[R_S]

Hi guys!

I'm new here and coming up with a huge problem I struggle to explain.

Since I'm doing an LCI M-sport retrofit to my E90 and the front body panels are removed, I decided to tackle a few upgrade and maintenance jobs. Long story short, I did an oil pan gasket change.

Everything went well and the engine was set back together and ready to be started, BUT on the first start up, the engine started to knock what apparently sounded like a rod knock.

I'm puzzled and lost for words about how this could have happened because my car was running well before.

I made a video explaining this with some sound clips of the initial start on my YouTube channel.

Does anyone have any idea what could have gone so wrong to spin a bearing on the first start after doing such maintenance work?

Any comments and opinions appreciated!

[TheMidnightNarwhal]

My only "theory" or first thing I'd ask is if you did the oil priming procedure before starting the car after the work?

[R_S]

Originally Posted by TheMidnightNarwhal

My only "theory" or first thing I'd ask is if you did the oil priming procedure before starting the car after the work?

I'm going to be totally honest. Since the fuel rail was removed when doing VCG I thought that the engine would crank without a start for a few seconds while fuel pressure built up. So that is what actually happened. I cranked the engine for a solid 5-7 seconds before firing it up.

Could that not be enough to get the oil circulated and oil pressure built?

[Jacob97K]

Originally Posted by R_S

I'm going to be totally honest. Since the fuel rail was removed when doing VCG I thought that the engine would crank without a start for a few seconds while fuel pressure built up. So that is what actually happened. I cranked the engine for a solid 5-7 seconds before firing it up.

Could that not be enough to get the oil circulated and oil pressure built?

That is definitely to short in my opinion, after anything oil related in the car I always tend to prime the engine with 3-4 cranks of 10 sec with like a minute in between to let the starter cool down.

[feuer]

Just coincidental. Has nothing to due with oil pan job. Rod bearings can go at any point. Who told you that bearings aren’t common issue on n54 ? Definitely it is. If bearings aren’t replaced as preventative maintenance they will fail on all n54. At least car is disassembled so it will be easier to pull engine for rebuilding or swap.

[AWD Addict]

Hopefully the bearing didn't spin.

But I agree, this is likely a coincidence based on the work you did. Too bad too, because you were already under there! That would have been the time to do the bearings.

[R_S]

Hello people!

UPDATE: As I was sure that my rod bearings were toast, I again dropped the oil pan to inspect the bearings.

To my surprise, none of them had failed. They for sure don't look pretty and ask for immediate change but they couldn't be the reason for the engine knock.

My theory now is that the engine knock could come from a dry hydraulic lifter instead, but that really doesn't explain the metal shavings in the oil.

Any thoughts?

[335i54n]

cam ledge possibly for the metal or slight bent rod would be my guess. metal shaving or knocking imo is full rebuild, gl

[whyzee125]

Those bearings aren't spun but they are toast. If they went bad in a short amount of time, I'd be very suspicious of a bent rod. It's more common than you'd think.

[roadkillrob]

Those bearings look terrible, not worn through but they are not healthy.

[Jaronbwall]

Originally Posted by roadkillrob

Those bearings look terrible, not worn through but they are not healthy.

That's what I thought. No discoloring from high heat but too many scoring scratches. #3 specifically is worse.

[R_S]

Yeah, bearings are gone but they could not make the knocking sound.
As I inspected oil pump I found a piece of somekind of a wire. Now, looking up what it could be I figured out that it is a retainer wire / spring thing from a valve rocker like in this picture.

Could a rocker make a knocking sound when missing this piece?