Genuine Mercury Grand Marquis Differential Seal

Mercury Grand Marquis Differential Seal Parts Questions & Experts Answers

• Oil Seal Assembly
  F89Z-4676-AA
  Q: How to remove and replace the rear differential seal on a Mercury Grand Marquis?

  A:

  Raise the rear of the vehicle and place it securely on jackstands. Remove the rear wheels and brake drums. Mark the driveshaft and companion flange for ease of realignment during reassembly, then remove the driveshaft. Mark the relationship between the pinion and companion flange. Using an inch-pound torque wrench, measure and record the torque required to turn the pinion nut through several revolutions (pinion bearing preload). Using a suitable tool, hold the companion flange and remove the pinion nut. Using a suitable puller, remove the companion flange. Pry out the old seal with a slide hammer and reversed jaws or other appropriate tool. It may also be removed with a hammer and chisel. Clean the oil seal mounting surface. Tap the new seal into place, taking care to insert it squarely. Inspect the splines on the pinion shaft for burrs and nicks. Remove any rough areas with a crocus cloth. Wipe the splines clean. Install the companion flange, aligning it with the marks made during removal. Gently tap the flange on with a soft-faced hammer until you can start the pinion nut on the pinion shaft. Using a suitable tool, hold the companion flange while tightening the pinion nut to the minimum torque. While tightening, take frequent rotational torque measurements, using the inch-pound torque wrench, until the measurement recorded is reached. Caution: If the measurement recorded was less than the pinion bearing preload torque, continue tightening until the specified torque is reached. If it was more than specified, stop when the specified torque is reached. Under no circumstances should the pinion nut be backed off to reduce pinion bearing preload. Increase the nut torque in small increments and check the preload after each increase. Reinstall the driveshaft, brake drums and wheels. Check the differential oil level and fill as necessary. Lower the vehicle and take a test drive to check for leaks.