Friday, January 7, 2011

Mix and Match ordeal

So everything was coming along together nicely after the last post. The next step was to replace the rod bearings. Everything was still going along very nicely. As pictured, an engine support held the engine up while I dropped the front subframe for access to the oil pan. Once removed, I started to remove the rod bolts. Thinking I was just getting new ones, I did not bother to mark them (more on that later). With new parts in hand, I replaced one of the rod bearings (dont remember if it was #3 or #4 now) and they looked fairly worn. Upon reassembly, the new rod bolts did not fit!!!! The new bolts were M10 which are the updated BMW rod bolts for the connecting rods after the whole recall debacle. Mine were M11, which was odd.

BMW stopped making engines with the M11 somewhere in late 2002 and this car being a 2004, that was SUPER odd. Some further research on a serial # sticker on the side of the block led me to some deciphering PDF designating this motor as a BMW Reman. built in 2002. So at some point in this car's prior life, someone blew the motor and put in a replacement. All done outside of BMW since there is no service history to this. Even more perplexing is the previous owner bought the car around 50k miles which would make it even more odd that the owner before him would have done something outside of warranty. Anyhow, it is what it is.

Now that I know my car has the older M11 bolts, the BMW recall procedure says you can reuse the rod bolts ONLY if you mark them and put them back in their original rod bolt locations. WHOOPS! What now? BMW doesnt make the M11 bolts anymore. So I ended up having to procure some ARP Rod Bolts from our friends at VAC Motorsports in Philly.

The rod bolts have been reinstalled and Im glad I took the opportunity to inspect and replace the rod bearings. See picture for crazy wear, especially on the #2 cylinder (top row, 2nd pair in picture). The connecting rod ride of #2 rod bearing even had a little copper showing, which means it was almost worn through!

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