[mustangII460]

Replacing the Rear Main Seal
If your car has the rope type seal, replace it with the newer neoprene seal. Note that if the car had a rope type seal in it before, it will have a small pin (like a nail) sticking into the seal cavity in the main cap. It must be driven or ground out before the new seal can be installed. Seals really aren't that hard to install, especially on a 289 Mustang. Unbolt the idler arm and push steering linkage away. Remove the starter. Drain and unbolt pan and remove it. Loosen all the main cap bolts a couple of turns. Remove rear cap. The old seal will usually slide around so you can grab it and pull it out if you rotate the crank by hand in the direction you pull the seal. If it won't come, there are inexpensive tools that thread into the old seal to pull it out. BE CAREFUL NOT TO NICK THE CRANK. Install the new seal by carefully pushing it in place while rotating the crank in the same direction as the push. Lube the seal with oil and go easy as the sharp edges of the block will try to shave off pieces of the seal. Leave one end sticking out of the block 3/8" and match the one in the cap to it. Lube the lower seal and install the cap with a small bit of RTV near the rear of the parting surface of the cap. Torque all the mains and reinstall the pan. Don't use a gasket, just RTV Ultra Black, thick where the end seals went and thin on the flange. Everything must be cleaned with lacquer thinner first to get a good bond. Torque the pan tight to the block while the RTV is wet and it will never leak again.