Fiat Uno Manual
Cylinder head - removal and refitting (1116 cc and 1301 cc engines)Engine / Cylinder head - removal and refitting (1116 cc and 1301 cc engines)
1 Drain the cooling system (see Chapter 2).
2 Disconnect the battery.
3 Disconnect and plug the carburettor fuel hoses.
4 Disconnect the throttle and choke linkage from the carburettor.
5 Disconnect the HT leads from the spark plugs.
6 Disconnect the brake servo vacuum hose from the intake manifold.
7 Disconnect the coolant hoses from the thermostat housing.
8 Disconnect the crankcase ventilation system hoses from the rocker cover and carburettor.
9 Unbolt and remove the timing belt cover.
10 Release the timing belt tensioner pulley bolt, then lever the pulley against the spring plunger and retighten the bolt to retain the tensioner pulley in the non-tensioned position.
Slip the belt from the camshaft sprocket.
11 Disconnect the coolant hoses from the carburettor and intake manifold.
12 Disconnect the exhaust downpipes from the manifold.
13 If a crowfoot type wrench is available, the cylinder head nuts and bolts can be removed and the complete cylinder head camshaft carrier assembly withdrawn (photo).
29.13 Using a crowfoot type wrench on a cylinder head bolt
14 If this type of wrench is not available however, remove the carrier first as described in Section 27.
15 If a crowfoot is available, unscrew the cylinder head nuts and bolts evenly and progressively starting with the centre ones and working towards both ends.
16 Rock the cylinder head by gripping the manifolds. Note: Do not insert a lever in the gasket joint to prise the head from the block.
17 Pull the head off the studs and remove it to the bench. Remove and discard the old cylinder head gasket.
18 Unbolt and remove the hot air collecting shield for the air cleaner from the exhaust manifold. The exhaust and inlet manifolds can now be unbolted. The carburettor may remain on the inlet manifold.
19 Overhaul and decarbonising of the cylinder head is described in Section 39.
20 Refitting is a reversal of the removal process, but make sure the crankshaft and camshaft timing marks are set as described in Section 28 to avoid the valve heads digging into the piston crowns when the head is refitted.
21 Always use new gaskets. The cylinder head gasket must be fitted (ALTO visible) so that the oil pressure hole in the block is central in the copper ringed cut-out in the gasket (photos). Make sure that the gasket surfaces on head and block are perfectly clean and free from oil, otherwise the heat sealing (polymerisation) process of the gasket cannot take place.
29.21A Cylinder head gasket top face marking
29.21B Cylinder head gasket in position - cylinder block drain plug arrowed
29.21C Lowering cylinder onto block
22 Tighten the cylinder head nuts and bolts to the specified torque, in the sequence shown in Fig. 1.30. Follow the procedure very carefully owing to the special type (ASTADUR) of gasket used which hardens in use. Always keep a new cylinder head gasket in its nylon cover until just before it is required for use.
23 Oil the cylinder head bolts and washers and allow them to drain for thirty minutes.
24 Tighten the bolts in the following
Stage 1 20 Nm (15 lbf ft) Stage 2 40 Nm (30 lbf ft) Stage 3 Through 90º Stage 4 Through 90º (photo) Retightening the bolts after a running-in mileage is not required.
29.24 Tightening a cylinder head bolt through 90º using a protractor
25 Fit the timing belt (Section 28).
26 Check the valve clearances (Section 26) after the camshaft carrier has been fitted (Section 27).
27 Bolt on the camshaft carrier cover.
28 Reconnect all hoses, leads and controls.
29 Reconnect the battery and refill the cooling system.
Fig. 1.30 Cylinder head bolt tightening sequence (Sec 29)