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Discussion Starter · #1 ·
Once again my little 125i is causing me grief.

It's leaking oil in a way that causes enough smoke/smell to be noticable and unpleasant when stopped at traffic lights.

This area around the filler cap was completely clean recently and now it is not. I did an oil change a few weeks ago and cleaned up after myself.
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This cap is very new, the valve cover is very new, albeit not a genuine BMW... I would a assume this is likely to be pcv related? Is it possible that the pipe that runs from the back of the cover to a couple other spots is that blocked up? I didn't replace it when I change the cover, which is dumb as hell seeing as I have one sat in my parts drawer.

Any suggestions?

The cause of my smoking may not be this leak, but it's the most obvious currently.
 

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Discussion Starter · #3 ·
That's not a genuine BMW filler cap, so that would be my first port of call!

PCV is built into the valve cover on the N52K. If you've swapped yours recently, it should be working fine.
I actually is genuine! From my local dealer, so I'd hope its real aha.

PCV is in the cover, you're right. I explained it badly. What I actually mean is crank case breather hose/pipe. Like this image, although my new one is from Gates.

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I'm about I managed to get 2 of the 3 ******* clip things undone. But sadly the middle one under the intake manifold isn't budging. I need to remove the whole intake manifold I think now :(
 

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Discussion Starter · #5 ·
Mines square. Sure they haven't given you a Mini one by mistake?
Is yours still original?

The originals are square yes, I needed a replacement about a year ago because it was clearly pissing out the cap when running. This is the new part no as per RealOEM

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Discussion Starter · #8 ·
Ooh I stand corrected in that case!

Is the gasket underneath the cap in good nick? I replaced mine not long ago after noticing seepage.
Yes the gasket underneath is new as well. :)

Me too ☝
As far as I know it is but didn't know it had been superseded.
Neither did I until I wanted one aha. I prefer the square looking ones for sure!!

Right pain in the ass to figure out what the problem is.

If replacing the pipe doesn't solve it, anyone got suggestions?
 

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get the oil pleasure measured, has the relief valve stuck open, id expect a code have you checked for codes ? What's the air filter/inlet system like ? any blockages ?
 

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Discussion Starter · #10 ·
get the oil pleasure measured, has the relief valve stuck open, id expect a code have you checked for codes ? What's the air filter/inlet system like ? any blockages ?
How would I go about measuring oil pressure? And again forgive my ignorance, which relief valve? I have absolutely no codes at all!

I honestly haven't managed to get a good look at the whole intake system, I started trying to get CCV hose off about 8:30pm and ran outa light. So will have another go saturday evening/sunday/
 

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Discussion Starter · #12 ·
You'll need some kit.........
Why did they use a car from 1864 :ROFLMAO:

OK well, once i get my CCV pipe/hose off and inspect the rest of the intake system. I will hopefully find a blockage. I shall remove/sort blockage and reassemble. Hoping that it solves the issue, if it doesn't I'll be borrowing an oil pressure tester from somewhere!
 

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it's genuine, when I had mine replaced for same reason, I got the self same cap

That's not a genuine BMW filler cap, so that would be my first port of call!

PCV is built into the valve cover on the N52K. If you've swapped yours recently, it should be working fine.
 
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The oil pump relief valve it stops the pump over pressuring the system, you might be able to check the oil pressure
via the OBD socket.
 

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Discussion Starter · #15 · (Edited)
I'm getting more stuff torn down at the moment, just got the throttle body off. Oil on the inside of that, normal? Or something to be concerned about?

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Additional concern, should there be a vacuum line on pcv unit?

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Discussion Starter · #17 ·
Arse. All of this was a waste of time, the ccv hose was totally intact and seems to have same airflow as the new one.

No idea what else could be happening here. I guess I can try another new oil filler cap?!
 

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Air filter ok ?
 

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Discussion Starter · #20 ·
Air filter ok ?
Yeah it's the BMW Performance/K&N one but dry. That said it was on the car before I got it 2 years ago. So god knows how old it is.

If you pop the engine cover off does it look like it's definitely the filler cap that's the leak point?
No it doesn't. Not for sure. I think my next step will be to change the valvetronic gasket. Because its pooling under there and that could either run down from the filler cap.. Or the gasket itself is ****.

Which would be annoying because its a new gasket it on a new cover. But I already have a spare one so nothing more than time needed.

I did a bit of Googling and this seems like a relatively common issue on the N52!
 
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