Replacing rear main seal?

I am going to be replacing the oil pan gasket tomorrow. Want to replace the rear main seal while in there....any tricks or booby traps?

lots of rags. gotta soap up one side, forgot which. google it and you'll find 1000 write ups

A couple of tips that helped me:

1) Buy an extra seal in case you fubar the first attempt.
2) Soak the upper seal (engine block side) in dish soap such as Dawn dish soap
3) After installing the lower seal in the main cap don't forget to apply rtv sealant to the
corners of the seal
4) Torque the main cap in stages
5) I applied rtv sealant to the oil pan gasket and it held it in place making the install
easier and guaranteeing a better seal

Hope this helps

Be sure to use a brass drift to knock the old seal out. Using a steel punch will scar the crank and it will likely leak more after you are done.

thanks for the pointers

Might want to clean the oil pump pickup screen and re-torque your rod and main caps too.

its one hell of a messy job. so wear old clothes.

one thing ive found helps A LOT in keeping clean is letting it drain as long as possible. last time i did mine i let it drain, and then pulled the oil pan, and let it sit in the garage for about 12 hours. that lets as much of the oil drip off the crank and everything else as possible.

if you drain it, and then immediately start doing the rear main seal youll be getting oil drops in your eyes and mouth the entire time your under it making it a real PITA job.

if you can find a way to keep clean during the job then it makes it much easier.

about the soap. im not sure if i was doing something wrong, or if it was soap related, but i put in 2 seals using soap and they leaked far worse then it had to begin with. used some bearing grease the 3rd time and its like new.

that said, its not a job you really want to ever have to do....let alone more then once, so take your time, and do it right

yeah, use moly assembly lube is what I've been told... I'm a little squeamish about getting soap (even a small amount) in my oil. Also make sure you get the right seal, most 4.0L engines use a Fel-Pro BS40612 but a few years (99? 00? 01? I forget which. There is a thread about it somewhere here, search for BS40183) use the BS40183 rear main seal.

EDIT: here's the thread http://www.naxja.org/forum/showthread.php?t=1006852 - I was blatantly wrong on my first post in it... live and learn I guess!

I didn't end up doing it. O'Reilly's only had 1 RMS and I am working on my only working vehicle for a family of 4. I will wait for O"Reilly's to get the 2nd RMS in before attempting this. I did replace the valve cover gasket, which was leaking. Will clean off the entire engine with Automotive Simple Green and confirm before the weekend if the oil all over everything was just the valve cover leak, or if it is a combination of the Valve Cover and Oil Pan gasket. No need to dig in, if I don't have to.

If you are having a difficult time removing the seal with a brass punch and it just seems stuck, loosen (but do not remove) the other main bearing bolts. This will drop the crank down a hair and loosen up the RMS for you. I only needed to do this on one 4.0L rear main install - the other four or so I've done came out pretty easy with a brass punch.

Mudshack said:

I didn't end up doing it. O'Reilly's only had 1 RMS and I am working on my only working vehicle for a family of 4. I will wait for O"Reilly's to get the 2nd RMS in before attempting this. I did replace the valve cover gasket, which was leaking. Will clean off the entire engine with Automotive Simple Green and confirm before the weekend if the oil all over everything was just the valve cover leak, or if it is a combination of the Valve Cover and Oil Pan gasket. No need to dig in, if I don't have to.

Click to expand...

well what I thought was a main seal leak was just some of the PCV plumbing being clogged up causing overpreasurization of the oil system. Check it out.