DOHC Engine Cylinder Head (Sierra)

DOHC Engine Cylinder Head Assembly

Removal the cylinder head

1. Disconnect the ground wire from the battery.

2. Remove the air filter together with its pipes.

3. Drain the cooling system by unscrewing the bolt at the bottom right of the radiator.

4. Disconnect the upper flexible pipe from the radiator, the pipe from the expansion tank and the pipe from the thermostat.

5. Disconnect the flexible heating line of the vehicle interior from the cylinder head.

6. Disconnect the air bleed pipes from the cylinder head cover.

7. Disconnect the accelerator pedal cable. In a carburetor engine, unscrew the throttle cable together with the holder, and in a fuel-injected engine, disconnect the rod from the throttle body after removing it from the side of the clamp made of artificial material.

8. On fuel injected engines, disconnect the vacuum line from the intake manifold.



9. On fuel-injected engines, disconnect the fuel supply lines to the pressure regulator and to the injectors.

10. Disconnect the high tension wire from the ignition coil.

11. Unscrew the nut securing the upper front exhaust pipe to the exhaust manifold.

12. Raise the car.

13. Unscrew the other two nuts securing the front exhaust pipe to the exhaust manifold.

14. Lower the car.

15. Unscrew the high-tension wires from the spark plugs and remove the distributor cap (Torx T25 key).

16. Unscrew the spark plugs.

17. Remove the ignition distributor.

18. Remove the cylinder head cover (11 bolts and 4 nuts).

19. Remove the upper cover of the cardan shaft of the timing chain.

20. Unscrew the two Torx bolts securing the camshaft sprockets.

21. Set the piston of the 1st cylinder to TDC.

22. Use a scriber to mark the relative positions of the sprocket teeth and the chain interacting with them.

23. Remove the upper chain guide.

24. Remove the tensioner axle retaining ring and chain tensioner (see Fig. Installing the valve timing of a DOHC engine).

25. Remove the chain tensioner axle using an M6x70 bolt and a 15 mm long sleeve.

26. Remove the chain tensioner.

27. Remove the sprockets from both camshafts.

28. Remove the hydraulic tensioner plunger.

29. Remove the camshaft bearing caps by gradually unscrewing the bearing caps and oil supply pipe caps one by one.

Caution: Bearing caps are marked at the factory to ensure proper placement during assembly.

30. Remove the camshafts.

31. Remove the hydraulic tappets and mark them so that they will fit into place during assembly.



32. Loosen the cylinder head mounting bolts by half a turn in the reverse order to the tightening process (see Fig. DOHC engine cylinder head bolt tightening sequence), and then unscrew the cylinder head mounting bolts.

Caution: The bolts must not be reused to secure the cylinder head.

33. Remove the cylinder head together with the intake and exhaust manifolds. After removing the head from the cylinder block, do not lay it on its lower surface.

DOHC Engine Cylinder Head Bolt Tightening Sequence

M11 bolts – tightening sequence: 1 – 10.



M8 bolts – tightening sequence: 11 – 13.

Installing the cylinder head

1. Clean the gasket mating surfaces on the cylinder head and engine block.

2. Install a new head gasket on the cylinder block.



3. To eliminate the possibility of damage to valves and pistons, rotate the crankshaft and set the piston of the 1st cylinder to a position approximately 20 mm below TDC.

4. Install the head onto the engine cylinder block.

5. Screw the bolts into the holes in the cylinder head by hand (see Fig. DOHC Engine Cylinder Head Bolt Tightening Sequence).

6. Tighten the bolts in the sequence shown in Fig. DOHC Engine Cylinder Head Bolt Tightening Sequence, Five Steps:

• Stage 1 (M11 bolts – sequence 1 – 10): 25 Nm;
• Stage 2 (M11 bolts – sequence 1 – 10): 55 Nm;
• Step 3 (M11 bolts – sequence 1 – 10): tighten by 90°;
• Step 4 (M11 bolts – sequence 1 – 10): tighten by 90°;
• Stage 5 (M8 bolts – sequence 11 – 13): 24–27 Nm.

Attention! Two long M8 bolts are screwed into the holes marked as (11) and (12), and the short M8 bolt is screwed into the hole (13).

7. Lubricate the surfaces of the hydraulic tappets with a thin layer of oil and install them in the appropriate places in the cylinder head sockets.

8. Lubricate the sliding surfaces of the camshaft bearings on the cylinder head and install the camshafts on them so that the keyways on the front side are directed to the right.

9. Install the bearing caps, paying attention to their markings:

• R1–R5 – intake valve shaft bearing caps (R1 – from the valve timing drive side);
• L1–L5 – exhaust valve shaft bearing caps (L1 – from the valve timing drive side).

10. Insert the oil supply lines to the cams and the upper guide of the cardan chain of the valve timing system.

11. Tighten the camshaft bearing cap bolts to the appropriate torque, alternately, in the order corresponding to their numbers.



12. Disassemble the hydraulic tensioner pusher and drain the oil from it.

13. Using special tool 21.145, assemble the hydraulic pusher of the tensioner, filled with engine oil. To do this, install the pusher housing with the flat side on the workbench, and the sleeve of the tool with the cone facing up. Install the piston of the pusher on the sleeve and squeeze everything together with the lever of the tool, which makes a characteristic sound after pressing to the stop (in the lowest position).

14. Position the hydraulic pusher of the chain tensioner in the guide.

15. Install the chain tensioner and its retaining ring.

16. Check whether the piston of the 1st cylinder is at TDC (the groove of the keyway of the crankshaft is directed downwards).

17. Install the two camshaft sprockets together with the chain, observing the correct mutual arrangement in accordance with the marks made during the process of removing the sprockets.

18. Perform several revolutions of the crankshaft in the direction of its working rotation, and then check the correct mutual arrangement of the shafts and the chain.

19. Install the top guide together with the spring clip.

20. Install the upper timing chain cardan housing with a new gasket.

21. Install the cylinder head cover with a new gasket.

22. Tighten the cylinder head cover mounting bolts to the appropriate torque, starting from the outer bolts and ending with the middle ones.

23. Screw in the spark plugs.

24. Install the ignition distributor, rotor and distributor cap.



25. Connect high voltage wires to the spark plugs and ignition coil.

26. Screw the front exhaust pipe to the exhaust manifold together with a new gasket.

27. Connect the wires to the radiator fan motors and the wire harness to the electronic control unit.

28. On a fuel-injected engine, connect the fuel lines to the pressure regulator and injectors.

29. Connect the vacuum lines.

30. Connect the accelerator pedal cable.

31. Connect the air bleed system pipes to the cylinder head cover.

32. Connect the flexible heating pipe for the vehicle's interior to the cylinder head.

33. Connect the upper flexible hose to the radiator, the hose to the expansion tank and the thermostat.

34. Install the air filter.

35. Add oil to the engine lubrication system and fill the cooling system with the appropriate fluid and bleed air from it.

36. Connect the ground wire to the battery.

37. Check the engine idle speed settings.

Repair of valve seats and valves

1. If the measurement results show that after regrinding the valve working chamfers will meet the requirements, they can be repaired in a specialized repair shop. In this case, it is also necessary to order regrinding of the corresponding valve seats.

2. Check the condition of the valve working chamfer.

3. Check the condition of the working chamfer of the valve seats.

4. Check the tightness of the valve-seat assembly.

5. Very thoroughly clean the cylinder head after re-grinding the seats and lapping the valves from particles of abrasive material and metal filings.

Assembly

1. Lubricate the valve stems with oil.

2. Insert the valve into the guide it was previously running in, seal the grooves on the end of the valve stem with tape.

3. Install the lower valve spring support plate.

4. Lubricate the working edge of the valve stem seal with oil and insert it using the appropriate mounting sleeve.

5. Remove the adhesive tape.

6. Repeat the last four operations for the remaining valves.

7. Install the corresponding springs, upper spring support plates and crackers on each valve in turn using a valve spring compressor.

8. Screw the exhaust and intake manifolds to the cylinder head.