Opel Omega B 2.0 X20XEV (1994): Cylinder Head Assembly

Part numbers are from the manufacturer's original catalogue. Check them against your VIN before ordering.

• Socket set and ratchet
• torque wrench
• angle gauge for angle tightening
• valve spring compressor
• valve stem seal installer
• micrometer and bore gauge
• dial indicator with stand
• straightedge and feeler gauge
• valve lapping compound
• camshaft pulley holding tool
• sealant for oil grooves
• clean shop rags
• engine oil for assembly

1. Wash the head thoroughly and clean the oil and coolant passages. Check the mating surface with a straightedge and feeler gauge lengthwise and across. The allowable warpage is minimal (on the order of hundredths of a millimeter); if it is exceeded, have the head resurfaced at a machine shop. Check the head for cracks, especially between the valve seats and around the spark plug wells.
2. Inspect the valve seats and valves: recondition the seats if necessary, and replace valves and guides. Lap the valves to the seats with lapping compound until you get an even, matte contact band, then remove all the compound completely from the ports and valves.
3. Lubricate the valve stems with engine oil and install the valves in their original positions (do not mix them up if you are reusing the old ones). Fit the new valve stem seals with the installer tool, taking care not to damage their lips on the keeper grooves.
4. Install the spring retainers and springs, compress them with the valve spring compressor, and fit the keepers. Tap the end of the valve stem lightly with a hammer through a drift to make sure the keepers have seated correctly. Lubricate the hydraulic lifters and followers with oil and install them in place; if reusing old ones, put them back in their original positions.
5. Lubricate the camshaft journals and lobes with assembly oil. Lay the camshafts in their bearing seats in the position that matches the timing marks. Install new camshaft seals. Apply sealant to the bearing cap mating surfaces only where the design calls for it, keeping it out of the oil passages.
6. Tighten the camshaft caps evenly, in a crisscross pattern, in several passes, to a low torque (about 8-10 N·m (6-7 lb-ft); exact value per the service manual). Check that the camshafts turn freely and check the end play.
7. Prepare the block: clean the surface, remove any remains of the old gasket and any oil or coolant from the head bolt holes, and check the surface with a straightedge. Bring the No. 1 piston to the position where the crankshaft is at the TDC mark by turning it with the pulley bolt. Do not turn the crankshaft or camshafts while the head is removed and the valves could hit the pistons.
8. Place the new head gasket dry, without sealant, with the marking facing up, onto the locating dowels. Set the head on the block. Lubricate the threads and the underside of the heads of the new bolts with engine oil (unless specified otherwise).
9. Tighten the head bolts from the center outward in a spiral pattern, in several stages: first a preliminary torque of about 25 N·m (18 lb-ft), then additional angle tightening steps (usually several stages of 60-90°, with the total angle per the service manual). Head bolts stretch, so they must not be reused. Do not skip stages, and do not use extensions without an angle gauge.
10. Install the intake manifold and exhaust manifold with new gaskets. Tighten the fasteners in a crisscross pattern, with torque per the service manual, usually in the range of 15-25 N·m (11-18 lb-ft) for manifold studs and nuts.
11. Install the camshaft pulleys and the timing belt according to the marks (tension the toothed belt using the method specified in the service manual, usually with the tensioner roller). Lock the marks in place, then turn the crankshaft two full revolutions by hand and recheck that the marks align. If the marks do not align, repeat the installation.
12. Install a new valve cover gasket and spark plug well seals. Tighten the valve cover bolts to a low torque (about 8-10 N·m (6-7 lb-ft)), evenly in a crisscross pattern. Install the spark plugs (torque about 20-30 N·m (15-22 lb-ft)) and the ignition coil or ignition module.
13. Connect the cooling system hoses, sensors, connectors, and vacuum lines. Fill with coolant, bleed the air from the system (through the upper hose or the bleeder), and check the oil level.
14. First start: check the oil pressure and look for leaks, warm the engine up to operating temperature, and watch for stable idle speed. The hydraulic lifters may tick for the first few minutes until they fill with oil. After the engine cools, check the coolant and oil levels. After some driving, it is usual to check again for leaks and for the tightness of the connections.

• Errors when installing the timing belt (being off by one tooth) on a 16-valve engine can cause the valves to hit the pistons and lead to expensive repairs, so check the marks twice
• Replace the head bolts with new ones after removal, and follow the tightening sequence and angles strictly according to the manufacturer's service manual
• If you have no experience working on the timing system and cylinder head, have a repair shop handle the tightening and the valve timing adjustment