1st Gen R53 Cooper S Most liked posts in thread: Oil Leak?

I wouldn't be tasting any drip samples unless they are beer. :beer

Dave is right about the color of those fluids & the sweet smell of antifreeze. Since you are still under warranty I'd be visiting them with a request to please fix the leak.

Good luck, let us know what it turns out to be.

 

I have also been known to mouth siphon Meth, :crazy: but that's a different story for another time.

 

I'd guess it is the thermostat housing or possible a PS line. Check the PS tank & top up is needed with the correct Pentosin CHF11s fluid.

These are cars & cars leak weep & seep fluid sometimes. As long as you are checking things & aren't having to keep adding fluids at an alarming rate I would not worry too very much. The key is keep opening the hood & check things.

 

Another possible candidate on an '05 in that location is the motor mount.

There should be easily visible evidence from above if the diaphragm in the mount has popped (i.e., discoloration of the frame).

 

What color is it? Oil or Blueish because it could be a coolant leak.

An easy way to check is use a white paper towel and blot the spot off the ground. See if you can tell the color. Take a little tiny taste and if it's sweat its coolant. You will also be able to smell if it's oil.

 

If it is really over towards the front right wheel, I'd be guessing washer fluid or maybe power steering. On the R50/53, the two tubes that go from the PS fluid tank to the PS pump and rack (down low on the subframe) are notorious for leaking. Sometimes just re-crimping the connectors will fix it. I had them use normal hose clamps when I had them replaced, so I could check and tighten 'em myself the next time (they require a band crimping tool... fast for the factory, but one more specialty tool I don't wanna buy). I also had both of the high/low pressure lines to the PS pump replaced due to leaks (around 80k miles).

Almost every 5-6 year old R53 I've looked at had a small amount of oil dripping from the crank sensor hole. It is directly behind the radiator fan on the engine block. Oil from there usually drips down, then is blown back across the bottom of the oil pan. There is a replaceable o-ring that seals the hole and usually wears itself flat in a few years. A $13 part and an hour or so of wrenching... I wrote a how-to article that is in the library section of this site.

Crank Sensor Seal Replacement - Library

 

If it is thick and very sticky, my bet is upper motor mount mount. Look right under mount, it will be on frame right under it.

 

Thick oil does suggest the damper.

Here's a photo of one from a '06 MCS (should be the same as yours)



The black sludge along the white frame rail is from the oil that is contained inside of the metal can. It tends to run down the frame rail (painted white in this photo with black crap in all of the edges and creases) under the damper or straight down from the damper to a spot just inside and forward of the passenger side front wheel.

If you pull the front passenger wheel off and remove the plastic wheel well liner, you will get this view if you lay on your back and look up... you can see all of the black sludge from the damper's oil leaking down...



I did a how-to on fixing this a few years back. I augmented my transmission mount as well, but there are instructions included on how to skip that step and just replace the engine mount.

Powerflex Transmission Mount Bushing Install w/ Upper Engine Damper Replacement - Library