Rear Main Seal Leak Jeep Cherokee
Last night I did another rear mail seal on a Jeep Cherokee. I still remember the first one that I did with lots of help from my Dad. In fact he did most of the work. We could not figure out how to get the pan out from under the engine. Based on some instructions we fond on the internet at the time, he ended up unbolting the oil pump and letting it fall into the pan to get the pan out from under the Jeep.
Since that time I have done several more. Each time I find I can unbolt slightly less to get the pan out.
Once the oil was drained, I first unbolted the starter and pushed it aside. I left the electrical connections in place and just set it to the side. I should have disconnected the battery cable at the battery but I did not.
Next I unbolted all the clips holding the transmission lines in place. There are several of these that all have 8mm headed screws. This allowed the lines to be moved around as needed to maneuver the pan. Also disconnect the oxygen sensor at the connector by the pan. This will prevent possible damage to the wire when putting the pan back in.
I then removed all the bolts from the pan. There are several different sizes and types of fasteners in the pan. And some have extra clips on them. So you need to devise a method to keep track of them so they go back in the right holes. I laid them out on my work table in a pattern I could follow going back in. You will need a deep well 7/16 socket and a 1/2 inch socket to get them all out.
I had trouble with all of the double decker bolts that held clips. They all came out of the pan when I tried to undo the nut that is supposed to hold the clip. I simply left them as assemblies until time to put them back in. Then I took them apart so I could properly install the fasteners.
With all the bolts out, I tapped the pan with my fist and it separated easily. That is the nice thing about working with the later model one piece gasket. If you are doing an earlier one with the four piece gasket; be prepared to drive in a knife blade to make the pan separate. You will then have to straighten the pan once you have it off.
Getting the pan out from between the axle and the oil pump is the tricky part. Yes, it will fit if it is turned just the right way. Holding the pan by the sump and facing forward, slide the front of the pan up the track bar to the left. Pull the rear of the pan to the right so that the flange is against the bell housing. Once it is properly aligned, it will slide right out. Tapping it with a soft hammer will help align it. It is OK to flex the pan a little to get it out if necessary. Removing the shocks will allow the axle to drop to get a bit more clearance. Also, you can disconnect the track bar. However, it is not necessary to do either of those steps as the pan will come out if it is properly twisted.
The rear main seal is in the rear main cap. Use a 13/16 socket to remove the two bolts and drop the cap. The cap fits snugly so you may have to use a pry bar to work it out of the recess in the block.
The lower part of the seal can be easily removed from the cap. The upper part of the seal is a little trickier to get out. The seal is square in cross section and can be seen from below. The trick is to use a soft punch to get the seal to move around the crank shaft to rotate it out. The seal usually sticks but will move freely once it moves the first little bit.
This Jeep was particularly stubborn. I was not able to get the seal to move using my brass punch or even a screwdriver. I eventually made a drift using a piece of ¼ inch key stock. I was able to set the key stock against the seal and use a hammer to strike it firmly to get the seal moving. Once the seal moved a half inch or so, I was able to use a pair of needle nose pliers and rotate it slowly around the crank to slip it out easily.
Putting the new seal in can be tricky as well. First of all make sure it is turned the right way round. The thicker side of the seal faces the front of the engine.
Coat the seal with grease or oil. Slip the seal into the hole and begin to slowly work the seal into the slot. Push the end of the seal with one hand while holding the seal tight against the crank with the other hand. Be careful not to nick the seal. If you encounter resistance, stop and back it out some before proceeding. Once the seal is all the way in, align the ends so that they protrude the same on both sides.
Install the lower seal half in the cap. Put some RTV on the sides of the cap and push it up into the block. Install the bolts and tighten them evenly. Torque them to 80 foot pounds.
Clean the pan and the gasket surfaces thoroughly. Getting the pan back in is also tricky; especially the part about getting the gasket in at the same time. Note that you can use the newer style one piece gasket on the older pan.
To get the pan back in, twist the pan similar to how it was removed. Push the front of the pan to the left over the track bar. Don’t worry if the transmission lines end up on the wrong side of the pan. You can move them later. Pop the pan through the opening and align it with the engine. Now you can set the gasket in place and work it around the oil pickup. Sometimes it is helpful to use wire ties through a few of the holes to keep the gasket aligned as you lift it into place.
Put the bolts back into their respective holes leaving them all loose until they are all in. Note that the two at the back, have a strap that helps tighten the rear of the pan against the seal.
Tighten them all snugly and evenly. On this Jeep, I used a Felpro gasket that had metal inserts in the bolt holes to prevent crushing the gasket. The front four bolts are threaded into an aluminum part; so be careful not to over torque these. The rest are into steel and are pretty forgiving unless cross threaded.
There is one bolt that is difficult to reinstall. It is directly above the exhaust manifold and requires a swivel on the socket to get it out. Use care to make sure this bolt and the others are threaded in straight before tightening them all evenly.
Next, install clips on the studs and reattach the transmission cooling lines. Reconnect the oxygen sensor and place the wire is in the clips. Reattach the starter. Make sure the pan drain bolt is tight and then refill with oil. You may want to put in a fresh filter at the same time.