I’ve only had the car - 2009 S - for a few weeks and have a good sized oil leak on my hands from the passenger side. At first, I saw that the crank seal was incorrectly mounted so I replaced that and it did stop leaking from here. However now I’m seeing quite the leak, especially when under load. The weird part is I see nothing when the car is running and I’m looking all over the front (side) of the motor with the wheel arch removed. The oil clearly sprayed over everything on that side when driving, but I’m at a loss as to where it’s coming from. Any other culprits I’m missing? I’ve checked:
- crankshaft seal
- oil pan gasket
- timing chain tensioner
- valve cover

Would love some insight if anyone has thoughts not found when searching the forum. Many thanks!

 

There's 3 bolts holding the timing chain guides that have o-rings. They might be loose or leaking. Here's a pic from realOEM showing items 13 and 15. Unfortunately, the timing chain should be removed and best replaced to get at them. Here's a good procedure if you want to try it --- https://bmwrepairguide.com/mini-r56-...er-n12-engine/

 

That’s a great idea, I didn’t even think of those. Definitely a more in depth procedure but one that may be necessary. I did notice some oil running down the PCV line going into the intercooler - surely there couldn’t be enough oil in there to actually leak out right?

 

PCV line from back of the Valve Cover to the intake manifold is a common leak source. Either a loose connection or a damaged hose / fitting at the VC. Whole lot easier to check. If there's oil in the other PCV line --- from the VC to the turbo air inlet, you might have excessive crankcase pressure or a bad VC. Not likely your leak source 'cause that hose is on the other end of the engine. If you have a PCV line going to the intercooler, you better get the hose routing verified / repaired by an experienced Mini mechanic.

 

Thank you, I clearly had my diagram mixed up in my head when I was typing this out! I see no leaks evident from the O-ring area for the tensioner guide bolts. I’m going to remove the air filter assembly to see if I can not any leaks from back there. Other than that, I plan to check the Vanos solenoid o-ring and then I’m pretty tapped out with ideas. Can anyone else think of any other places oil could escape from?