Replacing a rear main seal on most engines is a daunting job; not because the seal itself is difficult to replace, but due to the laborious task of getting to it. The seal rides on the rear of the engine’s crankshaft; you can access it only by removing the transmission. While replacing the rear main seal on a Lincoln Town Car is not a job for the faint of heart, you can do this in a weekend with basic repair skills, a decent set of tools and someone to lend a hand.
Set the parking brake on the Town Car, and place the wheel chocks at both front and back of the driver’s-side rear tire.
Put your safety glasses on, and jack up the front of the Town Car far enough to allow you to place jack stands under the front frame on both sides. Repeat this in the rear of the vehicle so that the entire car is off the ground and resting securely on jack stands, one at each corner of the frame. Make sure the vehicle is sitting high enough that you can pull the transmission out from underneath it if necessary.
Slide under and unbolt the drive shaft, using your socket set. Once you have both ends unbolted, move the drive shaft out of the way.
Slide the jack in, and raise it up so that it is resting a few inches below the transmission pan. Set the two-by-four on the jack head, and raise the jack up until the board contacts the transmission. Disconnect the transmission cooler lines and wiring harness. Wrap a rag around the transmission cooler lines until you remount them, which will prevent dirt from getting inside the lines.
Remove the bolts holding the transmission bell housing to the back of the engine, saving the top bolts for last. You will need the socket extension to reach those bolts.
Unbolt the transmission mount and remove it.
Use the jack to lower the transmission. You will need your helper for this. Get on opposite sides and coax the transmission away from the engine and downward until it clears the chassis. Once the transmission has cleared enough of the undercarriage, remove the shift linkage as well.
Carefully remove the rear main seal from the back of the engine, using the seal puller. Use extreme care so you do not nick the end of the crankshaft; if you do, the engine will leak oil as soon as you start it up again.
Hold the new rear main seal up to where it mounts. Rest a large socket over the new rear main seal. Carefully tap the socket with the rubber mallet until it seats into the engine.
Reinstall the transmission, transmission mount and drive shaft. Reconnect the transmission cooler lines, wiring harness and shift linkage.
Start the engine and let it run for 15 seconds, then shut it off. Check the oil level and add accordingly.
Start the engine again and let it run for a few minutes. Shut it back off, and climb underneath and inspect for leaks. Peer through the inspection cover on the bottom of the transmission bell housing to see the rear main.
Carefully use the jack to lower the Town Car off the jack stands and back onto the ground. Run the engine for 15 minutes; while it is running, put your foot on the brake and shift the transmission through all the gears and back to "Park." Shut the engine off, recheck the oil and transmission fluid levels, and recheck for leaks.
