E46 N42 pressurising - oil breather?

[Brian28]

My car was leaking oil from the oil cap, I changed the oil cap and it's still doing the same. Seems like a stuffed breather pipe. I have been driving it the last few weeks with the dipstick slightly out so it blows/leaks the oil out there instead and not over the exhaust manifold from the filler cap, have a bit more time next week to have a proper look at it. I'm new to these engines (I've had the car a couple of years but have only done oil changes), is there likely to be a breather blocked and if so where do I start looking for it?

[alpina123]

these engines really are crap for it mate it is likely that its the cam cover gasket though or the cam covers cracked

[bss325i]

Yes the cyclone valve (breather) does block and the associated pipes go brittle and crack/split.

The cyclone valve is under the inlet manifold and you need to remove that to change it.

Common oil leaks from the N42/N46 are,

cam cover gasket
Vacuum pump
Vanos solenoid seals
sump gasket
Breather pipes

As said, the N42 is a shit engine, one of BMW's worst IMO and they suffer from all sorts of other problems.

Best avoided but keeps me busy!

[Brian28]

Thanks for replies. The primary leak was def pushing oil up through the filler cap, hoping that venting through the dipstick pipe has stopped it from pressurising and blowing too much else. Was never a completely dry engine, but now pushes out over a litre a week. This looks like the bit I need? The car has always ran nicely (touch wood) so hoping to get away without splitting any of the pipes on the way in/out.

http://www.ebay.co.uk/itm/BMW-3-SERIES- ... 19c44c58fc

Cheers

[bss325i]

Yes that is the part and I would always replace the pipes at the same time as,

A) the chances of one breaking are high and you don't want to be in a situation where the car is in bits and you have to wait a day or two for parts.

B) If you are lucky and none break, you don't want to be pulling the inlet back off again to change them when one splits further down the line.

Removing the inlet on one of these donks is a bit fiddly and if you've never done one can be quite frustrating.

Might be a good idea to do the crankshaft sensor at the same time of its never had one as they are common for failing and its also an inlet off job.

[Brian28]

Top job thanks, will get the lot ordered up and sort it one day next week.

Cheers
Brian