[Psalm_Kuru]

Hi everyone.
I have only recently purchased this 2009 335D E91, has currently nearly 125,000miles. I have purchased only parts that look like theyre leaking which I haven't installed,
Intake Manifold Gasket set.
Red Boost Pipe Seals (was unable to get it release from intercooler)

Oil Pan Gasket to me looks good from all corners except the intake side,
The valve cover gasket looks dry on all the corners.
Just today, I am nearing my first 6,000 miles. I have undone the engine splash shield multipled times and may have removed that matt like plastic on it, over this period since temoving it I haven't had visible leaking on my driveway but underneath has become covered in oil, reaching near the rear differental, when I first purchased it and done the oil change nearly straight afternoon there was minimal signs of oil leakage.
Its kind of starts near the dipstick tube, intake manifold, but also around where the engine/transmission meet, whats the possibility of the rear main seal leaking? Which is time consuming and potentially very expensive. Isn't something I want to pursue. I did wipe it all down tonight slightly degreased it, and after a quick 15 minute drive oil began to leak around the engine/transmission area again?
What is your experience/thoughts?
Please let me know, I will degrease, and change the intake manifold seals next week when I get a torque wrench, and see how it goes.
Does anyone happen to know the o ring size for the oil dipstick tube,
And potentially the blanking plate o ring size for the Swirl flaps blanks not sure if those are leaking?

Notes: my vehicle is a RH Hand drive, so everything is on the opposite side I believe, no turbo feed lines are leaking from what I have seen just to add to this note

[GSB]

I have an N54 335i (petrol). My rear main seal leaks badly if the PCV valve is malfunctioning. Pressure builds up in the crankcase and pops the seal. I'm not sure how the PCV system works on the diesel, but check it! The boost side PCV system has a flapper that seldom fails, but the non-boost side has a notoriously bad PCV valve built into the valve cover.

The oil pan gasket is notorious for leaking on this engine too.

[NZE90]

That oil leak looks too clean for diesel oil. Usually the engine oil has a black tinge in a diesel. Could it possibly be a trans oil leak?

Also, with the intake manifold leak, it's usually the swirl flap shafts that leak, not the gaskets.

[Psalm_Kuru]

Originally Posted by GSB

I have an N54 335i (petrol). My rear main seal leaks badly if the PCV valve is malfunctioning. Pressure builds up in the crankcase and pops the seal. I'm not sure how the PCV system works on the diesel, but check it! The boost side PCV system has a flapper that seldom fails, but the non-boost side has a notoriously bad PCV valve built into the valve cover.

The oil pan gasket is notorious for leaking on this engine too.

Thanks for the quick reply, and sorry about the late one 🤦🏽
Yeah I have a few questions about my PCV to be honest. I have resolved majority of the oil leak I believe I will note town below once I reply NZE90. But as for the PCV when I remove the oil filler Cap at idle, it seems to have no pressure or vaccum, apparently you should have slight vacuum, I looked at the pcv yesterday and it looked new, if I get it just a tiny bit of rpm then itll start having a slight vacuum. But at idle it seems neutral.
Does this sound right to you?

[Psalm_Kuru]

Originally Posted by NZE90

That oil leak looks too clean for diesel oil. Usually the engine oil has a black tinge in a diesel. Could it possibly be a trans oil leak?

Also, with the intake manifold leak, it's usually the swirl flap shafts that leak, not the gaskets.

Yeah I think maybe the flashlight/camera just made it look cleaner than it was, and it was only a thin film so probably not so black being thin, I replaced the intake manifold gaskets, seals further to the rear were extremely hard, and covered in oil and signs of leakage, but the intakes looked absolutely spotless internally! and I aint even over exaggerating, I already have the swirl flaps blanked but just replaced the o'rings on those blanking plates anyway to prevent going back again... as for the transmission, and thanks for your other reply. I will get onto servicing it just for precaution... I have done about 300kms since the works been done and no signs of any oil where it was accumulated, just seemed weird it made its was down to the rear centre of the engine/transmission.

[GSB]

Originally Posted by Psalm_Kuru

Thanks for the quick reply, and sorry about the late one 🤦🏽
Yeah I have a few questions about my PCV to be honest. I have resolved majority of the oil leak I believe I will note town below once I reply NZE90. But as for the PCV when I remove the oil filler Cap at idle, it seems to have no pressure or vaccum, apparently you should have slight vacuum, I looked at the pcv yesterday and it looked new, if I get it just a tiny bit of rpm then itll start having a slight vacuum. But at idle it seems neutral.
Does this sound right to you?

I'm not familiar with the diesel PCV system, but I would expect to feel some vacuum at the filler cap during idle.

[GSB]

Originally Posted by Psalm_Kuru

I replaced the intake manifold gaskets, seals further to the rear were extremely hard, and covered in oil and signs of leakage, but the intakes looked absolutely spotless internally!

This seems a little puzzling... When you say the intakes were spotless, do you mean the intake ports and valves in the head? Any oil in the intake system is usually sucked all the way into the ports and valves.

[Psalm_Kuru]

Originally Posted by GSB

I'm not familiar with the diesel PCV system, but I would expect to feel some vacuum at the filler cap during idle.

Yeah my thoughts exactly might buy a new one then.
But doesn't seem to be giving any issues thus far.

[Psalm_Kuru]

Originally Posted by GSB

This seems a little puzzling... When you say the intakes were spotless, do you mean the intake ports and valves in the head? Any oil in the intake system is usually sucked all the way into the ports and valves.

Sorry mb, wrong choice of words. Yeah intake ports/valves were absolutely spotless!
I was quite shocked personally considering how much oil was leaking from the intake

[GSB]

Originally Posted by Psalm_Kuru

Sorry mb, wrong choice of words. Yeah intake ports/valves were absolutely spotless!
I was quite shocked personally considering how much oil was leaking from the intake

Well, that's pretty fortunate that the valves are so clean, but oil leaking from the intake is concerning. It probably just means that PCV oil is not making it to the valves due to air leaks in the dried-up rubber gaskets, and instead, that oil slides down the intake and out of those gaskets as soon as the engine is shut off.