[kevinb21]

I have a 2011 bmw 335i coupe, got it with around 111,000 miles on it and very quickly discovered it had a mild rodknock. It was quite mild, but it was clear that it was time to replace the engine. I found a clean n55 from a dismantler that had great compression numbers and purchased it. Before installing it in the car I had all the gaskets replaced along with the rod bearings, the new bearings were king rod bearings, they all had assembly lube placed on them before install and everything was done with oe bolts and torqued properly. The car ran great and still runs great and makes good power on a tune, although only on cold starts, it just does not sound smooth, it almost sounds like there is a really really mild metallic knock or noise when the engine is cold, Right around 1,000 mile mark on the new engine I did an oil change, there was not a severe level of metal shavings or anything beyond what I would expect for a fresh engine.

I recorded a video of how the car sounds right when it is cold after replacing the oil and linked it here, the car only sounds this way when it is cold, when the engine is warmed up it runs buttery smooth and does not make this much noise at all.

Could this be my rod bearings? already? again? after only 2,000 miles? and no I never beat on my car cold, I do drive short trips due to everything being close.

[fastboatster]

did you check the bearing clearances or just installed the new bearing shells? did you prime the oil system?

[kevinb21]

Originally Posted by fastboatster

did you check the bearing clearances or just installed the new bearing shells? did you prime the oil system?

Yes bearing was the Standard size and everything was checked before install, I did crank the car a good amount before actually starting the engine to build oil pressure, I have used KING std rod bearings on 3+ bmws now, hoping this isnt an issue, does the video sound like early rod knock? the car makes no noises at all warm, just this minor sound when ice cold

[fastboatster]

Originally Posted by kevinb21

Yes bearing was the Standard size and everything was checked before install, I did crank the car a good amount before actually starting the engine to build oil pressure, I have used KING std rod bearings on 3+ bmws now, hoping this isnt an issue, does the video sound like early rod knock? the car makes no noises at all warm, just this minor sound when ice cold

Hard to tell, I'd put it on ramps and try to see if this noise is coming from the oil pan. Maybe even pull the pan out and check the rods

[Grease23]

In my experience, bearing issues are more of a loud, deep thudding sound.

Mild piston slap, perhaps? That going away completely when warn is a classic symptom.

[kevinb21]

Yeah in the past I have had issues with spun rod bearings on other cars, that is actually how this car's previous engine went.... this motor only has around a thousand miles on it and its new bearings. My assumption was that this might be a really early sign of the bearings going out, not entirely sure. it does not knock at all under load or while driving it hard, then it sounds perfectly fine, when the oil is warm there is no knock at all, the sound is entirely dependent on oil temp, colder the oil, the more I can notice it.


Really hoping the engine isnt about to go.

Originally Posted by Grease23

In my experience, bearing issues are more of a loud, deep thudding sound.

Mild piston slap, perhaps? That going away completely when warn is a classic symptom.

[kevinb21]

Originally Posted by fastboatster

Hard to tell, I'd put it on ramps and try to see if this noise is coming from the oil pan. Maybe even pull the pan out and check the rods

The noise is most pronounced when you put your ears against the wheel are while the car is running, thats where I hear it the most, it does not really come from the oil pan itself or below the car. I have placed a stethescope on various parts of the motor while idling and I hear nothing out of the ordinary, just rotational consistent noise along with injector tick when I place them in that area.

The bearings and oil pan were off before this new motor was installed 1k miles ago, the old bearings were honestly in amazing condition, even so were replaced with these new ones for piece of mind. when the oil is hot there is zero noise car runs awesome. is the noise out of the ordinary? if it sounds like a rod bearing that is on its way out I figure my best chance is to take it apart and inspect the crank before I cause real damage. Im just hoping that is not the case.

[kevinb21]

Originally Posted by kevinb21

The noise is most pronounced when you put your ears against the wheel are while the car is running, thats where I hear it the most, it does not really come from the oil pan itself or below the car. I have placed a stethescope on various parts of the motor while idling and I hear nothing out of the ordinary, just rotational consistent noise along with injector tick when I place them in that area.

The bearings and oil pan were off before this new motor was installed 1k miles ago, the old bearings were honestly in amazing condition, even so were replaced with these new ones for piece of mind. when the oil is hot there is zero noise car runs awesome. is the noise out of the ordinary? if it sounds like a rod bearing that is on its way out I figure my best chance is to take it apart and inspect the crank before I cause real damage. Im just hoping that is not the case.

bummpp

[sowbmw]

Any update on the sounds?