This is a 2019 S560 with the M176 engine. While doing an oil change, I found oil on the crankshaft position sensor and trying to figure out where it’s coming from.

I’m guessing it’s dripping down from a higher point (like valve cover, etc). and not the rear main seal.

Does anyone have any suggestions on what it might be or how to best diagnose it?

 

Most likely a valve cover leak. Do you also smell any burning oil? They often drip onto the exhaust manifold causing the smell.

 

Valve cover leak...common

 

Clean the area thoroughly with brake cleaner. Then run the engine and look for the leak. On that engine, the most common source is the valve cover gasket at the rear. Oil runs down the back of the engine and pools on that sensor. It's rarely the rear main seal.

 

Thanks for the feedback. I will be getting under there this weekend to replace the transmission fluid, and will take a look up and see if I can see the leak at the cylinder head cover.

 

Get out the big checkbook for that valve cover repair unfortunately.

 

So I got under there to do the trans fluid and got some more photos.

I looked up, and I don't see a hint of oil. I think it's probably leaking from the rear main seal... what do you guys think?



Bottom of tens (Center)

Bottom of trans (Passenger)


Looking up above the sensor

A litle closer

 

Yours looks like a fairly significant leak. I thought that if the valve covers leaked bad enough you would smell buring oil on the exhaust, but not 100% certain. But like you said, the area above looks super clean, so I doubt it's the valve covers. Yours looks like a leak from below, most likely the RMS based on the quantity of oil and how it's all over your sway bar, I say that because it looks like the wettest part is between the engine and transmission. Maybe you could have an oil line leaking somewhere, that might be best case scenario. But like he said above; it's time to write the BIG check. Hope you have a good indy, or better yet, a warranty.

 

Did you pull the back two plugs and look for oil? If there is no oil in there its the RMS...