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Pelican Technical Article:

Oil Leak Diagnosis

Nick Czerula

Time:

2 hours2 hrs

Tab:

$20

Talent:

****

Tools:

Flashlight

Applicable Models:

R56 MINI Cooper Hatchback (2007-11)
R56 MINI Cooper S Hatchback (2007-11)

Parts Required:

Engine oil

Hot Tip:

Work with a cool engine

Performance Gain:

Repair oil leak

Complementary Modification:

Replace oil

The engines used in MINI R56 cars are MINI New Generation engines. MINI New Generation engines are 1.6 liters in displacement, with turbocharged and normally aspirated versions. All aluminum two-piece crankcase construction keeps the weight down, while technology like adjustable camshaft angle and variable valve lift help to keep the engines efficient.

With the new engine design, new sealing technology is needed. The crankshaft seal is a good example of this. It is made of Polytetrafluoroethylene (PTFE). Low friction and minimum power consumption are the main advantages of MINI utilizing a PTFE oil seal. Other benefits include, no sealing problems with dry operation or insufficient lubrication, an operating range of -130°C to +200°C, and a low breakaway torque after standstill.

Other parts of the engine are sealed with molded rubber profile gaskets. These gaskets dry out over time, allowing engine oil to leak. For example, the valve cover gasket uses a molded rubber profile gasket; it leaks at the front and sides. Sometimes at the curve of the cylinder head where a dab of silicone sealant is used to ensure a good fit. The valve cover can also leak from the crankcase breather (along the center near the coils) and crank at the fastener bores.

In this article, I'll go over how to pinpoint the source of an engine oil leak. Problem areas, components and tips on narrowing down the culprits are in the following text. With any leak, it helps to clean the area and monitor it for fresh oil.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Lift and support the front of your vehicle. See our tech article on Jacking Up Your MINI.

This photo shows the top of a normally aspirated engine.
Figure 1

This photo shows the top of a normally aspirated engine. The trouble with an oil leak is it usually spreads all over the bottom of your vehicle, making it hard to determine where the source is. Start by following the oil, you will notice some of the oil on the engine is darker and dirtier; this is the oil furthest from the leak. Follow the oil toward the cleaner area, sometimes even spotless with just a coating of light colored oil. Look for leaks at the right side (red arrow) of the engine from below. Always suspect the crankshaft seal, as it can fling oil up and all over the side of the engine. At the front of the engine (green arrow) the problem would be the oil filter housing, or the valve cover. If a leak at the front of the engine seems to come from the top of the transmission bell housing, check if the sealing O-ring at the vacuum pump is leaking down the left side of the cylinder head (yellow arrow).

This photo shows the top of a turbocharged engine.
Figure 2

This photo shows the top of a turbocharged engine. The trouble with an oil leak is it usually spreads all over the bottom of your vehicle, making it hard to determine where the source is. Start by following the oil; you will notice some of the oil on the engine is darker and dirtier; this is the oil furthest from the leak. Follow the oil toward the cleaner area, sometimes even spotless with just a coating of light colored oil. Look for leaks at the right side (yellow arrow) of the engine from below. Always suspect the crankshaft seal as it can fling oil up and all over the side of the engine. At the front of the engine (red arrow) the problem would be the oil heat exchanger or oil filter housing, or the valve cover. If a leak at the front of the engine seems to come from the top of the transmission bell housing, check if the sealing O-ring at the vacuum pump is leaking down the left side of the cylinder head (green arrow).

Starting at the front of the engine.
Figure 3

Starting at the front of the engine. Note the oil residue down the front of the engine and transmission bell housing (red arrows). Note the darker oil residue surrounding the area, but the center is clean, almost washed off by the oil leak. When looking for a leak, follow this clean area up, until you find the source. The source will usually be indicated by clean light colored oil, or sometimes where the leak stops.

In the previous photo the oil leak stops at the heat exchanger (red arrow).
Figure 4

In the previous photo the oil leak stops at the heat exchanger (red arrow). Note the light staining on the exchanger and how the leak doesn't go any further up on the engine. For this repair the heat exchanger and oil filter housing gaskets would be replaced.

This photo shows an oil leak at the right side of the engine, surrounding the crankshaft pulley (red arrow).
Figure 5

This photo shows an oil leak at the right side of the engine, surrounding the crankshaft pulley (red arrow). The source here could be the crankshaft seal (most common) or from a leak at the valve cover. See the following photo for more info.

When diagnosing a problem with the crankshaft seal you are dealing with oil being flung around the side of the engine.
Figure 6

When diagnosing a problem with the crankshaft seal you are dealing with oil being flung around the side of the engine. Remove the drive belt and inspect the side of the engine. Look for oil starting low (green arrow) and lessening as it moves up (red arrow). On my subject vehicle, there is very little oil near the cylinder head (red arrow). This means the leak is most likely the crankshaft seal, as the oil radiates from the pulley and doesn't come from above. If you find a leak at the right rear corner of the engine, check if the engine oil is being flung from the drive belt to the backside of the engine. On early engines, some timing chain tensioners would leak, however this problem was mostly dealt with under warranty mileage periods. It is still a good idea to check the tensioner to see if oil is seeping out of the sealing washer.

At the bottom of the engine an oil leak can be from the oil filter housing as previously noted, or driveshaft axle seals.
Figure 7

At the bottom of the engine an oil leak can be from the oil filter housing as previously noted, or driveshaft axle seals. Although not an engine oil leak, these seals are often misdiagnosed as engine oil leaks. Note the wet oil stained area around the right axle and the fresh oil leak at the bottom of the bell housing (red arrows).

Leaks at the top of the engine are usually from the valve cover.
Figure 8

Leaks at the top of the engine are usually from the valve cover. Constructed of plastic and sealed to the cylinder head using a rubber profile gasket, the valve cover can leak a few different ways. Check for oil leaking from the seam at the cylinder head but no stains at the top (red arrow). This would indicate a gasket issue. Oil leaking at the center could be a faulty breather assembly, internal to the valve cover. Oil from the breather can also fill the center bolts holes (yellow arrows). Now keep in mind, the valve cover can also crank in the areas of the fasteners, creating an oil leak. If you suspect the crankcase breather or the cover has cracked, remove it and inspect it. For either of these issues, you will have to replace the valve cover.

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Comments and Suggestions:
Wim Comments: Hi there, my 2009 Cooper S odo 45k has a major oil leak from the pulley side oilseal. The workshop has replaced it already 3 times within 3000 miles. The first two were genuine Mini seals so we tried an alternative aftermarket version Renz, Germany. It was ok for 2000 miles but recently it started leaking again. The crankshaft surface seems ok, no signs of damage.

Any suggestions?

Thanks for your reply in advance.
November 27, 2016
  Followup from the Pelican Staff: If they don't get the seal in right the first time, it will leak. It might be worth asking if they have the MINI tool to use when installing. - Nick at Pelican Parts  
Jeffy Comments: On my r56 the oil filter housing gasket is leaking verified do I need to put the front end in service mode to change gasket or is there enough room.
November 27, 2016
  Followup from the Pelican Staff: If will be much easier if you do. - Nick at Pelican Parts  
NursePhil Comments: I have a 2010 base model Cooper. I have noticed a slight leak from the valve cover which I can repair. I threw a code: #3 piston misfire. Checked the coil pack and swapped it to the #1 position. Reset the OBD and drove it until the same code popped again. A local mechanic I know told me it was probably oil leak getting into the spark plug because the #3 plug was fouled with oil.

My question is: Do I need to replace more than the valve cover set? Should I replace the valve seals? The job starts to get much bigger with more seals to replace.
September 12, 2016
  Followup from the Pelican Staff: If the coil boot is oil fouled, I would replace the coil. As the insulator may allow voltage to leak under load. So valve cover, engine oil change (for misfire) and the coil with oil on it.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Simonrw Comments: Hi. We have a 2009 cooper S which has an oil leak. Not too seriuos. It also developed a cooling problem which, using your excellant articles, we diagnosed as being the water pump. We removed the water pump and the vehicle has been standing for 2 days. I now notice a large pool of oil under the water pump area. The oil is dark and does not appear to have water mixed with it. Any suggestions?
August 11, 2016
  Followup from the Pelican Staff: Could be a crank seal leak. I would look for signs of the leak on the engine. Look for a clean we spot, that will likely be the source. - Nick at Pelican Parts  
brooklyn Comments: I am looking to buy a mini ONE 2007 and the person who did a look over the car has said that there is Oil leak in engine and power steering pump area, should I steer well clear of this car or do you think it is worth a look into. I am a student so I cant afford to own a car that has to be fixed up a lot so I would really really appreciate your advice. is this the kind of thing I can fix up painlessly or is it going to cost me a lot of money because I cant afford that. a quick reply would be more than appreciated as it goes up for sale soon and I need to make a decision, what do you think, as I said any advice is really more than appreciated!!??
July 31, 2016
  Followup from the Pelican Staff: It depends on if it is simple gasket or something more complicated to repair. Some leaks are fixed easily. I would get an exact location of the leak and repair estimate. - Nick at Pelican Parts  
doug Comments: I have a 2007 mini in which i just put in a new engine. It ran fine last fall the first 2000 miles and I put it away for winter. Started driving again on June 1 and within a week notice oil leaking out of valve cover. There is a lot of oil in plug one on left as you look at engine and in the center bolt cavity on the left. I took valve cover off. cleaned all the gaskets and put back on using gasket seal. It still leaked in the same areas. Does any one have a cure for me.
June 20, 2016
  Followup from the Pelican Staff: Remove the gasket, check if the valve cover is cracked or warped. If not, replace the gasket with new. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
YASIR Comments: Hi , I have 2010 Mini Cooper S R56 and noticed that light green/ transparent oil not very greasy or any smell seep only when i park my car over night same as shown in your firgure #3. Can you please help me to know the aprroximate cost and what is this leak and what action needs to be taken to stop it. I am exteremly worried whether it is safe to drive my car ????
I also evident oil at timing cover at front sump.
May 26, 2016
  Followup from the Pelican Staff: It's impossible for me to say. i can't see the leak clear enough in a photo. Someone needs to follow the leak to the source. Look for a clean path from fresh oil. - Nick at Pelican Parts  
Ian Johanson Comments: Your post was a great help to me. It is detailed enough that I could understand it even though I don't know much about cars and will probably end up taking my car to a shop to get it fixed. Anyway, I appreciate you going through every step and providing pictures of what I should see. Without those, I would have been hopelessly lost.
January 7, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
VTMini Comments: Regarding the crankshaft seal in Figure 6, what part is this for an R56? I am confused by their being front and rear seals available on your site, is this front or rear, or something else completely, thanks! Looks like I have this leak.
October 28, 2015
  Followup from the Pelican Staff: Front I believe refers to the crankshaft pulley side. To be sure, Give our parts specialists a call at 1-310-626-8765 - Nick at Pelican Parts  

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