Removal
Disconnect the ground cable from the battery. Drain the coolant from the cooling system.
Disconnect the air supply line to the turbocharger, the flexible line of the engine crankcase ventilation system from the cylinder head cover and the air supply line between the air filter and the radiator shroud (the line is put on the fittings).
Disconnect all flexible cooling system lines from the cylinder head. Disconnect the brake booster vacuum line and the vacuum pump oil return line. Disconnect the electrical wires from the glow plugs, oil pressure sensor, coolant temperature sensor and radiator fan thermal switch. Disconnect the fuel return lines from the injectors. Disconnect the injection lines from the fuel pump and injectors. Disconnect the vacuum line from the fuel pump. Disconnect the thermostat cover from the cylinder head. Disconnect the fuel lines from the pump and fuel filter. Disconnect the vacuum line from the intake manifold. Disconnect the oil lines from the turbocharger and oil pump. Disconnect the turbocharger from the exhaust manifold. Disconnect the bracket supporting the front exhaust pipe from the transmission crossmember.
Disconnect the oil return line from the turbocharger and engine block. Remove the V-belts of the coolant pump and alternator.
Unscrew the mounting bolt on the left side of the lower timing case.
Unscrew the upper timing case mounting bolt on the right side so that it can be removed. Remove the three spring clips of the upper timing case. Remove the mounting bolts and lower the case down. Remove the inspection hole plug of the crankshaft installation mandrel from the cylinder block at the height of the crankshaft pulley. Turn the crankshaft so that the cutout of the fuel pump pulley is at the 12 o'clock position (see Fig. 2E.11).
Install a mandrel in the cylinder block to set the crankshaft to the TDC position of piston No.1 of cylinder (see Fig. 2E.13).
Rotate the crankshaft counterclockwise until it stops in the mandrel. Remove the timing belt tensioner roller. and then the timing belt.
Remove the passive pulley (increasing the timing belt wrap angle) and the rear timing cover. Unscrew the injectors. Remove the cylinder head cover.
Unscrew the ten cylinder head mounting bolts in the reverse order of tightening (see Fig. 2E.26). Remove the cylinder head.
Disassembly
Remove the intake and exhaust manifolds. Unscrew the two brackets with holes for lifting the engine and the oil pressure sensor from the cylinder head.
Remove the vacuum pump by unscrewing the two mounting bolts in sequence (and at the same angle).
Remove bearing caps No.2 and 4 of the camshaft. Unscrew the nuts of the remaining camshaft bearing caps by 1/4 turn.
Remove the camshaft bearing caps together with the upper liners, seals and take out the camshaft. Remove the tappets together with the valve clearance adjusting plates and arrange them so that during assembly they can be installed in the same cylinder head sockets in which they were previously installed. Remove the vacuum pump drive tappet. Using the device (21.024), compress the springs of the individual valves and remove the crackers. Remove the device and remove the upper spring support plates, springs and valves.
Using special pliers (MS-1501), remove the oil seals from the valve stems.
Examination
After disassembling the cylinder head, you should thoroughly wash all the parts, check their technical condition and assess their suitability for further work. All gaskets should be replaced and the valves should be ground in.
Assembly
Lubricate the valve stems with engine oil and insert them into the guides. Wrap the ends of the valve stems with adhesive tape so that they do not damage the working edges of the caps and use tool 21.007 to install the caps on the valve stems. Install the valve springs, upper plates and use tool 21.024 to compress the springs and insert the crackers.
Lubricate the vacuum pump drive rod with engine oil and insert it into the cylinder head bore. Lubricate the tappets with oil and install them together with the valve clearance adjusting plates into the seats in the cylinder head where they were installed earlier. Insert the lower camshaft bearing shells into the seats in the cylinder head and lubricate them with engine oil. Install the camshaft on the shells, the eccentric at the end of the shaft should be directed upwards.
Install the upper shells into the camshaft bearing caps and lubricate them with oil. Place washers under the cylinder head to allow the valves to move in the guides. Apply SPM-4G911 ZF/G sealing paste to the sealing plane of bearing No.1 of the camshaft (from the valve timing drive side).
Install camshaft bearing caps No.1, 3 and 5. The markings on them (arrows) should be facing forward (towards the timing drive). Tighten the camshaft bearing cap fastening nuts by hand.
Tighten camshaft bearing cap nuts #3, then #1, and then #2 with a wrench by 180°.
Repeat the last operation until the caps are exactly in place. Install bearing caps No.2 and 4 with blows of a plastic hammer. Tighten all camshaft bearing cap bolts to the specified torque. Lubricate the camshaft seal ring with engine oil and install it using tool 21110.
Install the vacuum pump together with the O-ring and tighten its mounting bolts sequentially and evenly to the specified torque.
Screw two brackets with holes to lift the engine to the cylinder head and screw in the oil pressure sensor.
Bolt the exhaust and intake manifolds to the cylinder head, together with new gaskets, and tighten the bolts and nuts securing them to the appropriate torque.
Installing the cylinder head and adjusting the valve timing system
Attention: The mating surfaces of the cylinder block and head gasket must be smooth, clean, without scratches or damage.
Check the condition of the lower surface of the cylinder head; this surface is not repaired (not reground). Before installing the head, make sure that the groove on the end of the camshaft eccentric is installed horizontally (parallel to the lower plane of the cylinder head), and the greater part of the eccentric is directed upwards (see Fig. 2E.25).
Measure the piston protrusion above the top plane of the cylinder block.
Depending on the piston protrusion, select the appropriate thickness of the head gasket. Install the head gasket on the cylinder block so that the side with the inscription "TOP" is on top. Install the head on the cylinder block.
Insert the mounting bolts into the corresponding holes in the cylinder head.
Caution: When installing the cylinder head, use new mounting bolts.
Tighten the cylinder head mounting bolts to the specified torque in the specified sequence (see Fig. 2E.26).
Please note. Since March 1992, 1.8 dm³ engines have used a different type of cylinder head bolts. These have M12 threads and Torx T70 heads. These bolts should be tightened in the same sequence as the old type bolts (see Fig. 2E.26) to the following torques:
- Stage 1: 10 Nm
- Stage 2: 100 Nm
- Step 3: Unscrew bolt "1" by 180°
- Step 4: Tighten bolt "1" to 70 Nm
- Step 5: Tighten bolt "1" an additional 120°
- Step 6: Tighten the remaining bolts in the manner described above (steps 3-5), observing the correct tightening sequence
Screw the glow plugs into the cylinder head, tightening them to the appropriate torque, and connect their electrical wires.
Screw the injectors into the cylinder head together with new thermal insulation washers, with the convex side facing the head.
Install the rear right timing case with the tensioner pulley. Install the rear left case with the middle pulley. Check that the rubber ring of the flexible hose is in the correct place on the case.
Install the camshaft pulley and insert the tool (1. Fig. 2E.27).
Check if the engine crankshaft touches the mandrel at the TDC position of the piston of the 1st cylinder. Install a new timing belt. Tension the timing belt as follows. Loosen the bolt securing the pulley to the camshaft, then unscrew the tensioner roller bolt by half a turn. The tensioner roller will move to the timing belt under the action of the spring. and then tighten all the above bolts. Remove all installation tools.
Turn the crankshaft two full turns in the direction of its working rotation and set it in a position in which the cutout of the fuel pump pulley is at the 12 o'clock position (see Fig. 2E.11).
Turn the crankshaft in the opposite direction and set the cutout of the fuel pump pulley to the 11 o'clock position (see Fig. 2E.11).
Screw the mandrel into the inspection hole of the cylinder block to install the piston of cylinder 1 at TDC and carefully rotate the engine crankshaft (in the direction of its working rotation) until it stops against the installation mandrel.
Insert the camshaft pulley installation tool into the hole provided for it (see Fig. 2E.27).
Loosen the bolts securing the middle pulley and tensioner roller by one turn; then push the section of toothed belt from the opposite side of the tensioner roller in its direction and release the belt.
Tighten all mounting bolts.
Remove all installation tools. Then screw the plug into the inspection hole of the installation mandrel in the engine block. Install the timing cover. Install and tighten the alternator drive V-belt. Install the coolant pump drive V-belt. Connect the turbocharger oil return line to the engine block.
Screw on the front exhaust pipe.
Bolt the exhaust pipe bracket to the transmission crossmember Install new gaskets and connect the oil supply lines to the pump and turbocharger. Connect the vacuum line to the intake manifold, bolted to the fuel pump. Check and adjust the valve clearance if necessary.
Install the cylinder head cover together with the gasket. Then perform the remaining steps in the reverse order of the cylinder head removal process, paying attention to:
- maintaining the appropriate tightening torques for bolts and nuts;
- installing a new thermostat cover gasket.
- removing air from the fuel system.
- filling the cooling system and removing air from it.
- checking the tightness of all connections.