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Discussion Starter #1
I have a 2006 BMW Z4 3.0si with 94 k miles on it. I did not buy the car new, so I have no service history. Recently, there is the odor of oil fumes in the cabin. From other posts, I have almost come to the conclusion that the oil separator valve is in need of replacement. When I remove the oil filler cap there is a vacuum sound. I have a good set of tools and moderate mechanical skills. I would like to know from those of you who have "shade tree" experiencing in changing this valve on a car like mine how difficult a job it is. When you did change the valve did you also change the related hoses, etc? I would also welcome any other constructive comments anyone wants to make. Thank you for reading this post.
 

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It's more likely a valve cover gasket leak. Check on the passenger side of the engine for oil residue.
 

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Agree that the valve cover gasket is likely leaking. When you change it ensure that you clean all traces of oil from the exhaust splash guards and anywhere else. Pay attention to "under hanging edges" and ensure they are clean. This will allow you to see if the new valve cover gasket is installed correctly/torqued to specification. It will also eliminate the burning oil smell right away on flash up ... After the change.

I also would change the Crankcase ventilation valve as well. It's likely in need of changing...
 

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If you do replace the CVV... Here is something I wrote on another forum....


"Likely crankcase ventilation valve is getting clogged due to the cold/sludge build up. Replace it/hoses with the winter version ( insulated). There is a trick on how to connect the hose to the CVV that goes up through the intake manifold. It needs a quarter turn to engage... Put hose in place .. Put CVV in place... Rotate hose top end back towards center of engine while pressing hose at CVV end in with screwdriver against the hose (with everything lined up...). It should now move forward enough into CVV to rotate hose at top back towards fender and engage (1/4 turn required...). You might have to push the hose top end down at its halfway point between the intake manifold to get the 1/4 turn required as you push the bottom end into the CVV with the screwdriver. Took me 5 min... That's of course after spending an hour figuring out the trick...."

Should you decide to do change it....
 

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check6
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Discussion Starter #5
oil valve separator

Thank you both for your response. The valve cover gasket is indeed leaking and will be replaced. I also plan to replace the CCV system. Thanks for the instillation tip.
 

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The most common failure of the oil separator happens on Northern cars and it's a cracked body due to accumulated moisture freezing while the car is sitting out overnight, and then you have some oil leakage on the driver's side of the engine and a vacuum leak. It's pretty rare for oil from the separator to cause smoke because it's on the intake side of the engine. If you remove the oil filler cap and you have vacuum, the oil separator is at least not clogged, and is likely still good. There's no harm in replacing it, just might not be necessary to address the oil smoke symptom you're trying to fix.

This is a good DIY for the valve cove gasket replacement. It's done on an X3 but aside from all the plastics he has to remove to get to the engine, the job is the same on the Z4. You'll likely find you have a couple of the bolts that hold the valve cover in place broken, and that's why you have the leak.

https://youtu.be/tdtnG1kqtjo
 
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