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Old 08-07-2010, 05:03 PM   #1
TitaniumCranium
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Join Date: Apr 2005
Location: Seattle / Sequim
Posts: 3,198
My Ride: 2002 BMW 330Ci
DIY - Rear Main Seal

This DIY assumes you already have the transmission out for some other reason; transmission swap, clutch replacement, torque converter replacement, etc. I posted this up because I couldn't find one but I saw a few people asking for one.

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The rear main seal is super easy to do. The kit that BMW provides has everything you need; the seal, which is already installed in the frame it goes into, the bolts, the gasket, and a plastic guide cone so that you can easily and without damage install the seal. The ETK refers to the kit as "set of covers" and the part number is 11141438274. The part I referenced covers all E46's from M52's to M54's (Z3's and 5er's too).


^ The first thing you have to do is get the 8 x grade 10.9 bolts out so that you can remove the flywheel. Lock the flywheel in place as shown so that you don't need to buy the special BMW tool that is used for this purpose. I used a breaker bar and a 1/2" drive socket to pull these out as they are tight and difficult to break loose!


^ With the flywheel off you can now get to the rear main seal. The seal before I replaced it.


^ With the cap removed and surface clean. Note the two oil pan bolts that come in to the bottom of the RMS frame.


^ New cap (with seal) ready to go in with white plastic guide cone (included in kit).


^ New RMS installed. Note - I used a thin film of Permatex copper high temp silicone gasket sealant on the bottom of the cap to ensure that no oil leaks from the oil pan gasket as you're not replacing that piece at the same time.

Difficulty level 2 out of 10.

If you are in the process of replacing the clutch you already dropped the tranny and that is definately the hardest part. Now you just need to remove the 8 x grade 10.9 bolts that secure the flywheel to the output shaft of the motor. Then pull the flywheel off and the rear main seal is right there. Remove the 8 bolts that hold it on, six on the front (rear of the motor) and two from the bottom. I removed the six upper bolts first, then I backed off the bottom bolts just a few turns. I tapped them just a bit with a hammer and the cap popped off from the block. Don't use any force here - all you're doing is breaking the cap from the gasket a bit, you don't want to bend the hollow dowels that align everything.

Installation is too easy - the kit comes with the gasket. You line it up with the bolt holes on the block and it just fits over the hollow dowels. Smear a thin film of Permatex copper high-temp gasket sealant (or other appropriate sealant) on the bottom of the cap. Lightly lube the seal with oil. The kit also comes with a plastic guide cone that you place inside the seal - I put a film of oil on this too. Place the assembly up to the outbut shaft of the motor, push evenly and not very hard. It will slip right onto the output shaft and all you have left is to bolt it up.

The bolts all come with thread locking compound on them already. I think you have to reuse the long ones on the bottom so I used a little bit of blue threadlock gel on them. I bolted the bottom up just barely snug first. Then I put the four 10mm upper bolts in first and also just snugged them up. I put the remaining two 13mm bolts in and also just snugged them up - I don't know just a few inch pounds of torque. There are no clear instructions for this anywhere that I found so I went with logic. I tightend the bottom bolts to 6 ft/lbs to bring the cap down to the same level as the rest of the engine on the oil pan (fractions of a mm). I figured the 13mm bolts would pull the cap to the crush gasket with ease even with the bottom bolts installed because I can put 16-18 ft/lbs on them and the cap should sit where it is supposed to. After that I just tightened all the bolts to spec and you're done.

Cheers and GL
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Last edited by TitaniumCranium; 08-07-2010 at 08:11 PM.
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