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    • BMW S85 V10 rod bearing issues becoming more prevalent as E60 M5 and E63 M6 vehicles reach higher mileage

      Motor bearings. The one main area of weakness in naturally aspirated M motors. The S54 motor in the E46 M3 was notorious for bearing issues getting an early reputation as being made out of glass as motors failed left and right. BMW eventually issued a recall and the S54 now is known as one of the greatest M motors ever produced by BMW and having a modern reputation as being very stout taking just about whatever one throws at it.

      The S85 V10 did not experience a rash of early failures like the S54 due to the bearings and neither did the S65 V8 in the E9X M3 based on it. However, as the motors reach higher mileage it is becoming clear the motors suffer from unnaturally high rod bearing wear. Why is this? One reason is that the pistons and rods may be a bit too heavy for such a high revving motor (despite BMW's marketing they go with what is cheapest in modern times) causing more wear than normal. The oiling system especially in the S65 V8 is weak so track junkies have been experiencing rod bearing wear issues.

      This problem is known in E9X M3 circles with the S65 V8 but it is now coming out with the S85 V10. Why later on the S85? Because the S85 has a slightly different oiling system (BMW went even cheaper on the S65 and this is why a dry sump oiling system is recommended for track guys) and because S85 owners only now are supercharging which puts more stress on the motor. There are more S65 V8's tracking and supercharged so the issue is far more well known with the V8 than with the V10.

      For those doubting, here is a picture of BimmerBoost user @CV10T's rod bearings at 91k miles from his S85 V10. Not particularly pretty are they?

      So what can one do to prevent premature bearing wear and even worse a motor failure? Well, frequent oil changes are recommended to remove any material in the oil. Secondly, replacing the factory bearings with a set of aftermarket bearings is a good idea. The job is not that bad as @CV10T stated replacing his bearings cost 15 hours of labor plus the cost of the bearings.

      BimmerBoost vendor VAC Motorsport has several coated bearing options available including those for the S85 V10 and S65 V8.

      Gentlemen, take care of this problem before it's too late especially if you do a lot of spirited driving at high RPM or have a power adder.


      This article was originally published in forum thread: Rod Bearing Issue becoming more common on high mileage S85s started by CV10T View original post
      Comments 39 Comments
      1. Sticky's Avatar
        Sticky -
        @Mike@VAC
      1. alex@ABRhouston's Avatar
        alex@ABRhouston -
        Our fix is replacing the bearings with proven aftermarket bearings......


        But it involves grinding the crank and replacing the rods.

        Great for an engine being built for whatever, but not very economic when just trying to fix this issue.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
        Our fix is replacing the bearings with proven aftermarket bearings......


        But it involves grinding the crank and replacing the rods.

        Great for an engine being built for whatever, but not very economic when just trying to fix this issue.
        It's more economical than replacing the motor.
      1. alex@ABRhouston's Avatar
        alex@ABRhouston -
        oh i completely agree, but its not a solution- its just a bandaid.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
        oh i completely agree, but its not a solution- its just a bandaid.
        Why just a bandaid?
      1. alex@ABRhouston's Avatar
        alex@ABRhouston -
        well, your putting in the same bearings that just went bad- you aren't solving the issue.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
        well, your putting in the same bearings that just went bad- you aren't solving the issue.
        I'm not advocating the same bearings? VAC has coated aftermarket bearings.
      1. fundahl's Avatar
        fundahl -
        With VG30DETT platform the entire oiling system is reworked for higher volume. From the pickup tube to the oil pan to the ports. Then we can turn 9,000RPM and not run into issue. Assuming properly balanced rotating assembly and good crank damper.
      1. Nugs's Avatar
        Nugs -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I'm not advocating the same bearings? VAC has coated aftermarket bearings.
        Will this just make the clearance even tighter?
        Or does this not matter with the coating they use?
        @Mike@VAC
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Nugs Click here to enlarge
        Will this just make the clearance even tighter?
        Or does this not matter with the coating they use?
        @Mike@VAC
        @Mike@VAC is definitely the person to talk to regarding your questions about their bearings.
      1. AlexQuattro's Avatar
        AlexQuattro -
        Why is BMW having so much trouble with what everyone else seems to be getting right? I remember when the S1000RR came out, motors were seizing because of crank bearings.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Alex325i Click here to enlarge
        Why is BMW having so much trouble with what everyone else seems to be getting right? I remember when the S1000RR came out, motors were seizing because of crank bearings.
        It's their Achilles heel for some reason.
      1. vasillalov's Avatar
        vasillalov -
        So I wonder why we have not seen the same bearing failures in N54 engines. No dry sump, tuned engines have a lot more hp/liter and they go up to 7500 rpms easily. So what gives?
      1. Team Plutonium's Avatar
        Team Plutonium -
        Wait... so the problem is the oil pump, and the solutions are the coated bearings? How does that make any sense? Google "official S65 Bearing Specification/Clearance Wiki" (emphasis on clearance)... looks like the coated bearings will make the problem much worse.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by vasillalov Click here to enlarge
        So I wonder why we have not seen the same bearing failures in N54 engines. No dry sump, tuned engines have a lot more hp/liter and they go up to 7500 rpms easily. So what gives?
        Revs.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Team Plutonium Click here to enlarge
        Wait... so the problem is the oil pump, and the solutions are the coated bearings? How does that make any sense? Google "official S65 Bearing Specification/Clearance Wiki" (emphasis on clearance)... looks like the coated bearings will make the problem much worse.
        It depends on the application. On the S54 the problem was the actual bearing clearance as I recall and BMW replaced the bearings themselves. On the S65 the oil system and lubrication is part of the problem.
      1. Team Plutonium's Avatar
        Team Plutonium -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        It depends on the application. On the S54 the problem was the actual bearing clearance as I recall and BMW replaced the bearings themselves. On the S65 the oil system and lubrication is part of the problem.
        But that is not the main problem, the main issue is too little clearance, it simply needs more, and coated bearing will make it much worse.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Team Plutonium Click here to enlarge
        But that is not the main problem, the main issue is too little clearance, it simply needs more, and coated bearing will make it much worse.
        I wrote part of the problem.

        Regarding VAC's coating, it has been discussed what the coating adds to the bearings. @Mike@VAC
      1. alex@ABRhouston's Avatar
        alex@ABRhouston -
        custom coatings only add about 0.0003" of thickness- you cant hardly even measure that without precision equipment lol
      1. m54b25's Avatar
        m54b25 -
        Get some TriMetal rod bearings & right clearance to rebuild S60/S65 engine that can rev.9000rpm & don't increase stock NMAX (8250/8300). I.e bearings from: HK LMP2 V8 (from Engine Developments Ltd former JUDD Power engines.)

        http://www.engdev.com/products/hk-2011-lmp2-v8/