Common Problems With The BMW N42 and N46 Engine
The BMW N42 engine was produced between 2001 and 2004, the N46 engine replaced this and was produced between 2004 and 2015. If your BMW was produced between these years, it is likely you have one of these two engines.
A common problem that can occur with the N42 and the N46 engine is the rocker cover gasket leaking, also known as the cam cover gasket.
The result of this is oil weeping down on to the hot exhaust heat shields, or the exhaust manifold themselves. This causes smoke from the engine bay and a smell of oil in the ventilation system, as well as the obvious loss of engine oil.
Why You Should See a BMW Specialist
We would always recommend seeing a BMW specialist for any issues that occur with your BMW, as they have the knowledge and experience to fix problems efficiently and are familiar with common problems that can occur with certain makes and models.
At Power Developments, we provide BMW servicing to ensure your car is running efficiently and to identify any issues before they become too problematic or damaging. We inspect all problems manually to ensure we get to the root of the problem and fix it efficiently rather than a process of elimination.
It is this professionalism and expertise we have built up for our reputation internationally as a top BMW specialist, with owners from across the UK and Europe visiting us in Essex to have their car serviced, maintained and fixed by Power Developments.
DIY Guide to Changing a Gasket on a BMW
Here is a brief DIY guide for BMW owners who fancy taking on the gasket change themselves and fix this issue.
All you will need for this engine repair is a decent set of tools. There is no special equipment required, and the valvetronic motor doesn’t need to be removed as the cover runs overs it.
Start by removing the engine covering, cabin filter (micro filter) and the housing that the cabin filter sits in. There will be some TORX screws holding it down.
You should then see this:
In the above picture I have removed the ignition coils, and started to move the wiring out of the way, which makes life much easier.
You must remove the eccentric shaft sensor connector, this is the round black connector you can see in the above photo. Be gentle and it’ll pull up without any problems.
Once the wiring is out of the way you should have this:
Now proceed with removing all the silver nuts that hold down the rocker cover.
Once it’s loose you can remove it and you’ll end up with this.
This particular car has previously had lots of engine silicone applied to try to seal it.
This is generally a bad idea and certainly not required to fix the problem.
Here you can see the black silicone, we need to carefully remove all of this without getting any into the engine.
Once you’ve removed the silicone, clean the contact surface using some brake cleaner to leave a lovely oil free finish for the new gasket to seal up against.
Now you need to remove the old gasket from the plastic rocker cover and thoroughly clean the rocker cover on the inside, paying particular attention to the gaps where the new gasket sits.
This must be oil free so be sure to take your time doing this bit.
Old gasket removed.
With the cover now cleaned and ready to install the new gasket, push this on and ensure it’s even and flat. Note that there are 2 gaskets for the cover, 1 smaller inner gasket and the larger outer gasket.
In this picture, I am also replacing the eccentric shaft sensor seal, I advise this is replaced at the same time, but this is up to you.
Fit everything all back onto the car and reinstall the nuts loosely until they are all in place. The begin tightening them from the inside to outside.
Refit the coils and wiring then run the engine and inspect for leaks. Once everything is confirmed to be ok, refit the cabin filter housing and coverings. Then clean any old oil mess off your engine – voila, all done!