300Tdi Defender
41
TRANSFER GEARBOX
2
FAULT DIAGNOSIS
OIL LEAKS
Verify that oil leak is from transfer box and not main
gearbox before proceeding with checks.
Prior to road test
1. Check oil level in transfer box is correct.
2. Check tightness of level and drain plugs.
3. Check breather system for blockage. To validate
system pipe must be removed, inspected,
rectified as necessary and refitted.
4. Remove all traces of oil from exterior of transfer
box.
Take vehicle for short road test.
5. Identify source of leaks and rectify as follows.
Front or rear output seal leaking:-
1. Drain oil and remove leaking output flange.
2. Inspect seal track on flange for surface damage.
If damaged renew component.
3. Remove and discard oil seal.
4. Inspect seal locating bore and remove any sharp
edges which may damage new oil seal.
5. Fit new seal.
6. Fit output flange and all other parts.
7. Add oil to correct level into gearbox
See
SECTION 10, Maintenance, Under vehicle
maintenance .
Cover plate sealant leaking.
1. Drain oil and remove leaking cover plate.
2. Remove all traces of joint sealant from both joint
faces.
3. Degrease all components and apply a thin film of
Hylomar sealant, to both joint faces.
4. Apply thread sealant to bolts which come into
contact with gearbox oil.
5. Refit cover plate.
CAUTION: Care must be taken not to
overtighten fixings.
Leak between main and transfer gearboxes.
1. Site vehicle onto a ramp .
2. Select neutral in transfer box and select 4th gear
in main gearbox.
3. Run engine at 2000 rpm with clutch/drive
engaged.
4. Observe joint between main and transfer boxes.
5. If oil leak is found establish if it is gear oil.
6. If so, leak is originating from transfer box.
7. Check two inner (main/transfer) bolts are oil
tight, as these holes are tapped into main
transfer case.
8. Remove transfer box to inspect mainshaft collar
seal track condition, and front face of transfer
case for porosity
See Repair, Transfer
gearbox .
9. If these areas require servicing, transfer gearbox
input seal must also be renewed.
CAUTION: Avoid damaging new seal lip
and ensure seal is fitted flush with
machined face. Also ensure new seal is
not damaged when refitting transfer gearbox.
10. If red ATF type oil is seen leaking during
workshop test, investigate main gearbox for
cause of leak.
Detent plug or electrical switch leaks.
1. Detent plugs and electrical switches do not
usually leak. It must be noted that they fit into
open tapped holes in transfer case and therefore
should be considered when looking for source of
leak.