One of the most dreaded but common preventative maintenance items for the BMW E9X M3 with the S65 V8 are the rod bearings. This customer wanted to try tracking his E92 M3 but wanted to make sure the rod bearings were good to go beforehand. At one local track day in 2021, we saw 2 separate E90 M3's spin factory rod bearings at Mission Raceway which results in needing a full engine replacement. Engine replacement can easily cost upwards of $25K (CAD) and stock for healthy used blocks continues to dwindle as time goes by.
In our opinion rod bearings should be upgraded/replaced regardless of whether or not an owner intends on tracking. Plenty have spun rod bearings on the street as well. They should not be viewed necessarily as a design flaw but as a maintenance item instead. For this customer we went with upgraded BE Rod bearings and rod bolts which should fare better for track use than OEM BMW.
For DCT cars we recommend also doing the DCT side seal and DCT fluid while the subframe is dropped to save a bit of labour down the road. DCT side seal and lower pans commonly leak even after just a few thousand kms. There are upgraded covers that are much better than OEM/OE replacement covers if longevity is a concern.
A few other maintenance items we did during the rod bearing job:
- Motor Mounts: these are common failure points for S65 engines, replacements from Corteco or Vaico are very affordable but upgraded ones like 034 Motorsports are great as well for a stiffer mount
- All fluids: Engine oil is a given since the pan needs to be dropped but coolant and power steering fluid would need to be changed as well for the rod bearing job
- Various bolts + gaskets: We went with genuine BMW oil pan bolts (various sizes) and also replaced things like the oil filter housing gasket, oil cooler hose gaskets
- Alignment: As the front subframe needs to be dropped and the steering rack will be moved around, an alignment is recommended
- Oil Filler Cap: Anyone can replace this so this isn't something exclusive to a rod bearing job, but factory oil filler caps tend to fail resulting in some seepage that is very visible (see pictures below). This is a very cheap part to replace and will help keep your engine bay looking fresh and prevent oil leaks.
All in all the cost of the upgrade should range from $3500-4500 depending on what various additional maintenance items an owner wishes to address and specific parts cost differences. As preventative maintenance to be done every couple of years, we think it's a reasonable amount to budget for as upgraded bearings should last longer and be more suitable for motorsports use and enthusiast driving. Engine replacement will easily cost more than half of what the average E9X M3 goes for and one should not purchase one of these higher strung sports cars expecting to maintain them like a regular 3 series. The S65 M3's are inherently higher maintenance but it's the price paid for a very special motor.
