Jaguar XJ (X350). Manual — part 726

Diagnosis and testing

Accessory Drive - 3.0L/3.5L/4.2L

No data

Accessory Drive - 2.7L Diesel

Principles of Operation

The 2.7L diesel engine uses two accessory drive systems, the front end accessory drive (FEAD), and

the fuel injection pump drive.

FEAD

The FEAD drives: the coolant pump, the generator, the power assisted steering pump, and the air

conditioning compressor, driven from the crankshaft pulley via a single six-ribbed belt.

Fuel injection pump drive

The fuel injection pump is driven from the exhaust camshaft of the left-hand cylinder bank, by a

single, toothed belt.

The fuel injection pump is NOT timed to the engine.

Inspection and Verification

1 . Verify the customer concern.

2 . Visually inspect for obvious mechanical faults.

FEAD

Fuel injection pump belt

Belt condition

(cracking/damage/contamination)

Belt tension

Function of driven components (siezed, etc)

Pulley alignment

Security/correct fitment of cover

Check for debris inside the cover

Belt condition

(cracking/damage/contamination)

Belt tension

3 . If an obvious cause for an observed or reported concern is found, correct the cause (if possible)

before proceeding to the next step.

Noise definitions

Description of

noise

Definition/Possible cause

Squeal

Continuous shriek, most noticeable when the engine is accelerated (usually

associated with lack of belt tension, contamination or wet slip)

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Chirp

Twittering noise that usually stops at engine speeds above idle. Usually associated

with misaligned pulleys

Whine

Continuous noise, changing frequency with engine speed, generally associated with

rotating components (generator, idler, etc)

Rattle

Metallic knocking, often a loose component or tensioner fault

Rumble

Bearing noise

Symptoms (FEAD)

Symptom

Possible cause

Action

Noise (see

definitions above)

Belt condition

Belt tension

Pulleys

misaligned

Driven

component
s

Check the belt condition (see visual inspection). Check the

tensioner function. GO to Pinpoint Test G552803p1.

Check the pulley alignment. Check the driven components

for excessive resistance to rotation. Rectify as necessary.

Drive belt does not

hold tension

Belt condition

Tensioner fault

Check the belt condition (see visual inspection). Check the

tensioner function. Rectify as necessary.

Symptoms (Fuel injection pump belt)

Symptom

Possible cause

Action

Noise (see

definitions above)

Belt condition

Belt fouling cover

Tensioner

bearing
failure

Fuel injection

pump failure

Check the belt condition (see visual inspection). Check the

belt cover for indications of fouling (this may indicate a

pump misalignment),

Fuel Injection Pump The belt tensioner must be renewed

if the belt is removed, making a check of the bearing

impractical. Remove the belt, check the fuel injection

pump pulley for security. Check the fuel injection pump for

excessive resistance to rotation (excessive resistance in

the pump will cause the pulley securing nut to loosen as a

design feature). Check for diagnostic trouble codes (DTCs)

indicating a pump malfunction,

Fuel Charging and Controls

Loss of drive (with

no drive to the

fuel injection

pump, the engine

will not run)

Belt

broken/strip
ped teeth

Drive pulleys

loose

Investigate the cause of the belt breakage/damage (a belt

broken at a 45 degree angle normally indicates a shear, a

break straight across the belt normally indicates that the

belt has been crimped). Check the fuel injection pump for

excessive resistance to rotation (excessive resistance in

the pump will cause the pulley securing nut to loosen as a

design feature). Check for DTCs indicating a pump

malfunction,

Fuel Charging and Controls

Pinpoint tests

PINPOINT TEST G552803p1 :
ELIMINATE THE FEAD AS THE
SOURCE OF NOISE

G552803t1 : CHECK FOR THE PRESENCE OF NOISE WITH THE FEAD BELT
DISCONNECTED

1. Remove the ignition key. 2. Disconnect the FEAD belt,

Accessory Drive Belt - 2.7L Diesel (12.10.40) 3. Start the engine and allow to idle. 4. Check for the

presence of the noise.

Is the noise still apparent?

-> Yes

The FEAD is not the cause of the noise. Confirm the symptoms, check for alternative causes.

-> No

Inspect the FEAD belt and driven components. Check the driven components for excessive resistance

to rotation.

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