4R100 Automatic Transmission Oil Pump RF-F81P-7B324-AA

Typical Faults:

1. Rotor/Gear Wear

   • Symptom: Low line pressure (P0841/P0868 codes, delayed shifts)

   • Cause: Contaminated ATF or metal debris scoring surfaces

2. Seal Failure

   • Symptom: Pressure loss at idle (pump whine)

   • Trigger: Hardened/rolled seals from heat/age

3. Cavitation Damage

   • Symptom: Foamy ATF, erratic shifts

   • Root Cause: Clogged filter or aerated fluid

Critical Checks:

• Clearance: Rotor-to-housing >0.15mm = replace

• Prime Test: Should generate 20+ psi instantly at crank

• Debris Inspection: Metal flakes indicate imminent failure

Pro Tip: Always replace pump and torque converter simultaneously – 70% of pump failures originate from TC debris.