Fiat Uno Manual

Timing belt - renewal (1116 cc and 1301 cc engines)
Engine / Timing belt - renewal (1116 cc and 1301 cc engines)


1 Set No. 4 piston at TDC. Do this by turning the crankshaft pulley nut or by jacking up a front roadwheel, engaging a gear and turning the wheel until the mark on the flywheel is opposite to the TDC mark on the flywheel bellhousing aperture. Remove No. 4 spark plug, place a finger over the plug hole and feel the compression being generated as the crankshaft is rotated and the piston rises up the cylinder bore.

2 On some models the TDC marks on the crankshaft pulley and belt cover may be visible and can be used instead.

3 Remove the alternator drivebelt (Chapter 2, Section 8). Unbolt and remove the timing belt cover.

4 Check that the timing mark on the camshaft sprocket is aligned with the pointer on the belt cover backing plate (photo).

28.4 Camshaft sprocket alignment marks
28.4 Camshaft sprocket alignment marks

5 Slacken the nut in the centre of the tensioner pulley and push in on the support to release the tension on the belt, then retighten the nut. Slide the drivebelt off the pulleys.

6 Check that the crankshaft and camshaft pulleys have not been moved from their previously aligned positions.

7 To check that the auxiliary shaft sprocket has not moved, take off the distributor cap and check that the contact end of the rotor arm is aligned with No. 4 HT lead contact in the cap.

8 Fit the new belt. Start at the crankshaft drive pulley and, taking care not to kink or strain the belt, slip it over the camshaft pulley.

The camshaft may have to be turned slightly to mesh the pulley with the teeth on the belt.

Fit the belt on the tensioner pulley last; if this is difficult, do not lever or force the belt on, recheck the belt (photo).

28.8 Slipping timing belt onto tensioner pulley
28.8 Slipping timing belt onto tensioner pulley

9 Release the tensioner nut and rotate the crankshaft through two complete revolutions.

Retighten the nut. The belt tension may be checked by twisting it through 90º with the finger and thumb. It should just turn through this angle without undue force. Note: The above procedure serves only as a rough guide to setting the belt tension - having it checked by a FIAT dealer at the earliest opportunity is recommended.

10 Refit the timing belt cover (photo).

28.10 Tightening timing belt cover nut
28.10 Tightening timing belt cover nut

Fit and tension the alternator drivebelt (Chapter 2, Section 8).

Fig. 1.28 TDC marks (1) at front of engine (Sec 28)
Fig. 1.28 TDC marks (1) at front of engine (Sec 28)

Fig. 1.29 Timing belt arrangement (Sec 28)
Fig. 1.29 Timing belt arrangement (Sec 28)

1 Camshaft sprocket
2 Tensioner pulley locknut 3 Timing mark on crankshaft front oil seal retainer 4 Crankshaft sprocket
5 Crankshaft sprocket timing mark 6 Auxiliary shaft sprocket 7 Tensioner bracket bolt 8 Tensioner pulley
9 Timing belt
10 Tensioner bracket
11 Tensioner spring


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