Buick Encore: Diagnostic information and procedures

SPECIFICATIONS

FASTENER TIGHTENING SPECIFICATIONS

Fastener Tightening Specifications

ADHESIVES, FLUIDS, LUBRICANTS, AND SEALERS

Adhesives, Fluids, Lubricants, and Sealers

DIAGNOSTIC INFORMATION AND PROCEDURES

TIRE DIAGNOSIS - IRREGULAR OR PREMATURE WEAR

Tire Wear

Fig. 1: Identifying Types Of Tire Wear

Inspection Procedure

1. Inspect the front tire wear.
2. Inspect the rear tire wear.
3. Rotate the tires if any of the following conditions exist:

• The amount of time or mileage since the last tire rotation matches the maintenance schedule.
• The outer tread blocks are worn more than the middle tread blocks (1).
• The outer tread blocks are worn more than the inner tread blocks (2).
• The middle tread blocks are worn more than the outer tread blocks (4).

4. Measure the wheel alignment if any of the following conditions exist:

• The tread blocks have feathered edges (3).
• The outer tread blocks are worn more than the inner tread blocks (2).
• The inner tread blocks are worn more than the outer tread blocks (2)

5. Inspect the struts or the shock absorbers if the tire tread exhibits a cupped appearance (3).

TIRE DIAGNOSIS - WADDLE COMPLAINT

Fig. 2: Identifying Tire Wobble/Waddle

Tire waddle is a side to side movement at the front of the vehicle and/or the rear of the vehicle. Tire waddle can be caused by the following conditions:

• A steel belt not being straight within the tire
• Excessive lateral runout of the tire
• Excessive lateral runout of the wheel

The tire waddle is most noticeable at a low speed of about 8-48 km/h (5-30 mph). Tire waddle may appear as ride roughness at 80-113 km/h (50-70 mph). Tire waddle may appear as a vibration at 80-113 km/h (50-70 mph).

Inspection Procedure

1. Raise and support the vehicle with safety stands. Refer to Lifting and Jacking the Vehicle .

WARNING: Wear gloves when inspecting the tires in order to prevent personal injury from steel belts sticking through the tire.

2. Perform the following preliminary inspection:

1. Mark the tire with a crayon in order to note the start and the stop position.
2. Rotate each tire and wheel by hand.
3. Inspect the tire for bulges or bent wheels. Replace as necessary.

3. Use tire substitution in order to identify the faulty tire. Perform the following steps for a tire substitution check:

1. Use a comparable tire in order to replace each tire, one at a time.
2. Test drive the vehicle.
3. If the problem is tire or wheel related, you will eliminate the problem when you remove the faulty tire from the vehicle.

Wheel mounting surface check

Replace any wheels that are bent or dented, or have excessive lateral or radial runout. Wheels with runout greater than specified may cause objectionable vibrations.

Fig. 3: Checking Wheel Mounting Surface

1. Use a straight edge 203-229 mm (8-9 in) long. Place the straight edge on the wheel inboard mounting surface. Try to rock the straightedge up and down within the mounting surface.

Fig. 4: Inspecting Wheel Inboard Mounting Surface

2. Repeat this procedure on at least 3-4 different positions on the inboard mounting surface.

• The outer ring of the mounting surface normally is raised above everything inside the mounting surface.
• The mounting surface will be raised above the outer ring if the wheel mounting surface has been bent on a tire changer.
• If you can rock the straight edge, the mounting surface is bent and you must replace the wheel.

Fig. 5: Inspecting Mounting Wheel/Nut Holes For Damage Caused From Over-Torquing The Wheel/Nuts

3. Inspect the mounting wheel/nut holes for damage caused from over-torquing the wheel/nuts. Inspect for collapsed wheel/nut bosses. Inspect for cracked wheel bosses.

CAUTION: The use of non-GM original equipment wheels may cause:

• Damage to the wheel bearing, the wheel fasteners and the wheel
• Tire damage caused by the modified clearance to the adjacent vehicle components
• Adverse vehicle steering stability caused by the modified scrub radius
• Damage to the vehicle caused by the modified ground clearance
• Speedometer and odometer inaccuracy

NOTE:

Replacement wheels must be equivalent to the original equipment wheels in the following ways:

• The load capacity
• The wheel diameter
• The rim width
• The wheel offset
• The mounting configuration

A wheel of the incorrect size or type may affect the following conditions:

• Wheel and hub-bearing life
• Brake cooling
• Speedometer/odometer calibration
• Vehicle ground clearance
• Tire clearance to the body and the chassis

4. Replace the wheel if the wheel is bent.
5. Replace the wheel if the wheel/nut boss area is cracked.

Identify steel wheels with a 2 or 3-letter code stamped into the rim near the valve stem. Aluminum wheels have the code, the part number, and the manufacturer identification cast into the back side of the wheel.

Radial tire lead/pull correction

Lead/pull is the deviation of the vehicle from a straight path on a level road with no pressure on the steering wheel. Lead is usually caused by:

• Incorrect alignment
• Uneven brake adjustment
• Tire construction

The way in which a tire is built can produce lead/pull in the vehicle. Off-center belts on radial tires can cause the tire to develop a side force while the vehicle rolls straight down the road. If one side of the tire has even a little larger diameter than the diameter of the other side, the tire will tend to roll to one side. Unequal diameters will cause the tire to develop a side force which can produce vehicle lead/pull.

The radial lead/pull diagnosis chart should be used to determine whether the problem originates from an alignment problem or from the tires. Part of the lead diagnosis procedure calls for tire rotation that is different from the proper tire rotation pattern. If a medium-mileage to high-mileage tire is moved to the other side of the vehicle, be sure to check for ride roughness. Rear tires will not cause lead/pull.

Radial Tire Lead/Pull Correction

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