Fiat(SOFIM) Timing Belt Replacement 2.5 Diesel Engine Fig 01. View of timing mechanism
( 1 ) Protective panel ( 2 ) Tensioning roller ( 3 ) Securing nut ( 4 ) Tensioning plunger ( 5 ) Tensioning roller ( 6 ) Injection pump sprocket ( 7 ) Timing belt
Replacement of Timing Belt The timing belt should be changed every 70,000 miles, even if it appears to be in good condition. Serious engine damage can result if the belt snaps during the operation of the engine. When a belt is replaced, follow the instructions given step by step to obtain the correct timing setting. The valves; could hit the piston crowns if the timing is out of "phase". Always make sure to order the correct timing belt. Special timing pins (No. Mot. 910) are required to set the timing. Fig, 01. shows an exploded view of the timing mechanism and should be referred to for the following operations. The numbers in subsequent illustrations are the same as shown in the exploded view. To remove the timing belt proceed as follows: • Remove all parts in front of the timing cover to expose the timing mechanism. • Remove the protective shield (1) from the engine.
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• Apply a socket or a ring spanner to the crankshaft pulley bolt and turn the engine until the piston of No. 1 cylinder is at the T.D.C. position. To find the exact position of the top dead centre. refer to Fig. 02. to align the mark "A" in the camshaft sprocket and the mark "B" in the cylinder head cover. The latter is a small boss. The glow plugs can be removed to facilitate the rotation of the engine, as the cylinders are then free of compression.
Fig. 02. Aligning the timing marks at the back of the camshaft sprocket (A) and the cylinder, head cover (B). • Prevent the engine from rotating and slacken and remove the crankshaft pulley bolt. remove the pulley by inserting two tyre levers behind the pulley at opposite points and pry off the pulley. A gear can be engaged to lock the crankshaft. • Unscrew the timing belt cover, noting its attachment in Fig. 01. • Insert a screwdriver, as shown in Fig. 03. and push the tensioning roller (2) towards the lefthand side, Slacken the nut (3) and at the same time compress the plunger (4) with the screwdriver, until it protrudes on the other side. Tighten the nut (3) with the roller (2) in the new position. To prevent the plunger from moving back. insert the nut shown in Fig. 03. the nut must be cut on one of the flats, with the cut wide enough to fit over the plunger. • Remove the tensioning roller (5) after the plunger is locked in position. • Carefully lift off the timing belt if its to be used again. Mark its running direction with paint to refit it in the original position. Make sure that your hands are free from grease or oil. Any timing belt contaminated in this manner must be replaced. If the belt is to be re-used, store it where it cannot be kinked or contaminated. Take care not to disturb, the position of the injection pump sprocket. Two timing pins are normally required to reset the injection pump sprocket and the crankshaft pulley during the Installation of the timing belt. Fig. 04. shows the position of the timing sprockets and the tensioning rollers.
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Fig. 03. Details for the removal of the timing belt (refer to text).
Fig, 04. - View of the fitted timing belt the numbers are the same as in Fig.01.
•When fitting the timing belt, follow the instructions below. Make sure that the correct belt is fitted. The same applies to timing wheels:
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• Check that the timing marks "A" and "B" in Fig. 02 are still in the position shown. If this is not the case, rotate the crankshaft and camshaft accordingly, but remember that the pistons can hit the valves. Therefore turn both shafts very carefully, • Check the position of the injection pump sprocket. If this is still in the same Position, there is no need to reset it. If the engine has been turned, use the
Fig. 05. - Fitting the timing belt. The two timing pins slot. (Mot 910) are inserted as shown, Pins of similar diameter must be available to set the crankshaft and injector pump sprocket in the correct position.
two timing pins shown in Fig. 05 and insert one into the crankshaft pulley (provisionally fitted) and the other one into the pump sprocket. Turn the crankshaft pulley slowly until the mark "C" in the pulley (Fig. 06. and the timing mark "D" on the front oil seal carrier are in line. The timing rod can now be inserted.
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Fig. 06. Alignment of the crankshaft pulley mark (c) and the mark on the oil seal carrier, (D).
• Fit the timing belt over the sprockets. If the original belt is used, observe the running direction. • Fit the tensioning roller (5), place the washers in position and fit and tighten the nut. • Slacken the nut (3), securing the tensioning roller (2) in its outward position and allow the roller to push the timing belt towards the inside. Tighten the nut (3) In this position. • Remove the "slotted" nut from the Tensioning plunger. • Remove the two timing rods and turn the crankshaft two complete revolutions in its normal direction of rotation. • Re-check the 3 timing marks, i.e. the two marks on the camshaft sprocket must align and the two timing Pins must enter their location. If one of the set of marks Cannot be aligned, remove the timing belt and start again. • Slacken the nut (2) once more and allow the tensioning roller to push the belt towards the inside. Tighten the nut. The belt is now correctly tensioned. • The remaining operations are carried out in reverse order to the removal procedure.
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