I just want to add a few points to the already discussed issue of oil leaking camshaft sensor.
This problem exists in my R170 SLK 2 years now.
So, everybody with same problem probably has visited the local M.Benz dealer
and purchased that leaky sensor perhaps more than once.
The part number is the same so, you have no chances of getting that problem fixed. You are only about to spend your money again.
Along with the sensor they should give a brown color o-ring and the oil trap...cable extention as you americans call it. That special rubber seal is blind to one end. This doesnt matter.
You are about to repace all these with new set hah??
Well, i think...the shaft is the part that has to be replaced.
The problem is very common and on a car like that which costs new around 50,000€ M.Benz refuses to fix it.
No doubt, there is nothing wrong with the design of the camshat and its ground surfaces have given at least a hardness of 62 Rockwel (case hardedened to a depth of 0.8 to one mm).
Unfortunately a single rubber o-ring was a totaly wrong aproach to seal the fast revolving camshaft. Rubber o-rings are going to eat out the extremely hard surface of the shaft end, creating a grove on the periphery. This is shown in the attached photo. And if you wish take a look at the shaft ends of modern outboards and at the point where rubber seal touches propeller shaft after of course of let's say three years of operation.
Except is an expensive outboard engine the owner needs to refil the shaft and regrind.
What they should have done is to design a better oil seal.
A cheap but effective solution would be a double seal of a geometry allowing to touch the shaft periphery at an angle of about45 degrees inwards. see photo.
So the oil itself would keep it permanently in touch with the shaft's periphery excerting an elegant pressure there.
Such a seal design will give at least double, trouble free operation time.
This isnt a solution for life either.
A more efficient oil seal is the one which employs a spring and a carbon ring.
Carbon pushed by spring against ground/hardened surface.
Expensive refrigaration compressors use that. To name a few.
Carrier etc. Why they dont do this with our machines. The are so damn expensive. The oil is going to ruin nearby electronics and the expesive controler and you dont care? You are deaf or something and you cant listen to the complaints of thousands of customers of yours whose property is geopardised due to a cheap oil seal design?
Please M.Benz do something about it or someone else is going to take control of this situation.