Big End Gone

[Geddin]

Yeah that’s my point. At idle I’d have expected it to be nosier with big end issues. Not an expert but that’s from experience.

I’ve noticed these engines are naturally quite ‘tappy’ at idle with the bonnet up

To me the noise is more is a rattle. Like something is loose, and getting worse when the revs increase. Like one of the ancillarys

In probably over stepping my mark there though. I’d ask someone with more experience

 

[Smallsy99]

Thank you! Yeah it’s really hard to know. The one thing is that there are copper filings in the oil filter. This apparently is a big red flag as copper is only in one location - the sleeves on the big end. So it’s gotten hot and rubbed this sending bits around

 

[Geddin]

Have you had the oil tested? Or is that just visible filings?

 

[Smallsy99]

It’s apparently just visible filings - I haven’t seen them myself. Just reporting back what I’ve been told

 

[Geddin]

Hope this helps....

For a N52 engine, the most common causes for a rattling sound when revved, along with metal filings in the oil, are likely related to one of the following issues:

1. Rod Bearing Wear: (what the garage thinks)
- The N52 engine, while generally reliable, is known to develop rod bearing issues, especially as it ages or if it has been driven hard. The symptoms of rod bearing wear include a rattling or knocking noise, particularly under load or when revving the engine, and metal filings in the oil are a common sign of bearing material wearing away.
- Why It's Common: Rod bearings are under significant stress, and if the engine has experienced low oil levels, oil starvation, or simply high mileage, these bearings can wear out.

2. Timing Chain and Tensioner Issues:
- Common in N52: The N52 engine has a timing chain that, over time, can stretch or the tensioner can wear out, causing a rattling noise, especially at higher RPMs. While metal filings from the timing chain are less common, they can occur if the chain is wearing against other metal components.
- Noise Source: A worn timing chain or tensioner typically produces a rattling sound at the front of the engine, more noticeable when the engine is under load.

3. Hydraulic Lifters (HVA) or Valve Train Wear:
- Valve Train Issues: The N52 engine has been known to develop issues with hydraulic valve adjusters (HVAs), which can create a ticking or rattling noise. However, significant valve train wear could also lead to metal filings in the oil if components such as camshaft lobes or rocker arms start to wear out.
- Why It's Common: This issue is less common but still possible, especially in engines with higher mileage or inadequate oil changes.

4. Piston Slap:
- Piston slap can occur if the engine has experienced excessive wear or poor maintenance. This would cause a rattling noise that gets louder as the engine is revved. The N52 is an aluminium block engine with cast iron sleeves, and while not prone to this issue, it can happen under certain conditions.
- Metal Filings Source: The metal filings in the oil could come from excessive piston or cylinder wall wear.


Next Steps:
- Oil Analysis: Performing an oil analysis or inspecting the oil filter for metal debris can help confirm the source of the metal filings.

 

[Ed Doe]

The cylinder liners are made of Alusil.

How will inspecting the oil filter help identify the cause of the filings?

How are HVAs going to cause that noise?

Have you heard what a slack timing chain sounds like? It's a 'shhhick shhhick' noise, like something rubbing, not a clatter like that.



From that video, and based on finding a load of copper in your oil, the changes of it being anything other than rod bearings is pretty remote; there isn't anything else copper in the rotating assembly apart form the rod bearings, and certainly nothing that will cause that sort of noise when revved up.

 

[Geddin]

I’m not saying it is any of those other things, but it’s possible. What it recommended was an oil analysis to check what the metal is.

 

[Smallsy99]

Hope this helps....

For a N52 engine, the most common causes for a rattling sound when revved, along with metal filings in the oil, are likely related to one of the following issues:

1. Rod Bearing Wear: (what the garage thinks)
- The N52 engine, while generally reliable, is known to develop rod bearing issues, especially as it ages or if it has been driven hard. The symptoms of rod bearing wear include a rattling or knocking noise, particularly under load or when revving the engine, and metal filings in the oil are a common sign of bearing material wearing away.
- Why It's Common: Rod bearings are under significant stress, and if the engine has experienced low oil levels, oil starvation, or simply high mileage, these bearings can wear out.

2. Timing Chain and Tensioner Issues:
- Common in N52: The N52 engine has a timing chain that, over time, can stretch or the tensioner can wear out, causing a rattling noise, especially at higher RPMs. While metal filings from the timing chain are less common, they can occur if the chain is wearing against other metal components.
- Noise Source: A worn timing chain or tensioner typically produces a rattling sound at the front of the engine, more noticeable when the engine is under load.

3. Hydraulic Lifters (HVA) or Valve Train Wear:
- Valve Train Issues: The N52 engine has been known to develop issues with hydraulic valve adjusters (HVAs), which can create a ticking or rattling noise. However, significant valve train wear could also lead to metal filings in the oil if components such as camshaft lobes or rocker arms start to wear out.
- Why It's Common: This issue is less common but still possible, especially in engines with higher mileage or inadequate oil changes.

4. Piston Slap:
- Piston slap can occur if the engine has experienced excessive wear or poor maintenance. This would cause a rattling noise that gets louder as the engine is revved. The N52 is an aluminium block engine with cast iron sleeves, and while not prone to this issue, it can happen under certain conditions.
- Metal Filings Source: The metal filings in the oil could come from excessive piston or cylinder wall wear.


Next Steps:
- Oil Analysis: Performing an oil analysis or inspecting the oil filter for metal debris can help confirm the source of the metal filings.

That’s amazing thank you! I’m going to try and take it to another garage for a second opinion. Go from there!
There are just seemingly too many unknowns. The garage it is at hasn’t taken anything apart just the oil filter I believe

 

[CliveN]

Get a second opinion. Long shot but my NSX developed an awful knocking noise from idle upwards. All thought it was the big ends as the noise was from the bottom of the motor. It turned out to be a failed air compressor pulley bearing.

 

[Mr Tidy]

That’s amazing thank you! I’m going to try and take it to another garage for a second opinion. Go from there!
There are just seemingly too many unknowns. The garage it is at hasn’t taken anything apart just the oil filter I believe

I'm a bit late to this but I'd recommend getting the 2nd opinion from a good BMW Indy.

I haven't read about big end bearing failure on an N52 engine before - and my 330i just went past 126K today!

 

[Smallsy99]

Yeah I’m taking it to a second garage next week. I won’t say what I’ve been told just see what they think! I know I thought these engines were pretty bomb proof.
I’m not sure about going through a fair chunk of oil is normal though. Drove to Le Mans - flagged up oil there. Couldn’t immediately stop so drove about 40miles ish, added 500ml.
Then end of July it said I needed 1L that’s when the problems occurred

 

[Rockhopper]

At this point though it doesn't really matter what's gone wrong - you've got a filter full of metal - the only decision to make is what you do about it. Sell it on, rebuild it or swap the engine.

 

[Smallsy99]

I’m leaning towards getting it rebuilt, there is a place in Peterborough that does it well

 

[Stash36]

I guess this is why you havent been in touch about my rear light!
Sorry to hear the problems, hope you get it sorted without too much expense.