Manual transmission — fault diagnosis (Opel Ascona C)

Symptom/ Cause(s)

Synchronizers work poorly or inefficiently/

• The synchronizer cone rings are worn, cracked or damaged
• Synchronizers are worn or damaged.

Knocks out the transmission/

• The gear shift mechanism is worn out
• The synchronizers are badly worn out
• The gear shift fork is worn out.

The box is making noise/

• The oil in the gearbox is incorrectly selected or the oil level is too low
• The gear teeth are badly worn or damaged
• The intermediate thrust washers of the gears are worn out, which results in excessive axial play
• The bearings are worn out.

Problems with gear shifting/

• The clutch pedal is not adjusted correctly.

Noise when cornering/

• Defective wheel bearings or drive shafts
• Differential failure.

Note: Be very careful not to disassemble the box for reasons that are no more than minor inconveniences. "Noisy" gearboxes or gearboxes whose synchronizers fail during rapid gear shifting can still serve in this condition for quite a long time. To eliminate noise, a worn-out gearbox usually has to be completely disassembled, since when installing old and new parts together, the noise will still not disappear. Therefore, the decision to overhaul the box should be made with great caution.