1. check the back of the intake and heads to be sure that any leak on the bottom of the engine is not actually coming from there and not the rear seal.
2. remove
oil pan - all bolts. when removing pan, i use a wide flat screwdriver which i gently hit into the gasket all around. this slowly wedges the pan off. you should not lever with the screwdriver so you dont mess up the sealing surface.
3. can be done with the engine in the car. original style frames will have a crossmember just below but in front of the rear main cap
4. remove the rear main cap bolts. need to pull the cap loose. it is a tight fit and this is not easy, especially in the car. I used long threaded rods into the
oil pan bolt holes and pulled it down and also back and forth. you could use a sliding hammer if not under the car (no room if under the car on jackstands) i put a metal plate across the 2 long threaded rods and levered that plate against the frame crossmember and even the block plate with a long bar. getting the cap off is hard to do. it took me several hours over a couple of days. just keep working it
5. the bottom half of the rear main comes off easily, usually with the cap. the top of the rear seal may be able to be just pushed out around the crank. if it has been in there a long time, might be difficult. there are special curved tools that can help. do NOT scratch the crankshaft in any way.
6. install the new top half of the rear seal. make sure the ends of the seal are clocked slightly so the seam between the top and bottom of the seal is not aligned with the seam of the main cap - the rear seal should be slightly off to decrease the chance for a leak. i put a tiny drop of silicone sealer on the ends of the seal but most don't. i think i put the bottom half of the seal in the cap and then installed the rear cap.
7. reinstall the cap. i used a bit of silicone sealer on the top ends of the cap. getting the sides to seal is a bit of an art - whether using the rubber seals and nails or just a thick bead of silicone or The Right Stuff sealer. there are a few vdeos on youtube that show this. torque the bolts correctly. i was told not to use the rubber side seals at all, but i think if I had to do it again, i might just really coat them in silicone and slide them in, then the nails.
8. i also put some sealer on the inside seams of the cap, deep inside the block behind the crankshaft, but I dont think these are helpful
9. clean off the
oil pan surfaces and install with new gasket. i like to put a bit of sealer where the seams are on the front and back (the seams of the rear cap and I think there are similar seams in front)