Totallyrad

I was having a clutch issue and needed to drop the tranny. As a part of the process, what a great time to change the leaking rear main seal since the hard part is getting to the seal. I'll apologize now for not shooting a picture of the seal removal process but there is another thread here that has them. The seal removal process is to drill 2 holes in the seal 180* from each other, insert screws and pry the seal out. One important note, make sure you drill the hole dead center in the seal. It's important because you don't want to damage the face of either the crank or the outer mating surface.

Once you get the seal out, this is what you're looking at.


Once you have the seal out, use something like brake cleaner on a clean, lint free rag to clean the mating surfaces. Both faces should be clean and dry. Do not use any lubricant to help install the seal. The replacement seal will come to you with an installation ring made of metal and a plastic guide ring to slide the seal over the crank. Leave the plastic guide in place and remove the metal ring and set it aside. Carefully ease the plastic guide with the seal over the end of the crank with the taper facing the front of the engine. This is what you should see.


Once the front of the guide is inserted about 1/8 of an inch over the crank, carefully push the seal in buy hand as far as you can but take care to keep the seal square in the hole. Now remove the plastic guide. This is the view now.


Now comes the fun part. If you were to follow the instructions in the FSM and the instructions that came with the seal, you would now be reaching for a hammer. And, if your luck is like mine, you'll probably be cussing a blue streak in about 2 more minutes because despite your best efforts, the seal went in deep in one spot and no longer is square in the hole and that won't work. The seal must go in straight and true or it will leak in short order. It's also not recoverable so the only way to remove it is to destroy it. As embarrassing as it is, I had to ruin 2 before I threw away the instructions and worked the problem on the third. At $80 a pop you can bet I was not happy. The following steps will prevent you from paying for the lesson like I did.

OK, back to work. The next thing you need is a dozen or so heavy flat washers. I had some 3/4" ones in the bolt bin so I was set.


Grab one of the flywheel bolts and load up some washers. I used three.


Now start that bolt in the top most hole in the crank. Only run it in a thread or two, then grab the metal installation tool that came with the seal. Slip the ring behind the washers and let it hang there.


Now repeat the process at the 3, 6, and 9 o'clock positions.


Once you have all the bolts started, center the installation ring on the seal and tighten all 4 bolts finger tight. Now grab a wrench, and going around the clock, tighten each bolt 1/4 turn each. I pulled the seal in about half way and removed the bolts just to check that it was actually going in square, then reinserted the bolts and continued until the washers had bottomed out.


Once they had, I put a ball-peen hammer against the installation tool and struck it with another hammer until the seal seated the last .020".


Now remove the bolts and this is what you have, a perfectly inserted rear main seal that only took about 10 minutes to install and most importantly, only one seal.

Nomo47rh

Thank you soo much for that write up. I was ready to lose it trying to get that seal in. I actually was thinking about taking the the seal and housing to Cummins to get it installed. Worked like a charm. You saved my bacon. . I know it’s an old post but hopefully you get this.