While looking at the Jeep for the first time, the owner informed me that it had an oil leak and that it was the valve cover gasket. This is my fourth XJ, I'm not new to leaky 4.0L's by any means. I knew there was a pretty good chance in addition to the valve cover that the rear main seal was probably leaking too.
I set aside a day this week to get the leaks under control, valve cover gasket, rear main seal, and oil pan gasket. I can live with a small drip, but Black Betty was leaving a pretty good sized puddle everywhere she went.
Step one, you will need as much clearance as possible, I set the body on jack stands and then let the axle droop. Even then, I knew it wasn't going to be fun fishing out the oil pan.
Supplies needed.
I started with the valve cover gasket first. Remove the throttle cable linkage, cruise control linkage, and kick down cable from the valve cover. I disconnected the CCV hoses, and didn't mess with the grommets in the valve cover. Then it's just a matter of removing the bolts around the valve cover (7/16 socket), and gently prying it loose.
Clean the surfaces. I used a vacuum as I scraped the head to prevent junk from falling into the rockers.
Install new gasket. RTV isn't necessary, but I applied a thin layer to both sides.
I cleaned up the valve cover in some solvent, and then reinstalled it. I read on the internet to torque to 55 in/lbs so I figured that must be true. I started from the middle, alternating sides, and working outward. Valve cover gasket, check.
The next chore was the rear main seal and oil pan gasket combo. Start by removing all the pan bolts, (7/16" and four 1/2"). Getting the oil pan out of the vehicle is not an easy task on a stock vehicle. Even with the axle at full droop, I had to disconnect the drag link at the pitman arm, and track bar at the axle to gain enough clearance to fish it out. You will also need to remove the starter, and possibly loosen the exhaust manifold flange (I didn't). After all that, you will have a disgusting oily mess of trophy on the ground.
On the 1996 and newer motors a "main bearing girdle" was added to the lower end that ties all the main bearings together. It's held on with 9/16" nuts on each main bearing stud. Remove the nuts, and remove the girdle. The rear main seal is located under the last main bearing cap at the back of the block.
Using a 13/16 deep socket, remove the main bearing cap. Inside the cap you will then see the lower half of the rear main seal, and the upper seal half in still in the block.
Using a punch
carefully tap the seal on one side to drive it out the other. Take careful consideration to not chip the block or score the crankshaft. Ideally you should use a brass punch. Patience is key. After you get the seal driven out a bit, you can grab it with needle nose the rest of the way.
The new lower half of the seal installs in the main bearing cap. Be sure to pre-lube the seal. I apply a thin amount of RTV on the corners where the two halves meet. The new upper half needs to be driven into the block. Again, pre-lube the seal (I used dish soap), and use the supplied plastic "shoe horn" to prevent catching an edge on the block. After the seals are installed, bolt the main bearing cap back into place, and torque to 80 ft/lbs.
Reinstall the main bearing girdle. I torqued the all the nuts to 40 ft/lbs.
I then spent some time cleaning up the oil pan. The sludge caked on the outside was atrocious. After you have the seal surface prepped, installed the new gasket. Again, RTV is not needed, but I applied a thin layer anyways.
The next part is not fun. You will need to somehow fish your oil pan back up around the axle, and up to the block, while trying not to ruin the new gasket. It was during this step that I contemplated just removing the entire axle, after nearly convincing myself this task was impossible. I eventually got the oil pan lined up, double checked to make sure the gasket was still in place, and then began finger tightening the bolts. The 7/16" bolts will need to be torqued to 84 in/lbs, while the 1/2" bolts will get the 132 in/lb treatment. Again, don't tighten in a circular patten, skip around.
The last task of the day was to add new oil, and change the oil filter. Six quarts of 10W30, a WIX#51515 filter, and I was done. Since I removed the oil pan, and oil pump temporarily, I wanted to prime the oil system first before firing the motor. I did this by removing the ASD relay from the under hood relay box. The ASD cuts fuel and spark to the motor allowing you to crank it over to prime the system. After awhile of cranking, I reinstalled the ASD relay, and fired the motor.
I was pleased to see no apparent leaks immediately after starting the Jeep. I must have done something right. However, after cleaning up my tools, and letting it sit I had a small puddle of oil under the oil filter. After some investigating I noticed a steady drip of oil coming out of the electrical connector for the oil pressure sending unit. Apparently the internal seal had gone bad. The steady drip had caused one hell of a mess over time. I swapped out the sender for a new one, and I think at this time I can say I got the leaks under control.
