16 · Diagnostics

S23 Gearbox noise in a specific gear

Fault diagnosisS23 Gearbox noise in a specific gear

With the engine running, a noise is heard (whilsting inside the gearbox) when a specific gear is engaged

This noise decreases or disappears on changing gear.

Step	Test procedure	Result	Action
1	CHECK SYNCHRONIZER RINGS Overhaul the gearbox (see OVERHAULING GEARBOX Assembly 2110B). In particular, check the synchronizer rings for the gear involved: they should not show signs of wear on the inner surfaces	OK	Move onto step 2
1		Seals worn	Replace the synchronizers End of diagnosis
2	CHECK GEARS Overhaul the gearbox (see OVERHAULING GEARBOX Assembly 2110B). In particular, check the teeth of the gear concerned: they should not be worn or show signs of seizing	OK	Move onto step 3
2		Gears worn	Replace the gears involved End of diagnosis
3	REDUCTION TORQUE CHECK Check the crown wheel and pinion reduction gear (see OVERHAULING GEARBOX Assembly 2110D) In particular: it should not be worn or damaged there should not be excessive clearance	OK	Move onto step 4
3		Reduction gear damaged	Restore the clearance or, if necessary, replace the reduction gear End of diagnosis
4	CHECK CORRECT OPERATION Check that the fault is no longer present	OK	End of diagnosis
4		Fault persists	Incorrect selection of diagnostic procedure

Parts & tools for this job For 1997 Alfa Romeo 156

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