The engine's rear main seal prevents oil from leaking around the rear of the crankshaft. There are two types of rear main seals, one-piece seals and two-piece seals. The two-piece seal is easier to replace because it is not necessary to remove the transmission, clutch and flywheel (stick shift), or the transmission and flex plate (automatic). Replacement of the two-piece rear main seal can be accomplished with the engine in the vehicle.
Park the vehicle on level ground and set the parking brake. Raise the front of the vehicle with a jack and support it on jack stands.
Place a drain pan under the oil pan drain plug. Remove the oil pan drain plug with a ratchet and socket. Wait for all the oil to drain.
Unbolt the oil pan bolts. Tap the oil pan with a rubber mallet to break it loose from the engine block. You may have to stick a screwdriver in between the oil pan and engine block in several places to gently pry it loose from the block.
Remove the old oil pan gasket. Remove any stuck-on gasket material from the pan and block with a putty knife. Wipe the pan and block clean with a shop rag.
Remove the rear main bearing cap. Loosen all the other main bearing caps just enough to let the crankshaft drop down about 1/16 of an inch.
Tap out the bottom half of the rear main seal with a hammer and a small brass punch until you have enough of the seal exposed to grab it with a pair of pliers.
Tap out the top half of the rear main seal from the engine block with the hammer and small brass punch until you have enough of the seal exposed to grab it with needle-nose pliers. Note the direction that the lip of the rear main seal halves face. The lip faces the front of the engine. Be careful not to nick or scratch any metal surfaces on the rear main bearing cap, engine block or crankshaft. Clean the mating surfaces of the engine block and rear main bearing cap with a shop rag dampened with parts cleaning solvent.
Dip the new rear main seal halves in motor oil. Slide the bottom half into the rear main bearing cap. Be sure it is facing the right way, with the lip of the seal facing the front of the engine. The flat part of the seal that fits into the groove of the rear main bearing cap faces the rear of the engine.
Install the upper half of the rear main bearing seal by placing the installation tool between the solid flat part of the seal and the groove in the engine block. The installation tool is a very small, thin piece of metal that will prevent the sharp edge of the engine block from cutting or scraping the rubber on the flat part of the seal. The flat bead of the seal faces the rear of the engine. Push the seal around the groove until it is flush with the engine block on both sides.
Place a small 1/16-inch bead of oil resistant silicone RTV sealant on the rear of the engine block in the notch where the rear main bearing cap will seat. Do not run the bead of sealant the whole length of the notch and do not put sealant in the part of the notch where the crankshaft sits in the rear main bearing. The sealant goes in the rear half of the notch.
Install the rear main bearing cap. Tighten the bolts until the rear main bearing cap is seated against the engine block. Tighten the remaining main bearing caps to re-seat them. Use a torque wrench to tighten the main bearing caps to the specified torque.
Apply gasket sealer to the sides of the oil pan. Place the oil pan gasket side sections onto the oil pan. Apply gasket sealer to the top of the side sections. The oil pan gasket kit consists of four pieces: two side pieces and a front and rear piece. The front and rear oil pan pieces are molded rubber. Place a dab of the silicone RTV sealer on the side pieces of the oil pan gasket where the ends of the front and rear pieces will contact them. Set the oil pan against the engine block and install the bolts. Tighten the bolts until the side pieces of the gasket just start to bulge out from between the oil pan and the engine block.
Fill the engine with motor oil. Lower the vehicle, start the engine and check for leaks.
