My 1999 2.5L has a one piece rear main seal and I think your 4.0L 2003 will certainly have the one piece rear main seal. Google your seal part number and look at it. A one piece seal comes right out the back behind the flywheel.
The oil pan does not need to be removed at all. Your one piece seal is a straightforward job but it involves removing the transmission or at least sliding it back about 1 foot to get room to pull that rear main seal out.
If you have any doubts about the condition of your clutch pressure plate or throwout bearing this is the time to change those since you will have to take them out to do a one piece rear main seal.
With my nephews help we pulled the drivelines and unbolted the tranny and had it out in about an hour and a half with two floor jacks and no tranny jack. I also utilized a 2" trucking strap at one point to support the tranny and transfer case as we pulled it. I took the strap side to side on my frame and used it to keep the tranny centered and on my floor jack as it was lowered.
You will also need to support the back of your oil pan. If you don't have another jack you can cut a 2x4 to proper length and place it between the floor and the rear of your oil pan. The rear of the engine will drop and maybe break your motor mounts if you do not do this.
We had the entire jeep up on Jack Stands, I think the tires were about 8" off the ground, gave us clearance to work.
Some of the top tranny bolts were hard to reach but I took all of my extensions, maybe 30" total with a swivel at the socket and was able to take out the bolts from a long way away quickly. Going back in I did the same thing but put some painters tape on the bolt head to make it stay in my socket while I reached way up there to the bolt holes.
The tape works wonders for this purpose. Once the bolt is installed just wiggle it and you can pull the socket off.
The one piece seals are unique, with your crankshaft in place you will have a challenge pulling out your old bad seal.
I have pulled several over the years and the easy way for me is to drill a self tapping seal into the body of the old seal and then use a pry bar to pry out the seal. You have to be very careful of the location you drill. If you mess up you can scratch the crank seal surface. On the other side you can damage the seal surface in your block. Knowing this you drill in the middle of the metal seal case, leave the screw a little loose so you have a little surface area to slip your pry bar inside to pry it out. I use a battery powered drill on high speed to get the self tapping screw drilled in.
On a few seals the first screw stripped out but it did move the seal a little. I just drilled another and tried again.
Once it took three tries but every time I got it out with no damage to the crank or block. Once The seal was so tough I put a screw on each side and pried on both at the same time with two pry bars, it came out. There may be a special seal removal tool built to take these out but this method worked just fine. I added a picture of the pry bar type I used and the specific screws, I like the screw with the pointed tip it holds better, they also have screws with a small drill head, those do not hold as well and stripped out right away when I tried this method.
Some guys pound a screwdriver through the seal case to pry it out, I think the screw method is safer.
The Screw tip also works on the pinion seals which can be a little hard to pull.
BTW: National makes a Teflon rear main seal and those things never leak unless you mess up the installation.
If you have not installed a teflon seal do some reading or ask on here and I can offer installation information.
Teflon seals come with a plastic installation sleeve/tool in the seal. You slip the plastic sleeve over the crankshaft and use it to expand the seal over the crank on install, once fully installed you grab the plastic installation tool with plyers and pull it out. This tool keeps the soft teflon from being scratched on install, you must use the tool with teflon seals. These need to go in clean and dry, no grease or oil on the crankshaft or the sealing surface of the seal. On the Outer Diameter of the seal you can use a little oil to make the outer diameter of the seal, rubber surface slip into your block. The dry teflon will impregnate into your clean dry crankshaft and you have teflon rubbing against the crank, as the crank rotates teflon impregnates into the crank surface and the seal will seal up and have zero drag. These cost about twice as much as the standard seal but the quality is so much better. They can last several hundred thousand miles with no leak. Every Diesel engine built has used teflon rear main seals for the durability since about 1995. The only ones I ever hear of leaking are from people who install them and ignore the install dry and clean instructions, they use oil or grease on the sealing lip and it keeps the teflon from impregnating like they need to so they fail.
There must be Youtube videos of a teflon seal install by now.
No joke the money spent on teflon rear main seals is money very well spent.
For those with the older engines using 2 piece rear main seals Teflon is not available, this is only for newer engines with the One Piece seal. Dang, that is a lot of words, Hope it helps
Mark
