Here at Lang Racing we’ve grown accustomed to the intense maintenance that BMW Motorsport engines require. The rod bearings on the S85 engines don’t seem to last anywhere near as long as they do on the standard 5 or 6 series engines. Since the labor is straightforward to replace the rod bearings on this V10 we have begun offering this service for our customers. This preventative maintenance is best to do at your next oil change interval and every 60k to 100k miles that your engine runs.
We like to use our custom sized ACL Rod Bearing Set. We have found that standard bearings run a little bit tight for our liking, so we worked with ACL to develop a custom solution that creates the rod bearing clearance we like to see. Our ACL bearing solution is not only high quality, but economical. Bearing clearance is similar to other bearings on the market but at a lower price point. We also have found the Carrillo WMC for the S65 rod bolt to be a good aftermarket replacement bolt for this rod. With careful in house measurements we were able to determine the correct torque procedure for installing the Carrillo bolt in the stock rod that does not distort the big end rod bore roundness. This is critical in the stock rod because we can’t measure rod bolt stretch like we typically would on any other engine or in aftermarket rods. While the stock bolt is at yield at the torque spec BMW uses for this rod, the Carrillo bolt is well within its stretch specifications and can be reused in the future if replacement is done again.
Of course we do realize that the stock rod bolts have not been failing in these engines and are economical so we also stock those bolts for this job as well they are the more popular choice when performing this service.
Another common maintenance item on the S85 engines is the high pressure VANOS line that runs inside the engine. This line can potentially develop a leak and cause loss of oil pressure. Since the leak is internal to the engine it is almost undetectable and will cause a decrease in oil pressure. We typically remove the VANOS oil pump and replace this line when doing rod bearing maintenance work. This requires setting the valve lash on the VANOS oil pump gear upon replacement of the oil pump. We typically also replace the engine mounts at this point if they have not recently been replaced as they are extremely easy to access.
And finally, we find it very common to find that these S85 oil pans over the years have taken some abuse and have had their oil drain lines stripped out partially or fully. When we have the oil pan off the car this is the ideal time to mount it up to our in house mill and resurface the sealing surface as well as taking the time to drill, tap, and helicoil or timesert the oil pan. Doing this process on the mill ensures that the drain plug is perfectly flush with the sealing surface and will never leak in the future.
Please contact us to schedule your appointment to have your rod bearing service performed.