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Green rubber particles in oil filter - Variocam actuators?


New member
11 Nov 2020
Hey all,

Changed the oil and filter in my 98 3.4 today, and found a whole heap of green rubber particles in the filter:



There was no particles inside the filter, they were all trapped on the outside. Thankfully no metal particles either in the filter or sump (decanted oil through a filter and a magnet). One or two small rubber particles came from the sump, so I'm going to get more oil and another filter and do a sump off oil change shortly.

This engine had a full rebuild about 15-20k miles ago (Not Hartech etc, done by a specialist here in Ireland), and the all of the chains & wear pads (along with the pads on the variocam units) were replaced. I do know I have one dead solenoid - and I have a pair of new ones ready to go into it.

The green debris in the filter does point towards the solenoid actuator O rings from what I've read, which means a complete actuator replacement :eek:

So, with that in mind, couple of questions:

1) Are there any other green O rings that could cause those sort of particles? No leaks around the plug tubes etc, no oil pressure issues or funny noises.

2) Has anyone come up with a solution for the Green O rings in the actuator? Seems a waste to change €2500 worth of actuators for a set of O Rings :roll:

An O Ring that is green in colour seems to generally be Hydrogenated Nitrile, which should be relatively easy to get assuming it's not some exceptionally strange size - I would be tempted to buy a second hand one with decent actuators and measure them up to see..
Have you checked the oil filler cap, also has a green seal. Would be a nice find if it's broken up.
DivineE said:
Have you checked the oil filler cap, also has a green seal. Would be a nice find if it's broken up.

I did today, and it was perfect. Interestingly on mine a black seal, I know the filler tube was replaced last year so the seal must have been swapped too..

So, have done a bit more digging, found this very helpful thread on Rennlist:


Showing a disassembled variocam unit. The author (the designer of the Ultimate AOS for the M96 engine) also mentions if that particular green O ring material is present, it's from either the variocam actuator or the plug tubes.

It would appear that the actuators are not meant to be refurbished due to a crimped retaining ring on the bore.. :pc: :pc:
A few seals on these cars can be either green or black .. oil filter cap being one of them .

Oil filter canister can also have a green or black seal on it .

Camshaft end bungs are normally green .

If the car doesn't have plug tubes then there are 6 green seals on the cam cover to stop oil ingress to the spark plugs.

I've never stripped one of these solenoids but if there are green seals in it and you have a failed one then the logical conclusion would be that its from that .

The majority of seals on these engines are black though .
Cheers deMort,

Yeah, that's exactly what I'm thinking. I have two complete actuators en route anyway, so I'll start there and eliminate that (they need to be done anyway) and go from there..

Now just to figure out the cam locking/retaing tools!


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