[johnd89]

Hello,
It looks like my dual mass flywheel failed. I am gearing up for an eventual replacement of the rear main seal.

I have called the dealer and gave my VIN number. My car was made Dec 05.
I then inquired about the rear main seal. They said that they have two p/n listed one thicker (12mm) and one narrower (8mm). He said that they use the narrower one.
He seemed to imply that they now use the narrower one even if say I would have my car done by them.

I have looked this up and indeed from Jan 09 they used the narrower one.
Besides the width, the newer one looks like a normal seal in the sense that it does not have the two grooves to accomodate for the crankcase seams.
The procedure asks for two component Loctite seal (a primer and a seal in a syringe). I am guessing this is for the pre 09 seal with grooves.
I tend to go with the post 09 seal and smear some permatex red where I have the crankcase seams.

I am also assuming for the seal without the grooves you wouldnt have where to inject the sealant.

It would be cool if we could find out if that crankcase seam is any different in between the post 09 cars and pre 09 ones.

Thanks so much for any clarification.

[Efthreeoh]

Let me take a different approach here for you. Consider not replacing the rear crank seal. If you go ask professional mechanics, they will tell you they do not touch the rear crank seal when replacing the flywheel if the seal is not leaking. The reason for this is that removing the non-leaking original seal introduces a 50/50 chance the new seal will leak post installation.

I replaced my clutch and DMF in January 2016 at 293,000 miles. I also had the common oil pan gasket leak. I had oil bleeding from the bell housing vent hole and thought the RMS was leaking. So I was prepared to remove and replace the seal during the clutch change. After pulling the flywheel I found the crank seal dry as if it was brand new. The oil coming from the bell housing was sourced from the pan gasket leak not the RMS.

Considering should use the special tools BMW recommends to remove and replace the seal and the 2-part sealant application to assure the best leak-free installation, I'd recommend not replacing the seal if it is not leaking. I didn't. My car is now at 361,000 and the RMS is still leak free. Here a pic of it at 293,000 miles.

The N52 block was not changed, the crankcase seam is the same pre and post '09. I bought both seals in prep for my clutch job, other than the 12 vs. 8 MM they looked the same.

[johnd89]

Words of wisdom
Thank you!
I did ordered the 8mm one to have it on hand.

I have broken two (out of 8) bolts which hold the reinforcement plate to the floor pan (to remove exhaust). They turn up to a point when it gets harder... If I could gain access on the other side to pass a steel brush over the exposed threads/squirt some penetrant oil it would work.
Now for the question: are these nuts/bolt exposed threads visible from any angle or captive like in between two folds of sheet metal?
Thanks again

[Efthreeoh]

Originally Posted by johnd89

Words of wisdom
Thank you!
I did ordered the 8mm one to have it on hand.

I have broken two (out of 8) bolts which hold the reinforcement plate to the floor pan (to remove exhaust). They turn up to a point when it gets harder... If I could gain access on the other side to pass a steel brush over the exposed threads/squirt some penetrant oil it would work.
Now for the question: are these nuts/bolt exposed threads visible from any angle or captive like in between two folds of sheet metal?
Thanks again

Lordy, does that sound like a tough situation. I've always removed mine with an air impact gun and Kroil, and never yet had an issue. The body nuts are captive to the body floor pan. I'd bet you could pull the carpet out to get to the top side. In the DIY section there are several DIYs on removing the interior. You may find some photos in those DIY threads that can confirm the reinforcement bolts thread up through the floor pan. An idea I have is with one of the bolts removed, can you push a small screwdriver or pick up through the captive nut in the body and get soft purchase on the carpet? I've never tried it. Or, if there is an open bolt hole to one of the stuck bolts, just spray a bunch of penetrating oil in it to try and reach the stuck fastener.

Once you get the bolts out, lather them up with anti-seize when you re-install them.

[johnd89]

Hi,
Thanks for your reply and Happy new year!
I have removed the large underbody panels and gained access to two large holes and two small ones in the vicinity of these nuts (see pic). Was able to squirt them with PB blaster and took my time and eventually they did came out. Gotta try and do something for the broken ones now.
Thanks again.