Hey everyone I have a 2002 Mini Cooper s, for quite some time now I’ve noticed a good amount of black smoke coming out of the exhaust, mainly when cold and giving it a small amount of rpm, and when warm, and accelerating harder. It’s not a lot of smoke, but it’s there and seems to dissipate quickly. I had my mechanic driving behind me the other day, and he said all he could smell was oil and unburnt fuel. I’ve done a compression test and all checked out well. I’m definitely using oil, and I’ve noticed my coolant is quite brown, like light coffee, or mud. It was also slightly low. This is decently new coolant as well. Probably 20-30k on it(not new, but not old). One of my other symptoms is that my oil became black very quickly last oil change, so I got it changed early the other day, and noticed the end of the stick to have a milky color. I always drive long enough to warm it up and some. I’ve checked my pcv valve and it’s in good shape and no oil in the hose at all. Dry as a bone. Does anyone have any idea on some possibilities? I’m leaning towards the head gasket. Any help would be great, thanks!

How many miles on the engine. Sounds like more than one problem. Chocolate shake looking oil is coolant in the oil. The oil turning black quickly is from blow by past the rings, which means cylinder wear and is also whybthe black smoke. The unburned fuel smell means running rich, which may be causing the cylinder wear from washing the oil out of the cylinders. Most likely a head gasket leak causing coolant leak. While the head is off inspect the cylinder walls.

Oil turns dark the moment it is exposed to oxygen and heat? Where did you learn this? Please provide a source of this info other than your opinion please. My experience has taught me that oil darkens over time from the products of combustion being washed out of the cylinders or blow by. I last changed my oil about 3000 ago and it still has an Amber cast. Oil darkens over time because it is gradually getting dirtier, which is one of its jobs besides the primary one of lubrication. Also, the OP said the oil on the end of his dip stick looked milky which probably means water in the oil.

Hey everyone thanks for all the responses!! I’m definitely going to look into the oil cooler issue. That would be much easier to do than the head gasket for sure. I’ll do some research and compare symptoms. As far as possible seals and guides, what would be the better option, getting the head done, or replacing it all together? And does anyone have a clue what could be causing a rich condition? I feel like it would be a sensor but I have no codes.

One other thing I meant to mention referring to the oil consumption, with my oil cap off, I get a good amount of airflow out of the cap. One of the mechanics at the shop I work at claims this is totally normal on a supercharged engine, but there’s no way it’s normal, I’ve seen videos of the r53s doing this leading to the pcv, but my valve can flow one way and not the other, and there’s no oil inside the hose at all. Could it still be bad? Or maybe a possible vacuum leak in the hose to the pcv? Is this common? After checking out symptoms for this, it mentions it causing black smoke, oil consumption, moisture build up in oil, seals on engine leaking, which I do have a decent amount of.

Is that the only possible reason for the pressure? Blowby from rings? Or could there be another cause?

I’m no specialist on super charged engines but it is not normal to push air out of your oil cap. Black smoke is oil. Burning oil is either from bad ring or rings and/or valve seals leaking. If the smoke is continuous then it is most likely rings. I’m not sure if oil can leak past an intake seal on this engine as it can on a V8. Someone else may be able to speak on that. Have you done a leak down test? I see you did a compression test, which can show good numbers even with leaky rings.

You Tube

Here is a thread that shows how one member tested the oil cooler. It’s at post #7. https://www.northamericanmotoring.co...ml#post4288888

I have not yet done a leak down test, but I think it is my next step in the process. I also wanna try the combustion gas tester in the coolant, but I couldn’t locate the tool locally so I’ll have to order it online.

Any luck yet?