Oil leaking from Oil cap.

[Longitudinal4Cylinder]

So.. I bought an E46 316i, with a bit of an oil leak, it wasn't bad and the guy said it's the oil pan gasket, but then I looked at the engine and said, 'the oil is coming from the top, from the rocker cover' so I took it off and I saw that ACTUALLY the oil is coming from the oil cap, so I took it off and I was like, hmm why's it leaking? Had no clue so contacted my dad's friend as he is an 'ok' mechanic and what he said is the following;
"someone has been abusing this car and then the engine got damaged, specifically the Cylinder head and Valves, because as the engine warms up the pressure goes up and the oil gets pushed up to the cylinder head, and up to the oil cap"

If anyone Knows engines very good or knows anything about this and if it's true. Please tell me.
Thanks

[Blaster72]

Well, the mechanic could be right but it could also be the crankcase ventilation hose is blocked or collapsed.

Take a good look at these parts for anything obvious. A good mechanic will check this out first before going for a compression test on the engine.

http://www.realoem.com/bmw/enUS/showparts?id=AY32-...

[Longitudinal4Cylinder]

Thanks I'll ask soon, but not planning to spend too much money. So if it's too costly to fix, I'll have to sell the car. (because my dad will kill me if he hears that I'll be spending £100+) (Not up to me)

[Blaster72]

Fingers crossed its something cheap to fix for you.

[Longitudinal4Cylinder]

Thanks, I hope that too!

[SebringMan]

it sounds like a crankcase ventillation issue which isn't uncommon for BMW. Check and then change the valve, but then also change the oil filler cap.

[E-bmw]

If I am honest, I would say what he says is exceedingly unlikely.

There is a baffle plate under the filler on most if not all cars & there is certainly an air gap also, so the cahnces are pretty much zero in any car I have had the cam cover off for sure.

Very much more likely what has been said above.

What happens with the engine when you remove the oil cap (carefully & away from you with a rag loosely over it) with the engine running.

[Longitudinal4Cylinder]

Don't know. Will have to check as Have not tried it before. And yes there is an baffle plate under the oil cap
1 question is it on warm engine or cold engine?

[Longitudinal4Cylinder]

Oh and by the way, if it is that, then could I continue driving on it for at least a month or so? or will it just 'die' fully?

[njw1]

As said above, it's more than likely the crankcase valve and/or it's associated pipework, very common on that engine. It can be a bugger of a job to change the valve and pipework though, the inlet manifold has to be removed and there is a bolt on the bottom of the manifold which is very inaccessible.

Oh, and to answer your above question, my mate drove his 316ti about for months with a collapsed breather hose, didn't seem to do any harm apart from making a mess of his engine bay and he had to keep topping up the oil.

Edited by njw1 on Tuesday 17th April 22:07

[E-bmw]

Longitudinal4Cylinder said:

1 question is it on warm engine or cold engine?

It doesn't matter.

[Longitudinal4Cylinder]

Well I just checked it on a warm engine, and what happened is, there were a few drops of oil flying up, and the engine became like 'louder' probably because you can hear the cylinders but that's all that happened.

[E-bmw]

There is your proof that the mechanic was talking out of his @rse.

It is as has been said above, your breather is blocked.

[Longitudinal4Cylinder]

thanks everyone for your help. Now i can prove my dad wrong lol
p.s my dad is raging at me saying "there's no point in fixing it"