1996 GMC Forward Control 4.3 Z, AutomaticFACTORY OEM SERVICE PROCEDURE

Oil Pump Assembly

  1. Turbine shaft seals should be installed prior to oil pump installation. Position Seal Installer (J-36418-1 ) on input shaft. See Fig 1. Adjustment screw in seal installer must be adjusted to obtain correct height for each seal installation. Install 4 turbine shaft seals.
    Fig 1: Installing & Sizing Turbine Shaft Seals
    G92A13631Courtesy of GENERAL MOTORS CORP.
  2. Turbine shaft seals must be sized using Seal Sizer (J-36418-2A ) after installation. Install aligning pins in 2 opposing pump bolt holes in case. Ensure thrust washer is installed on rear of oil pump. Thrust washer can be retained using petroleum jelly.
  3. Install oil pump into case, aligning filter and pressure regulator holes with holes in case. Install retaining bolts. Tighten bolts to specification. See TORQUE SPECIFICATIONS . Place transmission in a horizontal position.
  4. Turbine shaft should rotate by hand. If turbine shaft will not rotate, loosen pump retaining bolts and attempt to rotate shaft again. If shaft now turns, reverse and input assemblies have not been indexed properly or some other assembly problem has occurred, such as thrust washer not positioned properly.
  5. Check transmission end play. See TRANSMISSION END PLAY CHECK  under TRANSMISSION DISASSEMBLY. Transmission end play should be .005-.036" (.13-.91 mm). If transmission end play is not within specification, thrust washer must be changed between oil pump and input housing.
  6. See OIL PUMP THRUST WASHER SPECIFICATIONS . Install thrust washer, and recheck end play. Install torque converter. Ensure converter hub is aligned with oil pump. Install torque converter retaining strap to hold converter.
OIL PUMP THRUST WASHER SPECIFICATIONS

ID Number Thickness In. (mm)
67 .074-.078 (1.88-1.98)
68 .080-.084 (2.03-2.13)
69 .087-.091 (2.21-2.31)
70 .094-.098 (2.39-2.49)
71 .100-.104 (2.54-2.64)
72 .107-.111 (2.72-2.82)
73 .113-.118 (2.87-3.00)
74 .120-.124 (3.05-3.15)
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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