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Stock Problems/IssuesDiscussions related to warranty related issues and repairs, or other problems with the OEM parts and software for MINI Cooper (R50), Cabrio (R52), and Cooper S (R53) MINIs.
Just purchased '06 MCS Cabrio R52 with 110k miles. The car has a slow oil leak that I didn't catch before I bought it. The oil quantity is just enough to leave a quarter size spot on the driveway when I bring it home overnight. The leak may be most pronounced when parked on a hill because I didn't notice it until I started parking in my sloped driveway.
Climbed underneath and it's apparent this has been ongoing since there is oil residual everywhere. The thickest/center point of the leak seems to be this part. It is located just aft of the engine before the firewall. I had trouble seeing the whole part so I can't quite identify what it is. While I suspect its oil cooling related, it almost looked like the back end of a starter. It felt like it was flexibly mounted, I pressed it and it had some give. Looking at RealOEM, this oil pump with drive is all I found that would be my best guess? Anyone else help me identify what this photo is and if it might be a likely source of the leak?
The part I am asking about is in the upper left of this photo. In this photo it looks like a solid black canister just to the left of the nut with cotter pin (and in the background relative to that nut)
Here's a list of items, top to bottom (some more prone than others) to leaking oil/fluid on an R52/53:
Valve Cover Gasket
Spark Plug Tube Seals (4)
Camshaft Position Sensor o-ring
Crankshaft Position Sensor o-ring
Timing Cover Gasket (less likely to leak)
Timing Cover Crankshaft Seal
Rear Main Seal
Oil Housing Gasket
Oil Cooler/Exchanger o-rings (2)
Oil Pan Gasket
Oil Drain Plug
Power Steering Hoses (2)
The part you are referencing is the power steering pump. The hoses above may very well be leaking, but that said, there is oil well forward of the p/s pump (visible on forward underside of gearbox), which leads me to perhaps the most common leak of all, the Crankshaft Position Sensor o-ring on the front-side of the engine block. It's also on the same side of the engine that most of your oil seems to be coming from. Oil leaks out, runs down the front of the block, and as the car is driven over time, blow-back coats everything behind it with oil.
Best course of action here is to get dirty and clean everything underneath so in the coming days/weeks you can see where fresh oil is coming from, then fix the leak. Beyond that, a methodical tackling of everything on the list above will make the engine of your MINI dry again.
It's definitely a rite of ownership. There's no shortage of challenges to stop the leaks!
AoxoMoxoA has the list above as your checklist of all the usual suspects.
Spend the time to clean EVERYTHING up. You'll become obsessive about chasing down each spot and drop, til you can id the fluid just by looking at the color of it. By the end of it, you car will be leak free, but you'll continue to be paranoid and inspect and check for leaks every week or so...(don't tell me I'm not the only one that does that!)
which leads me to perhaps the most common leak of all, the Crankshaft Position Sensor o-ring on the front-side of the engine block. It's also on the same side of the engine that most of your oil seems to be coming from. Oil leaks out, runs down the front of the block, and as the car is driven over time, blow-back coats everything behind it with oil.
I've had the problem for as long as I've had my R53 it seems. I've replaced that damn O ring more times than I can remember. Anyone have any secrets for sealing this thing for good, once and for all?
Best course of action here is to get dirty and clean everything underneath
Thank you so much for the help. I'll plan to clean everything up and try to isolate the leak as soon as I can. I'm sure I have some work to do, hopefully I can tackle that list over the next few months/year and not weeks!
So I was finally able to make some time to clean under the motor and take some better pictures. I didn't have hours so I didn't get it that clean, but close enough to get a start on my obvious leak first.
The power steering pump is obviously covered in oil or power steering fluid. I think replacing the hoses is where I'll start.
The rest of the engine block is a little oily. The front of the motor (passenger side of the vehicle) actually looks pretty OK. The portion of the motor that faces towards the back of the car is where some significant oil staining exists. It could be blowback from the power steering fluid. But it does kind of look like engine oil in a few spots near the oil pan gasket.
Two questions for anyone with the time:
1) Any thoughts on leaks based on what you see in these photos?
2) Any concerns on that engine mount bushing? It looks like it might be OK internally, but the outside rubber is tearing away as you can see in the photo.
Mahalo!
The power steering pump is clearly covered in oil, most likely power steering fluid. This is the plastic intake for the power steering fan. It was covered in oil/fluid inside and out. This circular hole sits right on the power steering fan and right below the power steering hoses. Here, just above and beyond the engine mount, is a drip of oil that has come from somewhere above. The block is pretty oil saturated. The bottom silver pan in this picture is the oil pan. There is a collection of oil seeping right at the oil pan gasket. Either the gasket needs replaced or that lip is catching oil from above. Not sure what I was hoping to show here. The block (left side of the photo) is pretty oily.
Two questions for anyone with the time:
1) Any thoughts on leaks based on what you see in these photos?
As I alluded to in my first post, I think a large part of the oil you're seeing originates from the front of the engine in the form of a bad crankshaft sensor o-ring, which will distribute oil on the underside via blow-back. The oil both ON and INSIDE the p/s fan intake tube convinces me of that.
As to the oil on the back-side of the block, it's almost certain that you have a valve cover leak that's running down the back-side of the engine. You'll be able to tell by studying the rear of the valve cover, above where the heat shield bolts on. There are a series of "tabs" that protrude from the top of the head around the perimeter of the valve cover (see arrows on photo below). If the v/c gasket is leaking, these tabs will be wet with oil.
I'd take care of both those before incurring the expense of replacing the p/s hoses. My guess is that most of what you're seeing on the bottom of the p/s pump is engine oil and not p/s fluid. Have you checked the level in the p/s fluid reservoir? If the hoses are leaking that much fluid, you're bound to be low there...
Of course, this is not to say that any of the other items on my list (post #4) aren't leaking as well, but I'd start with the two I just mentioned.
Originally Posted by nomar116
2) Any concerns on that engine mount bushing? It looks like it might be OK internally, but the outside rubber is tearing away as you can see in the photo.
I'd change that mount. It's shot for sure.
Last edited by AoxoMoxoA; 09-20-2018 at 05:07 PM.
Reason: Clarification
I'm planning to tackle this project Saturday or Sunday. My plan right now is to verify and then do all three things you have suggested (valve cover, crankshaft position sensor o-ring, and lower engine mount). The power steering fluid was maybe 1/2" below the top of the reservoir, so pretty full. That's the first time I've checked it.
I'm also going to investigate the other engine mounts and the front brakes. I have a SES light and the brake indicator illuminated. It just started giving me a bit of a shimmy / noise under heavy braking yesterday and today.
Check the camshaft o-ring as well. (passenger side of motor underneath the u-shaped motor mount bracket.) Shoot some brake cleaner in that general area to clean it up and look for fresh seepage. If you find some, replace the o-ring when you're doing the valve cover. Also a great time to do your motor mount too since you're right there.
Your last shot where you said you were not sure what you were hoping to share, that's the oil filter housing mount to the block. Looks to have a drip of oil on the lower bolt. Won't know if the seal has failed until you clean up the potentially leaking valve cover first. Start from top down like AoxoMoxoA advised and eventually, the motor will be dry.
When I replaced the crank pos sensor o-ring, I also used red RTV sealant to help seal against future leaks. This was done about a year ago, and so far, no leakage.
09-05-2018, 12:26 AM
