Rear Main Seal, Oil Pan and Gasket Replacement

Mo Lynn

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Jun 30, 2020
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10
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PA
Rear Main Seal, New Oil Pan and Gasket.
After many viewings on the subject, I decided to tackle it today. Let me say, the clips help but left a lot to chance, so I thought I'd share my experience on my '04 TJ 4.0, 5 sp. with 104k miles. Drain the oil early so you have less dripping on you. And also disconnect the ground on your battery.
1) Remove the tranny skid plate and prop up the front of the tranny. 3/4 main bolts (6) and 14 mm trans nuts (4). Now you'll have access to the muffler flange.
2) No one mentions the exhaust. Mine was the y cats, so 4 flange bolts. Totally remove the front section of cats and drop it all the way down. No clearance unless you doHave a 3/8 15 mm swivel cause it made it easier ( not easy though) and a 15mm for the muffler flange. Unplug the leads to the 2 lower O2 sensors before lowering. Help is good when it comes loose!
3) Remove starter and set it on the frame. Had 2 different size bolts, 9/16 and 3/4.
4) Drop oil pan 28 x 7/16 bolts. Take your new gasket out and lay it on the box it came in. Mark the holes and drill them out so you have a storage spot for all the bolts and it'll keep them in the exact location for reinstalling. Mark front , back, left and right on the box pattern. Saves a boat load of time! Also, there is a tranny cover on the rear of the pan, it may look like you can't get to those bolts but it's only crud covering bolts.
5) Drop the girdle that runs the length of the bottom of the engine 14 x 9/16 nuts.
6) Now you have access to the rear main cap. Remove 2 bolts and don't use an impact wrench, just a breaker bar. Wiggle it from front back and it'll drop, make sure it doesn't break away and hit concrete, just keep a hand on it, may need a screw driver to pry it back and forth (gently). Both seals came out very easily. Follow those other videos on how to treat the seals for installation and cap conditioning. The Fel Pro tab works great to install the upper half seal, use it. Make sure you use the correct RTV on the cap (Anaerobic). Install the lower cap back to the upper, bolts tighten to 80 lbs.
7) Install the girdle, 14 x 9/16 at 35 lbs torque.
8) Clean the mating surfaces on the block and oil pan ( I just spent $50 on a new one). Install the Fel Pro tabs that came with the gasket to the four corners of the block. I recommend just a couple of turns and not seated all the way ( Couldn't get one out and had to remove the oil pan and gasket to get it out, aaarrggghhhh!)
9) Install gasket with RTV on the correct spots, then the oil pan, again with RTV on the correct spots too. Install 28 bolts. Check on the torque.
10) Reinstall starter, exhaust, plug in 2 x O2 sensors, tranny skid plate, change oil filter, add new oil, connect battery and viola, you're done. $100 in parts and saved maybe $500 in labor, maybe more
 
Seriously debating doing this myself now that the weather is nice. How long did it take to do?
 
Seriously debating doing this myself now that the weather is nice. How long did it take to do?
It all depends on how prepared you are and if everything goes to plan. Could be a couple hours to several hours. Took me several hours the first time, but when I do it again (because it started leaking worse after I changed it), I will be much quicker now that I have done it once. A common hangup people run into is rusted exhaust manifold to Y-pipe bolts. Hit them with penetrating oil and make sure you can remove them before you get neck-deep into the project. Other than that, reading the procedure and having all the tools you'll need right beside you will help things go smoothly.