Land Rover Defender: Driveline System

DIAGNOSIS AND TESTING

PRINCIPLE OF OPERATION

For a detailed description of the driveline system and operation, refer to the relevant description and operation section in the workshop manual.

INSPECTION AND VERIFICATION

CAUTION: Diagnosis by substitution from a donor vehicle is NOT acceptable. Substitution of control modules does not guarantee confirmation of a fault, and may also cause additional faults in the vehicle being tested and/or the donor vehicle

NOTE: Check and rectify basic faults before beginning diagnostic routines involving pinpoint tests

1. Verify the customer concern
   • If a road test is necessary make sure the vehicle is safe to do so
2. Visually inspect for obvious signs of mechanical damage

Visual Inspection

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step
4. If the cause is not visually evident, verify the symptom and refer to the symptom chart, alternatively check for diagnostic trouble codes (DTCs) and refer to the DTC index

DIAGNOSTICS FOR DRIVELINE NOISE AND VIBRATION

NOTE: If vibration is felt through the steering wheel, then the diagnostics detailed below are not applicable. Vibration felt through the steering should be investigated and rectified separately.

In the case of noise and/or vibration from the driveline system, follow the remedial steps set out below:

1. Check for Metallic Debris Within The Differential Units: Remove the differential (front and rear) drain plugs and check for evidence of metallic debris. While it is normal to see smooth graphite or fine grained deposits (see left-side and centre illustrations below), if there is evidence of sharp spikes or shards of metallic debris on the drain plug (see right-side illustration below), then this indicates an internal failure of the differential unit. If there is evidence of sharp spikes or shards of metallic debris on the drain plug, then replace the drain plug as found and replace the differential unit as required. If there is no evidence of metallic debris on the drain plug, discard the old plug, fit a new drain plug and proceed to the next step.

2. In the case of either noise and/or vibration, loosen off all differential and associated propshaft fixings. Resettle the differential units and then re-tighten the fixings in a diagonal pattern for both differential units and the associated propshafts. Once all the fixings are secured to the correct torque, road test the vehicle and check for any indications of driveline noise or vibration. If noise and/or vibration is still evident, proceed to the next step.
3. Note the position of the front driveshaft prior to removal. Remove the driveshaft. Once removed, check the axle tube needle roller bearings for signs of damage. If the needle roller bearings are damaged, as indicated by a flattening of the surface of the roller bearings (see illustration below), then both the driveshaft and axle tube should be replaced. If the needle roller bearings are undamaged, the driveshaft should be rotated by 180 degrees (relative to its original installation) and re-fitted. Road test the vehicle and check for any indications of driveline noise or vibration.

IDENTIFY THE CONDITION

GEAR HOWL AND WHINE

Howling or whining of the ring gear and pinion is due to an incorrect gear pattern, gear damage or incorrect bearing preload

BEARING WHINE

Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by worn/damaged pinion bearings, which are operating at driveshaft speed. Bearing noise occurs at all driving speeds. This distinguishes it from gear whine which is speed dependent

As noted, pinion bearings make a high-pitched, whistling noise, usually at all speeds. If however there is only one pinion bearing that is worn/damaged, the noise may vary in different driving phases A wheel bearing noise can be mistaken for a pinion bearing noise

CHUCKLE

Chuckle that occurs on the coast driving phase is usually caused by excessive clearance between the differential gear hub and the differential case bore Damage to a gear tooth on the coast side can cause a noise identical to a chuckle. A very small tooth nick or ridge on the edge of a tooth can cause the noise

KNOCK

Knock, which can occur on all driving phases, has several causes including damaged teeth or gearset

A gear tooth damaged on the drive side is a common cause of the knock

CLUNK

Clunk is a metallic noise heard when the automatic transmission is engaged in REVERSE or DRIVE. The noise may also occur when the throttle is applied or released. Clunk is caused by transmission calibration, backlash in the driveline or loose suspension components and is felt or heard in the vicinity of the rear drive axle

BEARING RUMBLE

Bearing rumble sounds like marbles being tumbled. This condition is usually caused by a worn/damaged wheel bearing. The lower pitch is because the wheel bearing turns at only about one-third of the driveshaft speed. Wheel bearing noise also may be high-pitched, similar to gear noise, but will be evident in all four driving modes

SYMPTOM CHART

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