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[bigjae46]

I’d double check. That check valve is there to prevent oil back feeding into the intake which would result in an excessive amount of oil in the intake. Similar to the problem you’re having. BMW put a check valve on the plastic line for a reason.

I think to assume an engine builder and machine shop are infallible is a poor assumption.

Really can’t blame the airbox. Oil is escaping into the intake because something was installed incorrectly or a part is missing.


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[mainstreamer00]

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[natty99]

I’d double check. That check valve is there to prevent oil back feeding into the intake which would result in an excessive amount of oil in the intake. Similar to the problem you’re having. BMW put a check valve on the plastic line for a reason.

I think to assume an engine builder and machine shop are infallible is a poor assumption.

Really can’t blame the airbox. Oil is escaping into the intake because something was installed incorrectly or a part is missing.


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Are you referring to part #3 here:
https://www.realoem.com/bmw/enUS/sho...diagId=11_3797


Another link:
https://www.ecstuning.com/b-genuine-...e/11617831930/

[terra]

If you're using that hose with solenoid with the CSL software, that might be the problem. That solenoid is open when not energized, and the CSL software doesn't have any provision to control that valve. So theoretically it's open to vacuum, which creates a venturi effect across the PCV and pulls oil into the intake.

[jbfrancis3]

I don’t disagree with you at all.

Question - I haven’t explored a diagram yet (and this process happened while I wasn’t there), but are there are substantial differences between an evolve and Karb box from a venting/connections perspective?

Why are you asking this now? You’ve already implied there is by titling the thread Karb/[aftermarket] air box leads to engine failure. Should you amend the way the question is being asked?

[bigjae46]

Are you referring to part #3 here:
https://www.realoem.com/bmw/enUS/sho...diagId=11_3797


Another link:
https://www.ecstuning.com/b-genuine-...e/11617831930/

Yes. There is a check valve built into the drain line.

If that ends up being the case, I’d really question whoever installed the engine. How do you blame an airbox for drawing oil into itself?

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[sc_tr0jan_m3]

i can't say i've had issues with my karbonius unit. it was installed by the previous owner with a radium catch can before i took over the car 2 years ago. it's been nothing but solid with about 20k track miles. the catch can does work and picks up fluids, but i can't say i've noticed anything negative about performance or something that'd indicate engine failure.

[mainstreamer00]

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[sapote]

Since no oil should be collected in the airbox with a working catch can, try this simple test: remove the #3 hose between the airbox bottom and the dip tube, and plug up the 2 opening holes. Run the test again.

[Slideways]

OP, did they pinpoint exactly where the oil is coming from? Really, there is only two places on the intake: the crankcase vent hose and the oil return line to the oil pan from the airbox. How full is the catchcan? Do you have a picture of the airbox internals before any cleaning?

[mainstreamer00]

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[Slideways]

Taken from the recent report:

22. 17/03/21 leak down after 100km 5% on all 6 cylinders. Found engine oil in all cylinders upon inspection. Checked airbox found oil in bottom of the box. Checked catch can for oil residue. Found 1” of volume on the dip stick. Removed breather hose to top of air box and found more oil residue indicating its ingesting through the breather system. Cleaned out the cylinders and airbox of excess oil. We suspect the oil is coming from the breather system. To verify we removed the breather hose from the airbox and wrapped the openings in a breathable cloth. The idea is to remove the vacuum source at the air box from the breather system. The car was then driven 80 more kms. The oil injestion has stopped. The airbox and cylinders are clear of any oil resdue. The engine is still on Total Quartz 5000 to complete break in. We will switch to LubromolySynthoil Race Tech GT1 SAE 10w60 after 300kms.



23. 22/04/2021 We swapped Karbonius csl airbox to an Evolve csl airbox. After which a road test of 80km was performed. The air box was inspected for signs of oil ingestion, no oil was found. The breather port was dry, no oil was found dripping from the port down the back of the air box. Spark plugs were pulled and the cylinders showed no signs of oil entering the combustion chambers. Catch can was empty. This confirms that the Karbonius airbox is creating high levels of suction at the breather port and flooding the intake with oil.

Can you take a few detailed pictures of the airbox? Most of the airboxes have the same basic design, so something weird is going on.

[mainstreamer00]

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[wahsm]

Taken from the recent report:

22. 17/03/21 leak down after 100km 5% on all 6 cylinders. Found engine oil in all cylinders upon inspection. Checked airbox found oil in bottom of the box. Checked catch can for oil residue. Found 1” of volume on the dip stick. Removed breather hose to top of air box and found more oil residue indicating its ingesting through the breather system. Cleaned out the cylinders and airbox of excess oil. We suspect the oil is coming from the breather system. To verify we removed the breather hose from the airbox and wrapped the openings in a breathable cloth. The idea is to remove the vacuum source at the air box from the breather system. The car was then driven 80 more kms. The oil injestion has stopped. The airbox and cylinders are clear of any oil resdue. The engine is still on Total Quartz 5000 to complete break in. We will switch to LubromolySynthoil Race Tech GT1 SAE 10w60 after 300kms.



23. 22/04/2021 We swapped Karbonius csl airbox to an Evolve csl airbox. After which a road test of 80km was performed. The air box was inspected for signs of oil ingestion, no oil was found. The breather port was dry, no oil was found dripping from the port down the back of the air box. Spark plugs were pulled and the cylinders showed no signs of oil entering the combustion chambers. Catch can was empty. This confirms that the Karbonius airbox is creating high levels of suction at the breather port and flooding the intake with oil.

You mentioned they swapped the evolve airbox from another shop car. Have they tried putting your intake on that car to see if the problem can be reproduced on that other car?

[heinzboehmer]

Hmm, a couple things stand out to me from that report.

First, was the leak down test repeated after the cylinders were cleaned? The oil that was in there might have made the leak down numbers look better if it was helping seal along the piston rings.

Second, I would measure the pressure at the port on both airboxes before blaming anything. It feels like too many variables were changed at the same time to immediately place blame on the Karb box. Pressure numbers are indisputable and will tell you if the airbox is truly sucking in oil or not.