate caps.
Remove glow plugs and injectors, see chapter «diesel engine».
Installation
Depending on the protrusion of the pistons above the surface of the cylinder block, gaskets of various thicknesses are installed. When replacing the gasket, pay attention to the designation. Install a new gasket only with the same designation. The black arrow points to the location of the spare part number; white arrow - to designation (holes or teeth), if present on the gasket being installed.
Diesel engines built before 9/93: Retighten the cylinder head bolts when the engine is warm. To do this, let the engine warm up and let it idle until the radiator fan turns on (oil temperature over +50°С). Cylinder head bolts, without first releasing and without interrupting tightening, tighten 1/4 turn in the direction of tightening (90°) with a locked key. Pay attention to the tightening sequence, see figure 02-098.
Note: From 10/93 a metal cylinder head gasket is fitted as standard. In this regard, tightening the cylinder head bolts on a warm engine with such a gasket is no longer required.
Install glow plugs, see chapter «diesel engine».
Install injectors, see chapter «diesel engine».
Clean the connection points of the high-pressure fuel lines with a cleaning agent. Tighten union nuts to 25 Nm.
Connect the electrical wires to the fuel switch and glow plugs.
Check the start of injection of the high pressure fuel pump, see chapter «diesel engine».
Diesel engine with a displacement of 1.6 liters and gas turbine supercharging (designation RA/SB): after repairs and a run of approximately 1000 km, the cylinder head bolts must be tightened. Cylinder head bolts without first releasing and without interrupting tightening, tighten in the direction of tightening by 1/4 turn (90°) with a locked key. Pay attention to the tightening sequence, see figure 02-098. Bolts can be tightened when the engine is cold or warm.
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