Removal
Caution! Allow the engine to cool before removing the cylinder head. Use new head mounting bolts when installing.
1. Remove the battery (see the relevant section).
Caution! On models with Opel Anti-Theft System (ATWS), the negative cable must be disconnected from the battery terminal within 15 seconds after the ignition is turned off, otherwise the alarm will be triggered.
2. Remove the wiper arms and water deflector panel (see the relevant section).
3. Remove the complete intake manifold assembly, including its flange (see the relevant section).
4. Drain the cooling system and remove the spark plugs as described in Section 1.
5. Disconnect the wiring connectors from the coolant temperature gauge sensor and the engine management system temperature sensor, which are screwed into the cooling system outlet pipe assembly (see illustration).
6. Loosen the clamps and separate the cooling system hoses from the pipes (see illustration).
7. Unscrew the mounting bolts and remove the exhaust manifold assembly from the cylinder heads. Remove the O-rings and discard them - they are subject to replacement (see illustration).
8. Remove the timing belt as described in Chapter 7.
9. Remove the camshaft sprockets, timing belt tensioner pulley/upper idler pulley assembly and lower idler pulley (see Chapter 8).
10. Remove the water pump as described in Section 3.
11. Unscrew the mounting bolts and remove the inner timing belt cover (see Chapter 6).
Left cylinder head
12. Remove the valve cover as described in Chapter 4.
13. Disconnect the wiring harness connector and the spark plug wires of the right cylinder head from the ignition control module so that the latter can be removed together with the head. Also remove the ground terminal bolts from the rear of the left cylinder head.
14. Remove the relay box cover in the left corner of the engine compartment. Lift the engine control unit (ECU), then release the retaining clip and disconnect the wiring connector (see the relevant section) (see illustration). The ECU can be left in the working position in the box.
15. Follow the wiring harness from the left cylinder head to the relay box in the engine compartment. Release the injection relay connectors from the box, then disconnect the harness connector and release the sealing ring (see illustrations).
16. Disconnect the harness connectors located behind the battery, then the camshaft position sensor and left cylinder head knock sensor connectors. Disconnect the additional harness connectors from the positive battery terminal and move the harness away from the cylinder head. On some models, the harness is connected to the fusible link block instead of the battery terminal. In this case, remove the fusible link and disconnect the wiring from the block (see illustrations).
17. Remove the left front exhaust pipe (see the relevant section).
18. Remove the power steering pump (see the relevant section).
19. Loosen the clamp and separate the upper radiator hose from the pipe on the front side of the left cylinder head.
20. Loosen the bolt and spacer securing the coolant pipe and engine mounting eye to the cylinder head, and remove the mounting eye. Move the pipe to the left to separate it from the thermostat housing, then remove the pipe (see illustrations). Remove the O-rings from the inner end of the tube and discard them - they must be replaced.
21. Remove the oil dipstick, then unclip the dipstick tube from the cylinder block and remove it from the engine. Discard the tube's O-rings - they must be replaced.
22. Remove the exhaust camshaft (see the relevant section).
23. Working in the reverse order of tightening them (see illustration 11.41), gradually loosen the cylinder head mounting bolts (a quarter turn at a time), then unscrew the bolts manually (see illustration). Remove each bolt and washer one at a time.
24. Lift the head from the cylinder block (see illustration). If necessary, tap the head gently with a mallet to separate it. Do not force the head away from the cylinder block under any circumstances, as this will damage the contact surfaces. If the mounting pins are loose, note their location and remove them for safekeeping.
25. Remove the cylinder head gasket - it must be replaced.
Right cylinder head
26. Place a suitable container under the oil filter. Unscrew the filter using a special tool and drain the oil into the container. Replace the filter.
27. Remove the union nuts securing the engine oil cooler tubes to the cylinder block, then remove the banjo bolts securing the tubes to the cooler. Remove the sealing washers from each side of the unions and move the tubes back (see illustrations).
28. Release the clamps and separate the lower radiator hose, expansion tank hose and heater hose from the tube that runs along the right side of the engine. Remove the mounting bolts, then remove the tube from the engine. Discard the O-ring - it must be replaced (see illustrations).
29. Remove the right front exhaust pipe (see the relevant section).
30. Remove the exhaust camshaft (see Chapter 10).
31. Remove the cylinder head as described in points 23-25 (see illustration).
Preparing for installation
32. Clean the mating surfaces of the cylinder head and block. Use a soft scraper to remove all traces of gasket and carbon deposits, and clean the piston crowns as well. Be especially careful with the aluminum cylinder head, as the soft metal is easily damaged. Do not allow dirt to enter the oil and water passages - carbon grains can block the oil supply to the camshaft or crankshaft bearings. Use masking tape and paper to plug the water and oil holes, as well as the bolt holes in the cylinder block. To prevent grains from falling into the gap between the cylinder wall and the piston, apply a small amount of grease to this area. After cleaning the piston, rotate the crankshaft so that this piston moves down and remove the grease from the cylinder with a clean rag.
33. Check the block and head for nicks, deep scratches and other damage. Minor irregularities can be carefully filed down. More serious damage can be repaired by regrinding, but this work should be left to a specialist.
34. If necessary, check the cylinder head for deformation using a ruler. See. Section 2C, if necessary.
35. Make sure the cylinder head bolt holes in the crankcase are clean and remove any oil from them using a syringe or sponge. If there is any liquid or oil left in the holes, the hydraulic pressure that will build up when tightening the bolts will cause the block to crack.
Installation
Left cylinder head
36. Make sure the crankshaft is still at approximately 60° BTDC and wipe the mating surfaces of the head and block.
37. Make sure the mounting pins are in the working position.
38. Install a new head gasket onto the cylinder block with the "OBEN" (or "TOP") mark facing up and toward the front of the engine (see illustration).
39. Carefully install the cylinder head (together with the exhaust manifold), guiding it along the pins.
40. Lightly lubricate the threads and heads of the new cylinder head bolts with engine oil, then carefully insert them into position and tighten them only by hand for now.
41. Working in the sequence shown, gradually tighten all cylinder head mounting bolts to the tightening torque (see illustrations).
42. In the same sequence, tighten each bolt to the required angle (see Specifications). It is recommended to use a corner template to ensure accuracy (see illustration).
43. In the same way, tighten the bolts to the required angle (see Specifications).
44. Repeat this step for Stage 4.
45. Finally, tighten the bolts in the same sequence at the angle.
46. Then install in the reverse order of removal, paying attention to the following:
- a) If the right cylinder head has also been removed, install it before connecting any ancillary components to the block.
- b) Install new O-rings on the dipstick tube and thermostat housing tube. Make sure that the tubes and mounting eye are each in their original position, install the mounting bolt and spacer gasket and tighten the bolt to the torque specified in the Specifications.
- c) Make sure the engine wiring harness is routed correctly and all connectors are connected. Also make sure the ground strap mounting bolts are securely tightened.
- d) Install the camshaft, timing belt and related components as described in Chapters 6-10.
- d) Use new O-rings when installing the coolant outlet pipes to the cylinder heads and tighten the mounting bolts to the tightening torque specified in the Specifications.
- e) Make sure that all cooling system hoses are connected to their corresponding fittings and securely fastened with clamps.
- g) Install the exhaust pipe and intake manifold (see the relevant section).
- c) Finally, fill the cooling system and the power steering fluid reservoir (see the relevant section).
Right cylinder head
47. Install the head as described in points 36-45, remembering that the mark on its gasket ("OVEN" or "TOP") should be facing up and towards the rear of the engine.
48. Then install in the reverse order of removal, paying attention to the following:
- a) If the left cylinder head has also been removed, install it before connecting any ancillary components to the block.
- b) Install a new O-ring onto the coolant pipe and tighten the pipe mounting bolts securely.
- c) Install new sealing washers on the engine oil cooler couplings and tighten the coupling nuts and bolts to the specified tightening torque Specifications.
- d) Install the camshaft, timing belt and related components as described in Chapters 6-10.
- d) When installing the cooling system outlet pipes on the cylinder heads, use new O-rings and tighten the mounting bolts to the specified tightening torque Specifications.
- e) Make sure that all cooling system hoses are connected to their corresponding fittings and securely fastened with clamps.
- g) Install the exhaust pipe and intake manifold (see the relevant section).
- c) Install a new oil filter and fill the cooling system (see the relevant section).
- i) Finally, check the engine oil level (see the relevant section).
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