Like many members of this forum, the clutch release bearing of my R50 Mini Cooper failed after a relatively short life of only 51387 miles back in March. In what I hope is a unique situation, the crankshaft was found to be excessively worn during the clutch replacement work. Despite having a full MINI approved Dealer service history and an Inspection II carried out as recently as October 2009, BMW Customer Services have paid no interest to the technical implications of this failure because I had the repair work carried out at an independent garage.
As crankshaft play is NOT a checklist item for any of the MINI Service or Inspection activities, this latent wear has occured over a considereable time, and is likely to have been out of specification for many years, perhaps even while the car was still within it's warranty period (axial crankshaft play service limit is 0.3mm, I had many mm of play!)
The pictures below are from actual the crankshaft and thrust bearings removed from my car.
As BMW's Customer Service advisors have been unwaivering from their policy of only considering technical inputs from Approved MINI Dealers, may I suggest that you ask for the axial play of your crankshafts to be checked at the next service; particularly if you have previously had issues with your gearbox or clutch.
Not exactly the "intrinsic quality of the marque" we would hope for from BMW!
Unworn Crankshaft thrust bearing surface:
The good and the bad:
Completely destroyed thrust bearing surface:
Thrust Bearing shell - the good side:
and the bad!
As the crankshaft replacement kit was £580 (GBP) and BMW charge 17 std hours to replace this item, this could be a non-economic repair for some cars!
I'd appreciate any feedback from other members who may have heard of or experienced such extreme engine wear: as I could not find any posts relating to crankshaft wear.
Sorry to here about your problem - this is a new one on me as I have not heard of a crankshaft failure before other than when one has been run without oil !!
I am not sure how you would expect MINI or any other manufacturer to offer assistance for problems found by another garage. If it had been discovered at a MINI garage then there may have been a chance of some Goodwill from the manufacturer but somewhere else = no chance.
Also I am not aware that any mass car manufacturer has crankshaft end float as part of it's service schedule.
Hi Snowie, as you can hopefully see from the pictures, this wear was not caused by a lack of lubrication! I firmly believe the root cause was a manufacturing issue with this specific crankshaft. This may have been exasperated by the clutch Release Bearing exerting undue axial pressure.
Despite assertions from BMW Customer Service that "warrantable manufacturing concerns, should they arise, will by their very nature become apparent within the first 24 months of a vehicle’s life" is not necessarily true for failures such as with this crankshaft.
While I fully accept and apprecaite the identification of the issue outside of a MINI approved dealership leads to no application of "goodwill" towards the repair costs; what is not acceptable to me is the lack of interest or concern in the failure of this part or why it occurred. I have also offered to have my car made available for inspection at my local MINI Approved dealer.
The crankshaft is a surcharge item and so is returned to BMW and I have retained the thrust bearing: both are available for inspection and analysis.
I fully appreciate and expect parts of a vehicle to wear and need replacement through it’s working lifetime. However, I did not expect the crankshaft to have a lifetime that was shorter than the front brake discs on my MINI!
Last edited by rab-67; Apr 26th, 2010 at 04:19 PM.
The wear to the crankshaft is not a manufacturing defect, if you had owned the vehicle from new, then you would know how the clutch would have been treated through it's life, there are two main factors to this kind of excessive wear. All of us should keep in mind that the principle cause of excessive crankshaft end float is the manual gearbox and clutch, the pressure of the de-clutching action is what serves to drive the crankshaft forward each time a gear change is made, this wear pressure is especially compounded by those who sit in gear holding the clutch while waiting for a traffic light or when stopped for any period of time, this is in turn compounded by the fact that the engine is idling at that time and oil pressure is at its lowest thus increasing the opportunity for wear to occur, even further compounded by a low oil level too.
Performance Powered By Thought. Engineered Horsepower.
Hi Czar, apprecaite your inputs. According to the Clevite "Engine bearing failure analysis guide" (a very interesting publication) http://engineparts.com/publications/CL77-3-402.pdf the external overload you mention is only one of three of the most common causes of Premature Thrust Bearing Failure
CAUSES OF FAILURE
Aside from the obvious causes, such as dirt contamination and misassembly, there are only three common factors that generally cause thrust bearing failures. These are:
• Poor crankshaft surface finish
• External overloading
With the exception of the first six months of my car's life as a dealer demonstrator, I've owned this car from new. I don't "ride" the clutch nor sit with the clutch engaged at traffic lights. Like the majority of members in this forum, my car is pampered; well maintained (including regular oil checks and top-ups) and looks "like new."
Indeed the independent garage where I had the work done had only seen one crankshaft in a worse state as the one that came out of my MINI, and that was from a Vauxhall (Opel) Astra that was "running" with the same oil as it had left the factory with ten years earlier!
If driving style was the root cause of the extreme wear on the crankshaft and thrust bearings, surely there would be other known examples of such wear known in our community?
Even taking the extreme view that I have the worst driving style out of the whole MINI owners’ community; then surely I would have experienced equally gross failures in the engine, clutch or transmission in other vehicles I have owned in my 25+ years of driving? Thankfully, there is no such litany of destroyed engines or bank-balance destroying repair bills as I have just paid out on my MINI.
The garage that carried out the repair believed the root cause of this wear was a manufacturing issue with the crankshaft.
Can you help me understand why you were able to so quickly dismiss the possibility that a manufacturing issue could have existed on the crankshaft removed from my MINI?
As I clearly stated not only is this from external pressure force wear, this has also been subject at some point to poor oil feed, this could be for a number of reasons, and you may never find the exact cause, now although you have almost owned the car from new and pampered it like it is your baby, you cannot rule out misuse from the first owner, this being a demonstrator!
Can you for sure rule out, any low oil levels or even poor oil pressure, what about debris from a component, all possible before you purchased the car! It takes but a moment to destroy the surface face of the bearing, once this has happened, then it's too late, and over time, this amount of wear is not uncommon, once the finished face has been affected then rapid wear will occur.
I have been in the Racing industry all my life, from boy to man, as well as having 26 working years as, a Race car engineer and engine product development, I have seen more engine component failures, than I care to remember, so from my experience of this, upon looking at your photographic evidence, this is how I came to my conclusion, of the failure, I hope this helps.
Performance Powered By Thought. Engineered Horsepower.
I have to say, from the pictures you have posted, I have to agree with Czar.
I dont think Czar is having a personal attack on your driving or servicing of your MINI, but he has a fundamental point, that part has failed because of excessive pressure on the bearing surface or lack of lubrication (excessive pressure across a bearing surface beats the oils ability to build a film layer between the two surfaces, so the end result in the two cases is the same!) in fact it is quite obvious in one picture there is discolouration from heat build up, heat would only be present if the bearing was overstressed or there was a lack of lubrication... this would not be present if the component just failed because it was too soft, the only likely manufacturing defect to only effect the bearing and the crank.
As Czar said, you dont know the full history of the car... wouldnt be the first time I have seen a new car delivered to the dealer with next to no oil in it (manufacturers like to put the bare min. in, then expect the dealers to top them up FOC at the Pre Delivery Inspection... a litre a car saves them a fortune over several thousand cars!) Demonstrators quite often get an 'edited' PDI, or often completely miss a proper PDI!
But I would also be making bloody sure everything was checked thoroughly while the crank was out, and more importantly, I would be asking why the thrust bearing failed... the crank thrust bearing shows sign of excessive axial thrust in one direction only, the thrust bearing ,which only wears when it is applying an axial thrust in one direction only to the crankshaft via the clutch, failed at a relatively low milage... could be a coincidence, but I dont believe in those!!!
If you are certain it is not a driver issue, which I agree with you, is unlikely as you would have experienced this on other cars you have owned, then I would strongly recommend checking that there is not excessive preload on the clutch release mechanism. The problem you have here is that it may take 50k to wear out the new parts if the original fault is not addressed... by then (if you still own it!) you are unlikely to have any case against the independant that has done the work for you, let alone BMW themselves.
"Allow me to explain... Understeer is when you hit the armco going forwards, Oversteer is when you hit it going backwards!"
Based on the photographs, your bearings were damaged in part by contaminated oil, the evidence is all the pits in the wearing surfaces. This is some of the worst I have seen, but it is not a manufacturing defect.
There are many causes for thrust bearing failure. Looking through this thread I have seen a very similar problem. The problem was due to a clutch arm not fully returning, hence you would not notice it untill a fault occured.
The pictures also tell a story, crank thrust bearings are made out of mild steel, copper coated then white metaled. The white metal is only a couple of thou thick. It appears in this particular case there has been a partial seizure in the clutch return, this of course would cause premature bearing failure.
Once the white metal wears away your left with a couple of microns of copper plating, (won't last five minutes). Once on the metal, excessive heat occurs, (steel on steel) then the remainder of the bearing acts as a cutter.
This is evidenced by your photo of the blue colouring.
I would be most concerned with the root cause, it will be horrible to have all that work done (only to have it destroyed in a few months). Check the clutch release mechanism. (Have this done by a proper mechanic).
We recently ran into the same issue with the thrust face on the crankshaft. Most certainly, sitting at lights with the clutch depressed will exacerbate the issue, but from an engineering standpoint, not enough safety factor was built in. Most manufacturers use double thrust bearings. This gives you twice the load bearing surface. This is a very inexpensive solution albeit after the fact. A small notch for the bearing tang has to be cut in the lower bearing saddle and a new bearing seats fine.
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