Q: How to remove and install a differential pinion seal on Chevrolet Avalanche,Silverado,Suburban,Tahoe,GMC Sierra,Yukon,Yukon Denali and Yukon XL?
A: To remove and install a differential pinion seal, first loosen the wheel lug nuts and raise the front or rear of the vehicle on jackstands. Remove the wheels and disconnect the driveshaft from the differential pinion flange. Rotate the pinion and record the torque required to rotate it. Mark the relationship of the pinion flange to the shaft and count the number of exposed threads on the shaft. Use a special tool or chain wrench to immobilize the flange and remove the pinion nut. Withdraw the flange and pry out the old seal. Install the new seal by lubricating the lips and tapping it evenly into position. Apply RTV sealant to the ends of the splines visible in the center of the flange and install the washer and a new pinion nut. Tighten the nut until the recorded number of threads are exposed and measure the torque required to rotate the pinion. Tighten the nut in small increments until it matches the recorded figure and exceeds it by 5 in-lbs. Reinstall all components and tighten all fasteners to their specified torque values.