Hello, I have an S430 4matic with 145000 miles. I got the car 1k miles ago and it had some oil residue coming from the oil filter cap that had dried on. The rest of the engine looked clean and I assumed it was a bad seal on the cap and someone didn't clean the engine off. Last week I noticed some oil residue on the first 2 driver side coil packs coming from the air filter area above them. I popped off the front plastic cover and noticed a bit of oil in the corners of the air filter holder where the intake tubes connect on both sides. I haven't removed the plastic with the engine air filters yet. I have new filters but didn't want to install them until I looked into this issue. I read on some other models that there is a pcv system that needs cleaned or it leaves extra oil in the intake box. Not sure if that's an S430 issue.

- Any idea where this oil would be coming from and is this a common issue?

 

Did some more investigation. The oil I thought was coming from the air intake was actually black glue someone used to hold on the pretty plastic top. Replaced the filters, the whole air-box was clean inside.

With the air-box removed, I saw some oil residue on both of the valve covers. Much more so on the driver side.

On the Driver side it looks like the oil fill cap might be seeping. On the Passenger side, it might be a gasket for a small cover on the top of the valve cover. I cleaned up both sides and we will see if/where the leak emerges.

Pictures below

 

The "oil" in the air box was just glue holding the trim cover on the air box.

dirty, especially the dark bold opposite the third coil from the top. That was really gooped

clean

dirty, specially around the oil fill cap but ran onto the first two coil pack

clean

 

150k MILES?
Just clean it up a bit and watch it.

 

Might be valve cover gasket. At least on the V12, mine turned into brittle plastic from all the heat so there was a lot of seepage.

 

I have never seen a W220 that was over 100k miles THAT DID NOT HAVE THAT CONDITION IN THE AREA YOU HAVE CIRCLED IN YELLOW. That is normal condition. Nothing to be concerned about.

 

Yeah, thanks all. I guess this is a common issue of the engine breather cover gasket. It's comforting to know this.

Thankfully the actual valve cover gasket looks ok. Even so, It looks like a time consuming process of cleaning out the gasket for the engine breather cover.

How long is it ok to just keep going like this before it needs to be dealt with? Or is it just a matter of when it gets bad enough to bother you?

 

As suggested, clean it first - perhaps with spray cans of brake cleaner - then see how quickly the stains reappear. If it takes hundreds or thousands of miles, just try to avoid thinking about it...