Jaguar X-Type Sedan and Estate (Wagon). Manual - part 22
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1
Road Conditions
An experienced technician will always establish a route that will be used for all NVH diagnosis road tests. The road selected should be
reasonably smooth, level and free of undulations (unless a particular condition needs to be identified). A smooth asphalt road that allows
driving over a range of speeds is best. Gravel or bumpy roads are unsuitable because of the additional road noise produced. Once the route
is established and consistently used, the road noise variable is eliminated from the test results.
• NOTE: Some concerns may be apparent only on smooth asphalt roads.
If a customer complains of a noise or vibration on a particular road and only on a particular road, the source of the concern may be the road
surface. If possible, try to test the vehicle on the same type of road.
Vehicle Preparation
Carry out a thorough visual inspection of the vehicle before carrying out the road test. Note anything which is unusual. Do not repair or
adjust any condition until the road test is carried out, unless the vehicle is inoperative or the condition could pose a hazard to the
technician.
After verifying the condition has been corrected, make sure all components removed have been installed.
Lift Test
After a road test, it is sometimes useful to do a similar test on a lift.
When carrying out the high-speed shake diagnosis or engine accessory vibration diagnosis on a lift, observe the following precautions:
WARNING: If only one drive wheel is allowed to rotate, speed must be limited to 55 km/h (35 mph) indicated on the speedometer
since actual wheel speed will be twice that indicated on the speedometer. Speed exceeding 55 km/h (35 mph) or allowing the drive wheel to
hang unsupported could result in tire disintegration, differential failure, constant velocity joint and driveshaft failure, which could cause
serious personal injury and extensive vehicle damage. Failure to follow these instructions may result in personal injury.
CAUTION: The suspension should not be allowed to hang free. W hen the CV joint is run at a very high angle, extra vibration as well as
damage to the seals and joints can occur.
The suspension lower arms should be supported as far outboard as possible. To bring the vehicle to its correct ride height, the full weight of
the vehicle should be supported in the rear by floor jacks. For additional information, refer to
REFER to:
Jacking
(100-02 Jacking and Lifting, Description and Operation).
1. Raise and support the vehicle. For additional information, refer to
REFER to:
Lifting
(100-02 Jacking and Lifting, Description and Operation).
1.
2. Explore the speed range of interest using the Road Test Quick Checks as previously described.
2.
3. Carry out a coast down in neutral. If the vehicle is free of vibration when operating at a steady indicated speed and behaves very
differently in drive and coast, a transmission concern is likely.
3.
Note, however, that a test on the lift may produce different vibrations and noises than a road test because of the effect of the lift. It is not
unusual to find vibrations on the lift that were not found in the road test. If the condition found on the road can be duplicated on the lift,
carrying out experiments on the lift may save a great deal of time.
Symptom Chart
Symptom
Possible Sources
Action
High-speed shake
Wheel end vibration
Engine/gearbox/transfer box
Driveline
GO to Pinpoint Test A.
Tip-in moan
Air cleaner
Power steering (PS)
Powertrain
Engine mounts
Exhaust system
GO to Pointpoint Test B.
Idle boom/shake/vibration, or shudder
Cable(s)/hoses(s)
Engine mounts
Exhaust system
Belt/pulleys
GO to Pinpoint Test C.
W heel end vibration analysis
Suspension/front or rear wheel drive half shaft and joints
Tires/wheels
Wheel bearings
Front or rear wheel drive half shaft joint boots
GO to Pinpoint Test D.
Non-axle noise
Trim/mouldings
A/C system
Accessories
GO to Pinpoint Test E.
Pinpoint Tests
• NOTE: These Pinpoint Tests are designed to take the technician through a step-by-step diagnosis procedure to determine the cause of a
condition. It may not always be necessary to follow the chart to its conclusion. Carry out only the Pinpoint Test steps necessary to correct
the condition. Then check operation of the system to make sure the condition is corrected.
After verifying that the condition has been corrected, make sure all components removed have been installed.
PINPOINT TEST A : HIGH-SPEED SHAKE
TEST CONDITIONS
DETAILS/RESULTS/ACTIONS
A1: NEUTRAL COAST
Carry out the neutral coast test.