318 rear main seal replacement
You can do the upper and lower with the motor in the car, heck I did the entire crank R&R in the car once! pull idler arm out and drop center link. drop pan, turn crank so the throws clear and then pull pan out front, it should clear pickup too. pull rear cap, use screw method or Lisle "sneaky pete" tool.
pull old one out and pull new one in. You can also remove flex plate bolts and main caps and you can pull rear of crank down about 1/8 inch to help install new one or remove old one. It wont move much but maybe just enough. Stagger rubber seals so it doesnt match cap mating surface, this helps seal it, and use plenty of oil in the installation. run all bolts into pan first then tighten in a criss/cross pattern to about 10 ft lbs, just snug. Its not that hard, all upper bearings can be 'rolled' out with crank and a heavy paper clip formed into a T and put into the crank oil hole. Itll will catch on bearing and push out when you turn crank. #3 Thrust bearing may not be doable with crank in block this way.
You can do the upper and lower with the motor in the car, heck I did the entire crank R&R in the car once! pull idler arm out and drop center link. drop pan, turn crank so the throws clear and then pull pan out front, it should clear pickup too. pull rear cap, use screw method or Lisle "sneaky pete" tool.
pull old one out and pull new one in. You can also remove flex plate bolts and main caps and you can pull rear of crank down about 1/8 inch to help install new one or remove old one. It wont move much but maybe just enough. Stagger rubber seals so it doesnt match cap mating surface, this helps seal it, and use plenty of oil in the installation. run all bolts into pan first then tighten in a criss/cross pattern to about 10 ft lbs, just snug. Its not that hard, all upper bearings can be 'rolled' out with crank and a heavy paper clip formed into a T and put into the crank oil hole. Itll will catch on bearing and push out when you turn crank. #3 Thrust bearing may not be doable with crank in block this way.