E46 318i Touring: Oil leak fixed! Rubber rocker-cover gasket was the culprit!

It's about time I got back to wrenching on some Beemers after a busy hiatus, so where better to start than with the massive oil-leak on my E46 318i Touring. The car hasn't seen much use over the winter months, but as I start to need it again for its cavernous load-lugging functions, I figured it was time to spend a bit more time getting it right.

I was going through about a cupful of oil every 100 miles or so (I think that is a pretty favourable estimate to be honest, more like half a litre!) and worse than the cost of all the topping-up, smoke continued to billow from not only the sides of the bonnet (hood) while stopped at traffic-lights, but also straight into the cabin with the blowers turned on. This meant for the last 12 months I have had the climate-control set to full recirculation mode and on low, making de-misting the windscreen a nightmare on colder days.

I could see the oil-leak was coming from the rear left side of the engine, as it so often the case with N42 engines and assumed it to be the vacuum-pump (like with my E46 318ci in this this post), but after removing the rocker-cover (cam-cover) I found it was actually the rubber gasket itself. The thick rubber gaskets tend to harden and go brittle over time and almost completely down the left side of the cam-cover there was noticeable leakage, primarily at the back corner, next to the vac-pump of course. The gap at the rear-left corner was so pronounced I feel you could have slipped a credit-card through with a little force and touched the back of the cam-shaft! This was allowing a constant drip of oil out onto the heat-shield and down onto the exhaust-manifold, as shown by the arrows in the picture and causing most, if not all of the smoke.

Luckily, I suppose, I have been working through the Covid epidemic, so I am classed as a 'key worker' and had a day off, so I managed to blag Euro Car Parts that it was essential work and instantly collect the new Elring gasket (£22, but eBay alternatives are as cheap as £9.50 if you can wait!) and some Corteco White instant gasket-sealant (£7), though they still had me waiting for an hour outside!

Knowing how prone the top-end seals of the N42 are to leaks and not wanting to take any chances of removing the rocker-cover again anytime soon, I slapped on a liberal bead of the Corteco sealant over the vacuum-pump ring and along the entire left-side (lower) surface of the cylinder-head top edge along with the new rubber-gasket. The job does not take long at all (I will post a guide soon), with removal and refitting of the cam-cover only taking around 30 minutes each and that's taking your time...

Needless to say, this has stopped the major part of my oil-leak in this area! Not only has the oily steam stopped from the sides of the bonnet while stationary, the smell/smoke from the climate vents has now ceased and the car is no longer consuming oil at a silly rate, so I would say job done! There is still a tiny weep of fresh oil coming from around this area, but nowhere near like before and, after a run where the engine is warm, there is no dripping pool on the under-tray! For the money I spent, the difference in convenience is worth vastly more! I would have spent the ~£30 I did in oil in a couple of weeks using the car daily, so if you have this problem, it's safe to say this is the culprit and get it sorted!