Ford 2003 Mustang Workshop Manual page 111

4. While the noise is occurring, either place an EngineEAR probe near the IAC valve and the inlet
tube, or create a 6.35 mm (0.25 in)-12.7 mm (0.50 in) air gap between the inlet tube and the
clean air tube. If the IAC valve is making the noise, install a new IAC valve.
5. Test the vehicle for normal operation.
Steering Gear Grunt/Shudder Test
1. Start and run the vehicle to operating temperature.
2. Set engine idle speed to 1200 rpm.
3. CAUTION: Do not hold the steering wheel against the stops for more than three to
five seconds at a time. Damage to the power steering pump will occur.
Rotate the steering wheel to the RH stop, then turn the steering wheel 90° back from that
position. Turn the steering wheel slowly in a 15° to 30° arc.
4. Turn the steering wheel another 90°. Turn the steering wheel slowly in a 15° to 30° arc.
5. Repeat the test with power steering fluid at different temperatures.
6. If a light grunt is heard or a low (50-200 Hz) shudder is present, this is a normal steering system
condition.
7. If a loud grunt is heard, or a strong shudder is felt, fill and purge the power steering system.
Checking Tooth Contact Pattern and Condition of the Ring and Pinion
There are two basic types of conditions that will produce ring and pinion noise. The first type is a howl
or chuckle produced by broken, cracked, chipped, scored or forcibly damaged gear teeth and is
usually quite audible over the entire speed range. The second type of ring and pinion noise pertains to
the mesh pattern of the gear pattern. This gear noise can be recognized as it produces a cycling pitch
or whine. Ring and pinion noise tends to peak in a narrow speed range or ranges, and will tend to
remain constant in pitch.
1. Raise and support the vehicle. For additional information, refer to
2. Drain the axle lubricant. Refer to
Ford 8.8 integral axles.
3. Remove the carrier assembly or the axle housing cover depending on the axle type. Refer to
Section 205-02A
4. Inspect the gear set for scoring or damage.
Section 205-02A
for Ford 7.5 rear axles or
for Ford 7.5 rear axles or
Section 205-02B for Ford 8.8 integral axles.
Section 100-02 .
Section 205-02B for