Quote:
Originally Posted by RossBMWZseries
So, where can we read about this S54 issue, like a "S54 bearing 101 for dummies", where it all began and how all this functions; asking for a friend................
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I'm not sure if you're pulling my leg or not, but here is a link to get you started:
http://www.m3post.com/forums/showthread.php?t=887379
If you want a quick summary of the theories for premature bearing wear, they are:
Intense Use (High RPM, Tracked, WOT) - Suspect tolerances are too tight to retain oil film at highest RPMs. Suspect rods actually distort at highest RPMs causing metal on metal contact. Could be combo of the two. Several engine builders believe bearings are simply too narrow for application, and upgrading to wider bearings and new rods, etc is the only permanent fix, but costs $$$$.
Driver Use (RPM rarely > 6000, not tracked) - Suspect cold start has lack of lubrication on bearing surface, so first few rotations are metal on metal. This would explain why some daily driven S54 engines show rather extreme bearing wear at low mileage. Another idea I floated was that engine lugging may be occurring frequently with some drivers not that experienced with manual transmissions. It may never be driven hard, but it might as well be, because George lugs a cold engine every morning getting up his inclined driveway, so by 30K, his bearings look like crap.
Fixes Replace with OEM bearings every 50K or less if tracked. OEM bearings are treated like a maintenance item. WPC Treated OEM bearings - unknown? Maybe will get you to 80K, 100K if not tracked? WPC is much slicker and retains oil better, but clearance is the same. Some other shops sell a coated bearing. Fear is that the coating actually adds to thickness making clearance issue worse, but might help with the dry start situation. WPC is not thicker. A fairly new option, BE Bearings, are from the same company that makes the OEM bearings (Clevite). BE requested a custom spec. They take down the initial thickness of the OEM bearing, add on an anti-friction layer, so the finished thickness produces close to the original OEM clearance, but very slightly more clearance to allow a little thicker oil layer. Same lead, copper layering, so oil analysis can be used. This is what I plan to use. The bearing variance is also less on the BE bearings.
Edit: The statement below is likely not true and was posted in error. BE did spec special ARP fasteners for the S65, but until I receive further information from BE-Bearings, I think the S54 M10 bolts used in our engines are the standard ARP-2000 bolts.
BE also spec'd some ARP rod bolts for the S54 that supposedly solve the stretch problems with the original ARP bolts.
Salty