F 550 2WD Super Duty V10-6.8L VIN Z Bi-Fuel (2001)
4. Inspect the internal ball-track grooves of the rack piston for brinelling (dents) or spalling (flaking).
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If either condition exists, install a new rack piston, input shaft, worm valve assembly and the set of balls as an assembly.
5. Inspect the input shaft, worm valve assembly, ball track grooves, thrust bearing, and the ball bearing areas.
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Check for brinelling (dents) or spalling (flaking).
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Inspect the sealing areas of the input shaft and valve for nicks.
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Run a fingernail edge across the sealing surfaces to detect steps.
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Inspect for discoloration from excess heat.
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If any of these conditions exist, install a new input shaft, valve housing, valve worm assembly and the set of balls as an assembly.
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Also install a new rack piston if brinelling or spalling is found.
6. NOTE: In carrying out the internal leakage test after assembling the gear, make sure internal leakage over 3.8 liters/min (1.0 gpm) is not caused
by the incorrect installation of seals on the worm shaft, rack piston and valve assembly.
NOTE: Install a new housing only if internal leakage is greater than 3.8 liters/min (1.0 gpm).
Make sure a seal is not causing the leak.
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The bore of the housing may show signs of scoring but these signs may indicate normal wear.
7. Inspect the face of the housing for nicks that would prevent correct sealing. Install a new housing if the nicks cannot be easily removed with a
fine-tooth flat file without damage to the housing.
8. For TAS4O, inspect the side cover DU bushing for damage and check the side cover bushing-to-sector shaft clearance.
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If damage exists, or if clearance exceeds 0.20 mm (0.008 inch), then install a new side cover/bushing assembly.
