Series Land Rover Gearbox - Fault Diagnosis

COLOUR KEY: Brown Rear drive output and transmission brake Yellow Transfer box Orange Main gearbox Red Front drive output shaft housing Grey Bell housing

Gearbox noisy
Insufficient oil or SAE 90EP oil not used; When in neutral - wear in primary pinion bearing, constant mesh gears or layshaft bearings; In all gears - worn speedometer gear, worn primary pinion or mainshaft bearings; All gears except 4th - constant gears or layshaft bearings worn; In one gear only - worn or damaged gear wheel. Transfer box - Insufficient oil or SAE 90EP oil not used; intermediate gear has excessive endfloat ( should be 0.1 - 0.2mm); worn bearings; excessive endfloat of output shaft.

Oil leaks
Over filling; loose or damaged drain/level plugs; joint washers wrongly fitted, damaged or missing; damaged or poorly fitted oil seals; cracked gearbox casing. Between gearbox and clutch - worn or damaged seal in clutch withdrawal unit. Between gearbox and transfer box - worn oil seal in gearbox.

Difficulty engaging gears
Forward gears - gear change mechanism incorrectly adjusted; clutch spinning or dragging; clutch plate sticking on pinion shaft. Reverse gear - selector stops incorrectly adjusted; bush loose in gear; reverse gear seized on shaft. Four wheel drive - locking pin seized in casing; broken selector shaft spring; selector shafts sticking.

Difficulty disengaging gears
Forward gears - faulty synchromesh; damaged mainshaft splines. Reverse gear - reverse gear seized on shaft. Four wheel drive - spring for selector shaft missing , broken or wrongly set; broken selector shaft spring; selector shafts sticking; front vs rear tyres incorrect or excessively worn.

Jumping out if gear
High range - transfer gear lever rubber boot not fitted correcty; weak or broken selector spring.
Low range - transfer gear lever rubber boot not fitted correcty; weak or broken selector spring; intermediate gear has excessive endfloat ( should be 0.1 - 0.2mm); incorrectly assembled transfer selector fork (fork should have threaded side of pinch bolt hole towards centre of the box).

Difficulty selecting first gear
If reverse sected easily then reverse stop is not adjusted correctly.