Cold start rattle 2-3 seconds then gone.

[Slideways]

I will ask for pictures of the bolts. They did test the torque before they were removed, and confirmed that they were all still "torqued to spec"

Stock rod bolts don't work like that. The final torque is an angle torque in degrees (not ft-lbs). They might not be telling the whole truth here.

[Andratch]

What did the shop say and are there any pictures of the previous bolts? If they incorrectly torqued the rod bolts, you won't know if it was the bearings or the bolts that led to the bearing failure.

I will ask for pictures of the bolts. They did test the torque before they were removed, and confirmed that they were all still "torqued to spec"

[ac427]

Andratch
Great news. I hope this is definitely the cause of the rattle and the mystery is finally solved.

[Slideways]

"I suspect that the shop was not accustomed to using OEM bolts, and followed the ARP torque spec with OEM bolts, and the two are different."

What did the shop say and are there any pictures of the previous bolts? If they incorrectly torqued the rod bolts, you won't know if it was the bearings or the bolts that led to the bearing failure.

[Andratch]

!! BIG UPDATE !!

I THINK WE HAVE OUR CULPRIT! The noise definitely appears to be rod bearing / bolt related. So, good news on finding the cause, bad news that it isn't a cheap fix for others that might be experiencing it.


The BE bearings were trashed. Note that these had ~300 miles on them, they were installed in January of this year (2024). The stock rod bearings from 2005 looked way better than these. Very, very lucky that the crank was undamaged.

They were all installed and torqued properly, however this was part of the "bad batch" - and it shows.







New WPS bearings going in, and sending the BE's back for investigation.

[Giulianomitaly]

Hi friends, I'm Giuliano and I'm writing from Italy...I have the same noise on my S54 and my bearings are new ACL...does anyone have any news? Thank you

[eacmen]

Interesting, so to achieve the same result as the OEM bolt, they torqued the ARP bolts to 68 ft lbs, versus 50 ft lbs as specified in the ARP spec sheet for the M10s.

If I look at the instruction kit for the M11 vs M10, the M11 instructions pretty well match the stretch/torque that Lang did to achieve results on the M10 bolts.

I've asked the shop to use OEM bolts just for comfort, but for folks reading this thread in the future who want to use ARP, is the suggestion to stretch them to .0075? That's a little bit over-torque for the S50 spec but on the low end of the M11 S54 spec.

I wouldn't use one post from one engine builder as gospel for every engine. Lang has equipment to measure this stuff and get it perfect. Majority of bearing jobs are being done with the piston in the engine which don't give you the luxury of getting it perfect. Each rod is going to be slightly different and Lang is building engines to see continuous 8500rpm+ so their definition of acceptable is higher than most.

The safe option is obviously to just use the oem bolts.

Personally I opt'd for the ARP M10 bolts and torqued them with a stretch gauge to the ARP spec without issue for 12 track weekends thus far. I chose this option as the OEM bolts were on backorder at the time.

[Andratch]

Did you find that using Wayback Machine? I have referenced this post by Lang a few times, but couldn't find it when searching to quote it.

I found it reposted on m3cutters from 2016:

https://forums.m3cutters.co.uk/threads/oil-usage-and-rod-bearing-failure.166042/page-2#post-2184575

[Slideways]

Yes, but you are unfortunately at the mercy of the installer. If they follow the procedure outlined in BMW TIS, then it will be successful.



Exactly, with the rods out of the engine, the proper measurements can be performed, and if non satisfactory the rod can be resized (as ARP states is required for all their bolt offerings).

Some (seemingly lost) information from Lang on the subject:

I torqued the M11 stock bolts in a stock S54 rod with the 30nm > 70 deg angle and got a round bore within .0002". With oil the torque on the wrench read 68 ft/lbs.

I torqued the ARP 2000 M11 bolt in the same S54 rod gradually and measured the roundness of the bore. The bore got just as round as the stock bolt at .0068" of stretch. Spec is .0065" to .0070". This was 68 ft/lbs with the ARP lube. The ARP sheet says torque spec is 70ft/lbs.

I torqued the M10 stock bolts in a stock S54 rod with the 30nm > 105 degree torque and got round bores within .0002". This was between 62 and 66 ft lbs.

I torqued the ARP 2000 M10 bolts in the same rod and couldn't get the bore round until I stretched them .0075". This torque was about 68 ft/lbs. The ARP spec sheet says to torque these to 50 ft/lbs and .0065" to .0070".

Did you find that using Wayback Machine? I have referenced this post by Lang a few times, but couldn't find it when searching to quote it.

[Andratch]

I torqued the M10 stock bolts in a stock S54 rod with the 30nm > 105 degree torque and got round bores within .0002". This was between 62 and 66 ft lbs.

I torqued the ARP 2000 M10 bolts in the same rod and couldn't get the bore round until I stretched them .0075". This torque was about 68 ft/lbs. The ARP spec sheet says to torque these to 50 ft/lbs and .0065" to .0070".[/I]

Interesting, so to achieve the same result as the OEM bolt, they torqued the ARP bolts to 68 ft lbs, versus 50 ft lbs as specified in the ARP spec sheet for the M10s.

If I look at the instruction kit for the M11 vs M10, the M11 instructions pretty well match the stretch/torque that Lang did to achieve results on the M10 bolts.

I've asked the shop to use OEM bolts just for comfort, but for folks reading this thread in the future who want to use ARP, is the suggestion to stretch them to .0075? That's a little bit over-torque for the S50 spec but on the low end of the M11 S54 spec.

[bmwfnatic]

So, is the consensus that for '05-'06 models, the ONLY bolts that will work without risk are the OEM?

Yes, but you are unfortunately at the mercy of the installer. If they follow the procedure outlined in BMW TIS, then it will be successful.

Unsolicited opinion incoming, but I would personally stick to the OE bolts. I wouldn't trust anyone who tells you that the S50 bolts work on the S54 unless they have documentation of installing them on a rod (that's out of the engine) and measuring the roundness of the bore.

Exactly, with the rods out of the engine, the proper measurements can be performed, and if non satisfactory the rod can be resized (as ARP states is required for all their bolt offerings).

Some (seemingly lost) information from Lang on the subject:

I torqued the M11 stock bolts in a stock S54 rod with the 30nm > 70 deg angle and got a round bore within .0002". With oil the torque on the wrench read 68 ft/lbs.

I torqued the ARP 2000 M11 bolt in the same S54 rod gradually and measured the roundness of the bore. The bore got just as round as the stock bolt at .0068" of stretch. Spec is .0065" to .0070". This was 68 ft/lbs with the ARP lube. The ARP sheet says torque spec is 70ft/lbs.

I torqued the M10 stock bolts in a stock S54 rod with the 30nm > 105 degree torque and got round bores within .0002". This was between 62 and 66 ft lbs.

I torqued the ARP 2000 M10 bolts in the same rod and couldn't get the bore round until I stretched them .0075". This torque was about 68 ft/lbs. The ARP spec sheet says to torque these to 50 ft/lbs and .0065" to .0070".

[heinzboehmer]

Unsolicited opinion incoming, but I would personally stick to the OE bolts. I wouldn't trust anyone who tells you that the S50 bolts work on the S54 unless they have documentation of installing them on a rod (that's out of the engine) and measuring the roundness of the bore.

The torque sequence for the OE bolts is tedious, but not exactly hard. Any decent mechanic should be able to follow the sequence without issue...

[Andratch]

If you use ARP, you need to make sure they torque to yield spec, not just torque, as indicated, the M10 bolts are for the S50 engine, and one could argue they are similar enough on the bottom end design that the S50 bolts can be used on the S54, but you need to torque the bolt to it's stretch spec, not just the generic torque. All this tells me the shop does not know what they are doing, walk away!

I remember remember them mentioning yield spec unprompted last week, but i'll be sure that's what they do. I am not certain that the fault is on the shop, especially given that the particular batch of BE bearings is now known to be faulty. I'm getting an 'upgrade' of sorts out of it, so for now I'm okay. We'll see what things look like when the pan comes off.

[maupineda]

If you use ARP, you need to make sure they torque to yield spec, not just torque, as indicated, the M10 bolts are for the S50 engine, and one could argue they are similar enough on the bottom end design that the S50 bolts can be used on the S54, but you need to torque the bolt to it's stretch spec, not just the generic torque. All this tells me the shop does not know what they are doing, walk away!

[Andratch]

You can use ARP bolts for the M11 early engines up to 12/2002 based on your pictures you have an 05 or 06, which has the M10 bolts. ARP doesn’t sell bolts for those, period.

They do for the Euro S50, which some vendors like Bimmerworld stupidly market as being made for the S54, but there is no such mention on the ARP website.

It has been documented on this forum and elsewhere that using the S50 ARP bolts in S54 rods makes them out of round, which will certainly accelerate your rod bearing wear. Use Genuine…

So, is the consensus that for '05-'06 models, the ONLY bolts that will work without risk are the OEM?