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M54B30 Con Rod Cap Torque procedure

24K views 6 replies 2 participants last post by  white_335i  
#1 ·
TIS tells me 5nm assembly, 20nm initial then 70 degrees… Can anyone confirm if I do this 3 times, like the newer S54 motors, or just once. It looks like just once per TIS, but the bolts have the same torx heads and appear to look just like the S54 con rod cap bolts that require the 3 step process.

TIA

BTW: I've read and seen posts in several places about the M54B30s having fracture split rods. Mine are not. What's the deal? Build date is 02/2003. As far as I can tell no one has been in here before me.
 
#4 ·
OK... so I've compared the con rod bolt PNs on RealOEM between the S54 and M54s and although the 2 fasteners look alike and have the same torx head type, they are in fact different PNs and different spec (IE: M10X1,25 vs M9X47MM) Trolling through TIS confirms the S54 bolts are indeed to be torgued no less than 3X and no more than 5X. Presumably max clamping force is reached between 3rd & 5th stretch with those bolts. The M54 instructions and torque specs in TIS make no reference to needing to be stretched like this so I'm going to assume it's correct and will go for a once & done approach as I torque them.

I still haven't figured out which M54B30s got fracture split rods, if any. If anyone here has done rod bearings in their 330 and can tell me what their end caps looked like, and their build date, I'd appreciate it.
 
#5 ·
Hi 325ragtop, I just finished replacing the rod bearings on my 330I. I went to the dealer to get torque specs and the dealer pulled the torque values from All data. All data says to torque 5nm,30nm and 70 degrees. I see that you used 20nm.. Did you run in to any issues with using 20nm? I am thinking that I should order new bolts now and torque them to the specs you listed. Please advice.

Thanks,
 
#6 ·
Hey white_335i, sorry for the delayed response...haven't been on here in about a month. Too much"life" happening! :) I did the 5, 20 then 70deg as per TIS, just one time, and have subjected the motor to about 10-12 track days of punishment and not had any issues. You've probably already decided what to do by now, but if it were me, I would trust what the dealer told you. It's surprising to hear you say a BMW dealer used All-Data for their reference. I'm sure they must have the TIS software directly from BMW. Perhaps they just referred to it as "All-Data" in a generic sense. My copy of the software is about 6-7 years old so possible they revised the spec.

BTW - What do your connecting rods look like? I've seen photos on the web of split fractured rod caps claiming to be from M54s but haven't seen any 1st hand.
 
#7 ·
Thanks for getting back. The dealer gave me hard copies and they say all data. Not sure why he did not refer to TIS. Oh well, I got it done. I had a hard time doing the 70 degree angle. What I did was, torque all the bolts to 5nm then 20nm. Then I torqued one bolt to 70 degrees and took my torque wrench and measured the torque. It came out to roughly 60nm. I set my torque wrench to 60nm and tightened all the bolts. I have a digital angle torque wrench and even for a slight variation, it jumped all over the place. Right or wrong, that is how I did mine and so far no issues. I guess time will tell.

Connecting rods looked like split fractured to me.