300Tdi Discovery
R380
1
FAULT DIAGNOSIS
MANUAL GEARBOX
Symptom - Gear jumps out of engagement (any
forward gear)
1. Check condition and security of transmission
and engine mountings.
2. Check in situ, gear lever and selector
adjustments.
3. In situ, remove gearshift and check selector rail
yoke security.
Also check selector detent spring tension and
both spool retainers.
Suspect internal fault
See remove and overhaul procedure.
4. Check action/operation of main selector rail and
forks.
5. Check condition of synchromesh and gear dog
teeth.
6. Check main and layshaft end floats bearings and
adjustments.
7. Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Reverse gear only jumps out of
engagment
1. Check condition and security of transmission
and engine mountings.
2. Check in situ, gear lever and selector
adjustments.
3. In situ, remove gearshift and check selector rail
yoke security.
Also check selector detent spring tension and
both spool retainers.
Suspect internal fault
See remove and overhaul procedure.
4. Check action/operation of main selector rail and
reverse lever.
5. Check condition of reverse gear, angled
bearings and shaft.
6. Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Excessive force required to engage or
change gear, vehicle stationary or moving.
1. Check lubricant specification and level, if low do
not top up at this stage.
2. In situ, lubricate gear mechanism, and check
selector adjustments.
3. In situ, remove gearshift and check selector rail
is free and that the yoke is secure. Also check
selector detent spring tension and both spool
retainers.
4. Drain lubricant and check for contamination or
metal particles.
Suspect worn synchromesh unit or baulk rings
on affected gears. See remove and overhaul
procedure.
Symptom - Noisy gear engagement, vehicle
stationary.
See CLUTCH, Fault diagnosis, Clutch
Noise - Mechanical Faults
Symptom - Noisy gear selection, vehicle moving.
1. Confirm that clutch operation is satisfactory.
2. Establish which gear/gears is causing noise.
3. Check lubricant specification and level, if low do
not top up at this stage.
4. Drain lubricant and check for contamination or
metal particles.
Suspect worn synchromesh. See remove and
overhaul procedure.
5. Check condition of synchromesh unit, springs
and cones for distortion and wear. Also check
dog teeth for damage and cone mating surface
on gear for signs of overheating.
6. Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Noise from gearbox in neutral, which
changes tone or becomes worse when clutch is
depressed.
See CLUTCH, Fault diagnosis, Clutch
Noise - Mechanical Faults
