BMW Tech Corner - S65 Connecting Rod Bearing Failure
Its no secret that the powerful S65 V8 that came in the e90 e92 and e93 BMW M3 (2008-2013) has some known mechanical issues. (Like any high performance engine) One of the most troublesome is the premature failure of the connecting rod bearings.
Research shows that BMW could have added a bit more clearance on the upper shell of the bearing to allow more sufficient oil flow. (We found a pretty extensive write-up about this S65 rod bearing issue at m3post.com.) Some people have tried running thinner than recommended oil as a “band-aid fix” for the issue. Of course, this didn’t help the issue and may even have made it worse, not to mention that a lot of internal components of the engine operate through oil pressure; using a thinner (lighter weight) oil may hinder the overall performance of the engine.
Brian brought his gorgeous, frozen blue E92 M3 in for a check engine light. After fixing a simple failed O-ring on one of the throttle bodies, Brian asked us to replace the rod bearings as preventative maintenance. His car has just over 58k miles. We recommend the bearing replacement at 60k miles. Since he lives two hours away he asked us to replace the bearings now while we had the car.
The procedure is fairly straight forward, first of course we drain the oil, next we support the engine from the top using an engine brace. We remove the subframe, then the oil pan. The engine is rotated to bring the pistons to BDC (bottom dead center) from front to back. The rod bearing caps are marked so they go back on exactly how they were removed. The old bearings come out and the new BE Bearings go in. We lubricate the new bearings with assembly lube, and tighten the caps back down with ARP bolts torqued to ARP’s specifications then mark the bolt to identify it as “torqued”. The engine is then reassembled with a new oil pan gasket and all new hardware. The subframe is reinstalled, new oil and filter is installed. And we’re done!
After the new bearings are installed we suggest allowing a 1200 mile break in period. We ask the client to try to keep the engine below 4000 rpms and no hard accelerations.
The total cost of this repair is roughly $2500.00. The cost of a new engine is roughly $25,000.00. This maintenance is a small price to pay to get many more years of enjoyment out of the one and only V8 powered M3. Call, text or email today to set up an appointment to get your car on our schedule!