While working on my car I noticed a significant amount of oil residue on the under tray (brush guard, belly pan). The oil residue was on the passenger side in the area of the exhaust, and where the engine mates with the gear box. After removing the under tray and doing some investigation I found that the valve cover was leaking at the back corner of the engine.
After some research this seems to be a common problem on the N54 engine. The engine leans to the passenger side of the vehicle, over the exhaust. The exhaust manifold and catalytic converters exit the engine compartment towards the back. The back of the engine, where the number six cylinder is located, tends to experience higher running temperatures do to the lack of cooling towards the back of the engine, and the heat being expelled from exhaust system. The lean in the engine means oil accumulates along the top edge of the valve cover on the passenger side of the engine block. As the gasket gets older and brittle, oil begins to leak on the back side of the engine. This can be dangerous if the gasket has a catastrophic failure as an excessive amount of oil may leak on to the exhaust system causing a fire.
I decided to replace the valve cover gasket myself. It took me about five hours of work to replace the gasket. You have to remove a lot of components and wiring from the top of the engine, before you can remove the valve cover. The micro-filter trays, strut tower brace, engine cover, coil packs, fuel lines, wiring harnesses, and vacuum lines need to be removed , detached or moved out of the way. Once you do that you can pull the valve cover off. The valve cover was very difficult to pry off the engine. I used putty knife to get in between the cover and the head. Be careful no to crack the cover or scratch the surface of the the head. Obviously a cracked cover will cost you more money. However scratches or gauges in the engine head surface, if severe enough, will not allow a seal to form and the gasket may leak.
All-in-all, doing this myself probably saved me around 900-1100 dollars, depending on the shop. I live in NJ and quality independent shops are not much cheaper than the dealership. One local BMW shops charges $180 dollars an hour. A 6 hour job would end up costing about $1080
The following is an outline of the gasket replacement. I will post a more detailed steps in the future.
- Remove the micro-filter trays.
- Remove the air filter box
- Remove the passenger side strut tower brace
- Remove the engine cover.
- Remove the Coil Packs
- Unplug the Fuel Injectors
- Detach the wiring harness from the valve cover
- Remove the fuel rail and lines
- Remove the Vacuum Lines
- Remove the Valve Cover
- Replace the gasket
- Install the valve cover
- Put everything back 😉