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      01-10-2019, 10:03 AM   #1
fatty335
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Drives: e90 335i
Join Date: Apr 2018
Location: The Palmetto State

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I'm going to preventatively replace my 72K N55 rod bearings

I know this has been openly considered/discussed before by others but nobody has actually gone through with it. While the general consensus has been "if it ain't broke, don't fix it," since it's a relatively uncomplicated job and I plan to keep my N55-equipped 335i well past 100K miles, I'm going to do it. This car, like many from the early 2010s-era, was subjected to 15K OCIs which was probably not conducive to extended bearing life. I also run an MHD 1+ on what is an essentially FBO minus cat back car - again, probably not conducive to extended bearing life.

As we all know, bearing replacement is a pretty common maintenance procedure in S65 and some other BMW engines. I plan to swap identical OE bearing shell combos: violet/blue or yellow/red depending on what I find stamped on the crank. I, like most shops swapping S65 bearings OE for OE, do not plan to check each clearance with platigauge. Additionally, I will use new, OE torque-to-yield rod bolts and resist the urge to use ARP or anything else that might even slightly alter the factory clearances.

I'm collecting parts now and am curious to see how worn my 72,000+K N55 bearings are. Not sure if I'll get to this job before going on a fairly long trip in a month but, it's going to happen...
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