Crank pulley seal damaged?

xPistolll · 12-14-2023, 08:03 PM

I was replacing my belt and pulleys due to serpentine belt shredding mid drive. Its a 2011 BMW 135i M sport with the DCT and N55. I removed the 8 bolts holding the crank pulley and the pulley itself and saw no belt remnants inside and seal was not pushed back nor leaking oil, because as soon as i heard the belt hit the ground i turned the car off asap, but there is a small seal on the outside of the pulley that looks like it may be covering the bearing on the pulley? Im not sure what it is because the seal doesnt connnect to the anything on the back of the pulley, but I want to be safe and make sure this scare never happens again. Im not sure if it was caused by the belt or something from the previous owner. Car just hit 60k miles. If I need to replace it I will, but the part on FCPEuro goes for $500 for just the pulley so if I can just repair the seal or re-use it as is it would be better than throwing that money away. Heres the image of the front and back of the pulley.

FYI this is NOT about the front main seal, its about the seal on the OUTSIDE of the pulley.

rick_flying_machine · 12-15-2023, 10:29 AM

It's hard to see from your picture, but when doing my belt and pulleys, I replaced the harmonic balancer (another name for the pulley) because it was wobbling too much to my liking and felt it was inducing engine vibration.

Not sure if it's damaged in your case, but it looks overall in much better shape than mine did.

I also installed a crank seal guard (the one from Malo Industries was a good fit for my N55) as extra protection should the belt shred. Since you're in there, it might be worth it.

xPistolll · 12-16-2023, 05:51 PM

Thanks for the info Rick. Yea it doesnt look too bad at all and im not even sure if the belt caused it. I also ordered the crank seal guard from Malo so once that gets here ill install everything and watch it closely and look out for any extra vibration or wobbling. Was there any fitment issues installing your crank seal guard?

rick_flying_machine · 12-17-2023, 10:11 AM

It's been a while since I installed the guard, but there are a few diy on youtube and on the forums if I recall.

Be careful removing the 2 original aluminum bolts from the engine case. You don't want those to break in the block. Other than that, fit was very good with minimal play. Before I torqued completely the two bolts provided, I ran a piece of paper all around the gap to make sure the guard wasn't touching the crankshaft.

When retorquing the pulley, I followed a star pattern that I have found in ISTA.

12-14-2023, 08:03 PM	#1
xPistolll Registered 0 Rep 2 Posts Drives: 2011 BMW 135i Join Date: Dec 2023 Location: California iTrader: (0)	Crank pulley seal damaged? I was replacing my belt and pulleys due to serpentine belt shredding mid drive. Its a 2011 BMW 135i M sport with the DCT and N55. I removed the 8 bolts holding the crank pulley and the pulley itself and saw no belt remnants inside and seal was not pushed back nor leaking oil, because as soon as i heard the belt hit the ground i turned the car off asap, but there is a small seal on the outside of the pulley that looks like it may be covering the bearing on the pulley? Im not sure what it is because the seal doesnt connnect to the anything on the back of the pulley, but I want to be safe and make sure this scare never happens again. Im not sure if it was caused by the belt or something from the previous owner. Car just hit 60k miles. If I need to replace it I will, but the part on FCPEuro goes for $500 for just the pulley so if I can just repair the seal or re-use it as is it would be better than throwing that money away. Heres the image of the front and back of the pulley. FYI this is NOT about the front main seal, its about the seal on the OUTSIDE of the pulley. Attached Images
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12-15-2023, 10:29 AM	#2
rick_flying_machine New Member 12 Rep 15 Posts Drives: 2011 135i M sport 6spd Join Date: Mar 2023 Location: Montreal iTrader: (0)	It's hard to see from your picture, but when doing my belt and pulleys, I replaced the harmonic balancer (another name for the pulley) because it was wobbling too much to my liking and felt it was inducing engine vibration. Not sure if it's damaged in your case, but it looks overall in much better shape than mine did. I also installed a crank seal guard (the one from Malo Industries was a good fit for my N55) as extra protection should the belt shred. Since you're in there, it might be worth it.
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12-16-2023, 05:51 PM	#3
xPistolll Registered 0 Rep 2 Posts Drives: 2011 BMW 135i Join Date: Dec 2023 Location: California iTrader: (0)	Thanks for the info Rick. Yea it doesnt look too bad at all and im not even sure if the belt caused it. I also ordered the crank seal guard from Malo so once that gets here ill install everything and watch it closely and look out for any extra vibration or wobbling. Was there any fitment issues installing your crank seal guard?
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12-17-2023, 10:11 AM	#4
rick_flying_machine New Member 12 Rep 15 Posts Drives: 2011 135i M sport 6spd Join Date: Mar 2023 Location: Montreal iTrader: (0)	It's been a while since I installed the guard, but there are a few diy on youtube and on the forums if I recall. Be careful removing the 2 original aluminum bolts from the engine case. You don't want those to break in the block. Other than that, fit was very good with minimal play. Before I torqued completely the two bolts provided, I ran a piece of paper all around the gap to make sure the guard wasn't touching the crankshaft. When retorquing the pulley, I followed a star pattern that I have found in ISTA.
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