Hey all,

Most of the exhaust smoke threads I've found seem to end up being turbo issues, and I don't think that's what I have here so bear with me.

Bought a 2011 Cooper S Hardtop last winter and for the last couple of months it has periodically had oil smoke in the exhaust. It is usually pretty sporadic and I haven't really been able to nail down an exact sequence of events that causes it. Most of the time it's just a light plume but 2 or 3 times it's been a James Bond-esque spy smokescreen. It seems to mostly happen during periods of moderate throttle after sitting still or coasting. Seems that really giving it the beans for a little bit clears it out and I won't see it again for a few days. I never see any at startup or while idling after a start, only after a minute or two of being underway.

In the last two weeks or so, however, I've noticed that the smoke has been accompanied by a nice invisible cloud of burnt-oil stink that sits around me if I'm driving slowly or sitting still at a traffic light, getting into the vents and really stinking up the place (leading me to believe it's coming from in front, not just behind). It also has started having an oily residue around the left rear corner of the valve cover, around what looks like it might be a cap, but isn't removable (at least with the amount of effort I gave it before figuring I'd just break it).

This picture shows the area of the oily residue (in retrospect, it was taken from the worst possible angle to see the oil, but it congregates down in that valley and to the rear around what looks like a vent).



When I open the oil filler cap with the engine idling, there is a surprising amount of positive pressure and once unlatched the cap wants to blow off, shooting steam/smoke and oil droplets in the process. I could have sworn that I've read there is actually supposed to be light vacuum when you do that.

The car has consumed about a half quart in the last 1000 miles, I'd wager. I don't know if that seems high anymore - I also own an EJ25 Subaru WRX, so my perception of normal oil consumption is all out of whack.

Car has 26,000 miles and is otherwise in tip-top mechanical shape. No driveability or misfire/stumbling issues. I checked the small tube between the valve cover and pre-turbo intake hose and it only had a very small amount of yellow-brown residue, only detectable by shoving a paper towel inside. No visible oil or sludge present.

So, does this description seem like the PCV system is operating correctly or am I correct in feeling that it isn't exactly working the way it should?

 

A half quart for 1000 miles of driving seems a little much given you have an N18 engine, normally they burn very little to none at all. There's only so many ways oil can enter the combustion process, valve seals, head gasket, piston rings, intake tract from the turbo. It's possible oil is dripping onto the exhaust externally from the valve cover gasket or a crack in the valve cover, do you see smoke coming out of the tail pipe?

 

Under that cap thing you couldn't get off is a rubber seal with a spring. Seems to be a pressure relief of sorts. Don't try to take that small cover off, the tabs holding it on will likely break, mine did. That plastic is thin and brittle. Not sure if that's any help, just an fyi.

 

My '07 N14 MCS had a similar problem, oil use and bad smells, caused by my mods --- OCC and blocked PCV line to the manifold (which isn't on the N18). My positive crankcase pressure was causing oil to get thru the turbo oil seal into the turbo air inlet chamber. This can be verified by removing the turbo air inlet plumbing and examining the inlet for oil residue. It's supposed to be dry. If not, since your "up-stream" air inlet hose is "comparatively" dry, the turbo oil seal would probably be the source. This doesn't mean the oil seal is shot, it just means oil takes the path of least resistance. I fixed both oil use and smells by re-connecting the PCV line to the intake manifold.

Chances are, your valve cover PCV system is faulty. There are other causes for positive crankcase pressure, and all should be checked before replacing anything --- a compression / leak-down test is probably the best test for this issue --- AFTER you check for oil in the turbo air inlet.

Keep us posted with test results ---

 

That's sort of what I figured, but wanted other opinions to be sure. Definitely smoke in the tail pipe. Under the right conditions, I can lay quite the smokescreen. Part of me wondered if it was just the Germans trying to inject a little bit of that old British car charm.


Thanks. Definitely stopped pulling on that once I encountered enough resistance to guess that it probably wasn't supposed to come off on it's own.


I will pull the intake hoses and possibly the intercooler (depending on how much free time I can scam) this weekend and see what I see. Hopefully this can just be corrected by replacing the valve cover. I may do a compression test as well, but I'm not that worried about piston rings or valve seats considering that the engine runs so well and the fact that the car only has 26,000 miles on it.

I'm about 5 hours away from the closest MINI dealership, so getting this done under the small shred of warranty I have left isn't going to happen, unfortunately.

Now if I could just figure this thing out, kill that seatbelt gong once and for all, and get the car to stop barking orders at me in German, we'll be good to go.

 

were you ever able to resolve the issue with the smoke at idle and coasting? I've got a similar issue now.
They make a thing called chime defeat for the seatbelt gong.