So I will be making an appointment to bring in my '06 MCS for service to fix and hopefully put to bed this oil leak. This is the 4th time I have been to the dealer for the same issue. The first time they replaced the oil pan gasket, second time they could not pinpoint the leak and asked me to put on some more miles, and the third time they replaced the oil pan gasket once again. So here I am, 2 replacement oil pan gaskets later and I still have a leak.

It's not the motor mount, it's not from the filter housing, it's a small but persistent leak coming from the front of the block and running down the front of the oil pan (why I think they keep replacing the gasket). To the dealer's credit, I did have oil seepage all the way around my original oil pan gasket, but since the 1st replacement I have only had the oil leak from the front of the block area. I'm not sure what is causing this leak, maybe it is in fact another bad oil pan gasket, but what the hell is making multiple gaskets fail? My other thought was a leak from the supercharger or valve cover gasket. I've brought up these suggestions to the dealership and they can't seem to locate a leak in these areas or they don't want to spend the time and man-power to.

The oil accumulates on the front side of the oil pan on the end of the pan closer to the tranny. It's not a bad rear main, at least I don't think so, and they supposedly checked this and ruled this out previously. What else could it be that would cause this kind of slow leak?

My car has ~29k on it, '06 MCS, no engine mods whatsoever, no intake mods other than a K&N filter in the stock box. The leak resurfaces no more than a few days to a week and a half after servicing. Love the car, but there is no reason for a newer car these days to develop oil leaks @25k miles like mine. I'm going to make sure this is taken care of one way or another because the end of my warranty is coming up fast, and there is no excuse to make this many service trips for the same problem like this.

 

Is it leaking down the front of the block?
Have they pulled the radiator and looked at the front of the block?

If not you might have a leaky dipstick tube seal or maybe a crank sensor seal.

I had a slow leak coming from the front of the block. When my car was in getting a performance clutch/LSD they pulled the motor and found the crank sensor seal was leaking. Mine isn't the only one they've seen that one either.

 

From as far as I can tell (and this is only from removing the plastic deflector that is behind the air dam) the oil appears to be coming down from above the oil pan lip, and there was some residue on the block before although it gets covered with dust pretty quickly. It's very difficult to get a good angle and see from under the car, so I never confirmed this 100%. I looked at the valve cover gasket, and that's still dry as a bone, so I've ruled that out. I'll give it a good inspection this weekend and update this.

I doubt they pulled the radiator but I'm sure they'll exhaust as many possibilities as they can this time around since it's the 4th time in for this leak. My take on this is that they seem to quickly look it over and just figure it's a bad oil pan gasket. You'd think that after two pan gaskets they'd want to look into it a little harder, we'll see.

I did read a thread with someone mentioning a bad crank sensor. I'm going to bust out the Bentley Bible tonight and flip around a bit. Off hand, do you know if the crank sensor is located on the front of the block pretty close to the transmission? The oil seems to collect on the front edge of the pan close to the tranny. How many miles did your S have on her when you noticed the leak?

 

Have them clean the engine bay spotless. Have them put the liquid florescent dye in the oil. Drive the car a bit. With a black light look for the leak,no brainer!

 

The crank sensor sits on the bottom part of the top half of the block (if that makes any sense) on the transmission end. If you look at this diagram on RealOEM you can see approximately where it sits (it's part #8).

 

With approx. 15,000 miles on it, brought mine in recently for an oil leak.
It was the crankshaft seal.

 

how long did it take for them to replace the crankshaft seal?

 

Since it's still under warranty, I took it to the dealer. Including check in / check out time, I was there for 2 hours. So...not sure of the exact time for replacement.

 

I had an oil leak that I had fixed last year prior to my warranty running out. The dealer replaced the oil pan gasket, as well as the valve cover gasket.

I took a look under the car at lunch time...and damnit, it's moist under there again! Not enough to drip on to my driveway, but the oil pan is getting moist. With the splash shield removed, I saw that it is coming from above the oil pan, behind the supercharger. I couldn't see all that well, but there was a gray tube that runs just behind the supercharger (not the dipstick tube) and it almost looks like it is weeping right where this tube connects into the block. Since it was really hard to look back there (talking about going cross-eyed), I can't say for sure, but that tube even looked like it had a quick disconnect fitting where it goes into the block. Anyone know what this tube might be for?

And does anyone thing I could still get this covered under warranty, as I originally complained about an oil leak and well, the engine is still leaking...

 

I think the grey tube is the valve cover breather tube - see details here: http://store.webbmotorsports.com/for...topic.php?t=16 Mine has a pretty big oil mess in this area - think part of it is from the breather tube and some may possibly be from the supercharger.

 

I'll relate a recent experience for you, FWIW. My wife's 05 Volvo XC90 developed the same problem last year at about 35K miles. Quarter size spot of oil on garage floor overnight, every night. Multiple trips to dealer, various parts changed, to no avail. Very hard to tell where the leak was coming from. To make a long story short, eventually found that the oil was leaking THROUGH the block.

Evidently when engine blocks are cast it's normal to have some small voids (air bubbles). On this block there were enough of these voids that were connected somehow and the oil eventually found its way completely through the block. There was no crack; just oil weeping right through a tiny pinhole in the block. Corporate wanted the local dealer to try to repair the block by using a punch around the area to try to seal the defect. I strongly objected to that since we were soon going to be out of warranty. The local service manager was pretty fed up with me and the car by that point and was able to get approval for a new block. Changed under warranty, no problem since.

I wouldn't have believed this could happen...but something for you to keep in mind.

 

That gray tube connects to the PCV valve which is what you are referring to as a quick connect. I would make sure that the hose that goes into the PCV isnt cracked or anything.

 

So it turns out that the dealer replaced the oil pan gasket, once again, along with the crank shaft position sensor o-ring. The pan gasket was internally charged, meaning that MINI corporate determined that since this is the car's 4th oil pan gasket, they are pointing (or giving) the finger at the dealer for not dealing with this problem right the 1st or 2nd time and would not warranty the work, thus the work comes out of the dealership's pocket. It was then driven ~50 miles and rechecked with no issues. I'm not entirely comfortable with this considering that the leak(s) don't begin to show up until after a few days or several driving cycles.

As for now, I'm still expecting to find oil on the underside of my car within the week, at this point it would be ironic if this issue was actually fixed. I'm gonna be on this thing like a hawk now. I hate to say it, but if the leak comes back, there's a real good chance the MINI goes away. Too much headache @ too little miles. I swear my clutch feels 'rachety' now too. It sucks being a slave to one or two dealerships, I don't even know how I'd do this in a state without a MINI dealership.

 

i had the rear main seal and valve cover gasket replaced at 40000 miles. under warranty.

 

Oh believe me, it sucks. I would have taken my car back to the dealership it was repaired at, if not for the $2500+ shipping cost (one way) to get it there. To have an oil leak return after having it fixed (especially on a car as new as this) is simply unacceptable. My 94 Jeep Cherokee with 140K miles does not leak a drop (with a lift kit, it's easy to see!), and it still has the original gaskets/seals.