[340idude]

Curious if f30's have been having rod bearing issues on the n55? Does a n55 have a normal faint knocking sound near 1900rpm - 2500rpm?

[cfm56d7b]

Originally Posted by YoyoF30

Curious if f30's have been having rod bearing issues on the n55? Does a n55 have a normal faint knocking sound near 1900rpm - 2500rpm?

The short answer is unfortunately yes. There are many threads on this very issue which affected a small percentage of N55 engines in 2013 model year (the cases I am personally familiar with).

The symptom is a faint "clickity clack" sound at idle speeds.

Oil analysis will reveal excessive metal shavings.

[340idude]

Hmm the reason I ask is because ive test driven a 2015 and 2014 n55 based engine (both good service, low miles around 40-50k). They both produced a little knocking like noise at the above rpm :/. So debating if its normal or not (since both were faint, but defs a little knock).

[Polo08816]

Originally Posted by YoyoF30

Hmm the reason I ask is because ive test driven a 2015 and 2014 n55 based engine (both good service, low miles around 40-50k). They both produced a little knocking like noise at the above rpm :/. So debating if its normal or not (since both were faint, but defs a little knock).

It's normal for idling. It's direct injection.

[340idude]

Direct injection would be a ticking near the top of the engine... I heard the faint knocking on both near the bottom (can hear it on the inside, or when the hood is open towards the passenger side)

[k3vin0615]

rod knock would sound like a machine gun.

[XutvJet]

^Yep, that's what rod knock sounds like. Rarely do you hear it at idle. It's typically heard between 1,500-2,500 rpms on most cars.

The 2014+ N55s don't seem to have much issue as the rod bearings were improved in the 2013. The 2014+ N55s use the same rods and rod bearings as the M2C/M3/M4 S55 motor.

[340idude]

Its was a 2015 Model year (built in late 2014) car with 39k miles, service history showed oil changes every 6-8k miles. during ppi oil filter had metal shavings. So the problem exists beyond 2013 model year unfortunately.

[XutvJet]

A ppi inspection did an oil change?

Regardless, rod bearing failures in the 2014+ models is rare.

[340idude]

Lol, I pushed them for a oil filter inspection (they kept saying the sound is normal, asked them to let me see the oil filter and if it came clean ill buy it. But sure enough, filter was full of silver flakes). This was at a BMW dealer aswell, which presumably went through CPO inspection blah blah. The dealer admitted the flakes arent normal and will be pressing for an engine replacement by BMWNA before its sold. The 2014 car was a private dealer but did have the same kurr kurr(knocking as the video above but faint) sound when reving from 1500 up to 2k-2.5k.

But yes, it might be RARE but not impossible (just trying to keep potential buyers aware to check oil filter if youre suspicious). The cars had good service records but no one can say if the previous owners modded them or drove them like sh*t.

Will now be looking into b58 instead (for the price difference rather have something with longer warranty)