Cylinder head, inlet and exhaust manifolds - removal, separation and refitting

Engine in-car repair procedures / Cylinder head, inlet and exhaust manifolds - removal, separation and refitting

Removal
1 Select a solid, level surface to park the vehicle upon. Give yourself enough space to move around it easily.

2 Refer to Chapter 11 and remove the bonnet from its hinges - this will give extra working space and clearance when lifting off the head.

3 Disconnect the battery negative cable and position it away from the terminal. Note: If the vehicle has a security coded radio, check that you have a copy of the code number before disconnecting the battery cable; refer to Chapter 12 for de tails.

4 With reference to Chapter 1, carry out the following :
a) Drain the engine oil.

b) Drain the cooling system, 5 Refer to Chapter 1 and remove the auxiliary drivebelt(
6 With reference to Section 2 set the engine to TDC on cylinder No 1.

7 With reference to C h a p t e r 3 , slacken/remove the clips and disconnect all coolant hoses from the ports on the cylinder head and thermostat housing.

6 Where applicable, refer to Chapter 4C and unplug the Lambda sensor cabling from the main harness at the multiway connector.

9 With reference to Chapter 5B and Chapter 1, carry out the following: a) Remove the HT leads from the spark plugs and the distributor.

b) Remove the distributor from the cylinder head.

10 On multi-point fuel-injected models, refer to Chapter 4B and remove the throttle body, the fuel rail and the fuel injectors.

11 On single point fuel-injected models, with reference to Chapter 4A, remove the air cleaner and throttle body. Disconnect the manifold pre-heater cabling at the connector.

12 With reference to Sections 6, 4 and 5 , carry out the following: a) Remove the camshaft cover.

b) Remove the timing be/t outer covers, then relieve the tension from the timing belt and disengage it from the camshaft sprocket.

c) Remove the camshaft sprocket.

13 Slacken and withdraw the retaining screws and lift off the inner timing belt cover.

Note that the coolant pump securing bolts double up as fixings for inner timing belt cover - refer to Chapter 3 and remove the coolant pump from the cylinder block, 14 With reference to Chapter 4A or B as applicable, unplug the wiring harness from the coolant temperature sensor at the connector.

15 Refer to Chapter 4C and remove the bolts separate the exhaust down pipe from the exhaust manifold flange.

16 Where applicable, detach the warm air inlet hose from the exhaust manifold heat shield.

17 Slacken and remove the bolt securing the engine oil dipstick tube to the cylinder head.

18 Following the sequence shown in the accompanying illustration IN REVERSE, progressively slacken the cylinder head bolts, by half a turn at a time, until all bolts can be unscrewed by hand (see illustration).

9.18 Cylinder head bolt TIGHTENING sequence

19 Check that nothing remains connected to the cylinder head, then lift the head away from the cylinder block; seek assistance if possible, as it is a heavy assembly, especially if it is being removed complete with the manifolds. If the head sticks, grasp either manifold and rock the head back and forth lightly, until it becomes free. Do not lever between the cylinder head and block, as the mating surfaces may be damaged.

26 Remove the gasket from the top of the block, noting the position of the locating dowels. If the dowels are a loose fit, remove them and store them with the head for safekeeping.

The gasket cannot be re-used, but do not discard it at this point - it may be needed for identification purposes, when purchasing a new gasket
21 If the cylinder head is to be dismantled for overhaul refer to Chapter 2B.

Manifold separation
22 Inlet manifold removal and refitting is described in Chapter 4A or B as applicable.

23 Progressively slacken and remove the inlet and exhaust manifold retaining nuts/bolts. Lift the manifolds away from the cylinder head and recover the gaskets.

24 Ensure that the mating surfaces are completely clean, then refit the manifolds, using new gaskets. Tighten the retaining nuts to the specified torque (see illustrations).

9.24a Fitting new exhaust. . .

9.24b . . . and inlet manifold gaskets

Preparation for refitting 25 The mating faces of the cylinder head and cylinder block/crankcase must be perfectly clean before refitting the head. Use a hard plastic or wood scraper to remove all traces of old gasket and carbon; also clean the piston crowns. Take particular care during the cleaning operations, as aluminium alloy is easily damaged. Also, make sure that the carbon is not allowed to enter the oil and water passages - this is particularly important for the lubrication system, as carbon could block the oil supply to the engine’s components. Using adhesive tape and paper, seal the water, oil and bolt holes in the cylinder block/crankcase.

26 Check the mating surfaces of the cylinder block/crankcase and the cylinder head for nicks, deep scratches and other damage. If slight, they may be removed carefully with abrasive paper, but if excessive, machining may be the only alternative to renewal.

27 If warpage of the cylinder head gasket surface is suspected, use a straight-edge to check it for distortion. Refer to Part B of this Chapter if necessary.

26 Check the condition of the cylinder head bolts, and particularly their threads, whenever they are removed. Wash the bolts in suitable solvent, and wipe them dry. Check each for any sign of visible wear or damage, renewing any bolt if necessary. Measure the length of each bolt, to check for stretching (although this is not a conclusive test, if all bolts have stretched by the same amount). Volkswagen do not actually specify that the bolts must be renewed, however, it is strongly recommended that the bolts should be renewed as a complete set whenever they are disturbed.

29 On all the engines covered in this Chapter, it is possible for damage to be caused by the piston crowns striking the valve heads, if the camshaft is rotated with the timing belt removed and the crankshaft set to TDC. For this reason, the crankshaft must be set to a position other than TDC on cylinder No 1, before the cylinder head is refitted: use a wrench and socket on the crankshaft pulley centre bolt to turn the crankshaft in its normal direction of rotation, until all four pistons are positioned halfway down their bores, with piston No 1 on its upstroke -i.e. 90° before TDC.

Refitting
30 Lay a new head gasket on the cylinder block, engaging it with the locating dowels.

Ensure that the manufacturers “TOP” and part number markings are face up (see illustrations).

9.3Oa Lay a new head gasket on the cylinder block, engaging it with the locating dowels

9.30b The gasket part number should face upwards

31 With the help of an assistant, place the cylinder head and manifolds centrally on the cylinder block, ensuring that the locating dowels engage with the recesses in the cylinder head. Check that the head gasket is correctly seated before allowing the full weight of the cylinder head to rest upon it.

32 Apply a smear of grease to the threads, and to the underside of the heads, of the cylinder head bolts; use a good-quality highmelting point grease.

33 Carefully enter each bolt into its relevant hole (do not drop them in) and screw in, by hand only, until finger-tight.

34 Working progressively and in the sequence shown, tighten the cylinder head bolts to their Stage 1 torque setting, using a torque wrench and suitable socket (refer to illustration 9.18). Repeat the exercise in the same sequence for the Stage 2 torque setting.

35 Once all the bolts have been tightened to their Stage 2 settings, working again in the given sequence, angle-tighten the bolts through the specified Stage 3 angle, using a socket and extension bar. It is recommended that an angle-measuring gauge is used during this stage of the tightening, to ensure accuracy. If a gauge is not available, use white paint to make alignment marks between the bolt head and cylinder head prior to tightening; the marks can then be used to check that the bolt has been rotated through the correct angle during tightening. Repeat the exercise for the Stage 4 setting.

36 Refit the coolant pump with reference to Chapter 3.

37 Refit the timing belt inner cover, tightening the retaining screws securely. Refer to Section 5 and refit the camshaft sprocket.

38 Refer to Section 2 and follow the procedure for setting the engine to TDC on No 1 cylinder with the timing belt removed. On completion, refer to Section 4 and refit the camshaft timing belt.

39 The remainder of refitting is a reversal of the removal procedure, as follows: a) Bolt the engine dipstick tube bracket to the timing belt cover, where applicable.

b) Refer to Chapter 4C and reconnect the exhaust downpipe to the exhaust manifold.

c) On multipoint fuel-injected systems, refer to Chapter 4B and refit the fuel injectors, fuel rail and the throttle body.

d) On single point fuel-injected models, refer to Chapter 4A and refit the throttle body and air box. Reconnect the in/et manifold pre-heater wiring.

e) Refer to Chapter 5B and refit the distributor and the ignition HT leads.

f) Refer to Section 6 and refit the camshaft cover.

g) Reconnect the radiator, expansion tank and heater coo/ant hoses, referring to Chapter 3 for guidance. Reconnect the coo/ant temperature sensor wiring.

h) Refer to Chapter 7 and refit the auxiliary drivebelt(s)
i) Restore the battery connection.

j) Refer to Chapter 11 and refit the bonnet.

40 On completion, refer to Chapter 1 and carry out the following: a) Refill the engine cooling system with the correct quantity of new coolant.

b) Refill the engine lubrication system with the correct grade and quantity of oil.