We’ve held off on reporting on this issue for the past few months trying to gather as much data as possible before presenting it to readers. After some investigation, we now believe we have a good picture of the issue as well as some real evidence of it. While a cold start problem doesn’t seem to be an entirely widespread phenomenon, there’s little question that there are more than a few of owners dealing with it around the world. The following report is one owner’s experience with it.
The following story was written by new MF Contributor Mike Hansen
For most owners, purchase of the new MINI R56 has been a very positive experience. As first model year cars go, the second generation new MINI has been relatively free of problems. Sure, surfing NAM or MINI2 one will have seen the slew of rattles, or crooked bonnetsÃ¢â‚¬Â¦ and yes there have been a couple transmissions and clutch plates replaced… but all in all, these problems have generally been easy to identify and correct. To be honest, they aren’t outside of the realm of issues associated with the previous generation car, even after five years of production. That is, until now.
Beginning this past spring there has been a common theme popping up in the Faults and Fixes threads on various MINI forums. Specifically, MCS owners complaining about a peculiarly loud engine rattle on start-up. Now the R56 is an “interesting” sounding engine to begin with. The combination of the VANOS system and the direct fuel injection solenoids give the car a very diesel-esque sound at idle. But this is a very different sound altogether.
Generally, owners experiencing this rattle note that the “cold start” aspect has less to do with the ambient temperature as it does with the inactivity of the engine. Usually this rattle occurs during the first start of the day when the engine itself is “cold” and oil has drained into the sump. Appearing to originate along the left side of the head near the cam chain, the rattle is out of synch with the normal cadence of the engine and has a metal on metal tapping quality to it. It seems to decrease with higher RPMs and as the engine warms up to operating temperatures. For most the noise starts off as an infrequent occurrence and only a minor annoyance and many don’t feel the need to bring it to their dealer’s attention. Eventually however, the frequency, duration and sheer volume of the rattle increases.
The noise is a sporadic problem and does not occur with much predictability. It therefore becomes a very difficult thing for owners to present to their dealerships or for Service Technicians to diagnose. Based on the perceived point of origin, most MINI Service Departments who have actually heard the rattle for themselves have logically focused their attention on the cam chain tensioner. Many cam chain pistons have been replaced after fining that they were receiving less than sufficient oil for proper operation. This fix has been documented under MINI Service Bulletin #110207. Unfortunately for most owners, it has only been a temporary fix with the rattle returning in only a few short weeks.
Once the replacement chain tensioner fails, focus usually turns to the head itself. Specifically the hydraulic lifters, valve guides and the VANOS Solenoid. Again the theory is that oil is failing to properly enter the head and operate the valves during cold starts. Several owners have received what equates to a full rebuild of the car’s head in an attempt to diagnose and eliminate the cold start clatter. Some owners have reported the installation of a one-way check valve during the rebuild to keep oil from draining after the engine has been turned off. Unfortunately these too seem to be only a temporary fixes with the engine rattle returning only a short time later.
Ultimately MINI has taken the giant step to replace a handful of engines not only to solve the problem for the owner, but to bring the offending power plants back to MINI for inspection. One would think this would be a sure way to stop the engine rattleÃ¢â‚¬Â¦ but that has not necessarily been the case. At least one owner on MINI2 reports the noise came right back after only a few months of operation following a complete engine and head swap.So is this even a problem? Some owners report being told the cold start rattle is “completely normal” and only a “trait of the engine”. One dealership in the UK has suggested that the cause of the noise is a lack of equalization of pressure within the head by the crankcase vacuum pump causing the pump to vibrate in its journal bearings. The suggested fix was to remove the vacuum pipe during start up. Otherwise the noise was said to be causing no harm and could not be fixed by a replacement part. Again, a trait of the engine design. This is tough pill to swallow for most experiencing the issue. I would argue that a metal-on-metal rattle that goes away with some combination of oil flow and operating temperatures has to be increasing wear and tear on the internals of whatever specific parts generating the noise. For some, merely living with this cold start rattle will not be an acceptable option.
Another theory posted by one R56S owner on the Michigan MINI Motorin’ Club website provides probably one of the best technical discussions on this particular issue. The basis of the theory is that air is getting into the oil circuit operating the hydraulic lifter system causing the valves to open and close out of time and “slam” into the closing ramp of the cam (causing an out-of-time knocking from the head). A decent theory, back up by some good technical know-how (and pictures for us laymen) and the answer provided may even be a simple solution: minimize the valve lash adjustment and use lower viscosity oil. For those experiencing the noise, the recommendation was made not to rev the engine over 2000 RPM until the oil properly fills the circuit and the noise goes away as damage could occur at higher RPM’s. Sounds like a very plausible theory, but time will tell.
So why should anyone care if it’s not effecting their car? Well, speaking from experience, my car did not produce this rattle for the first 5000 miles. When it began, I heard the rattle once or twice during that month. Over a two month period it got worse and worse. Some have noticed the problem within the first 1000 miles of operation while others have yet to hear any noises of any concern. Build date doesn’t seem to be a factor either, as some November and December cars are demonstrating the same cold start engine rattle already.
Mine is one of the engines that is going back to MINI for further inspection. I have been down every road described above to no avail. I will say that my dealer (Northwest MINI) has been more than helpful and has shown their dedication to working with MINI to find some answer to this problem. The bottom line is that the cause and solution to this cold start rattle are still unknown or at least unacknowledged by MINI. Based on what I’ve seen, I believe a full engine replacement will only be a temporary fix and in effect buy time for MINI to come to a more permanent solution. Keep in mind there have been no changes to the 2008 power plant to suggest that this issue will be limited to first-year production cars. So any MCS or Clubman S could theoretically have the potential to develop this rattle on start up.I have my car back now after six weeks in the shop addressing this cold start rattle. With a new engine in place, I am starting my break-in once again. The engine is starting and running fine but I must say my overall confidence level in this car is non-existent right now. I’m about 1/3 of the way through my warranty and have no assurances that the new engine will not develop the same problem over time. In fact, I’m aware that it most likely will. If it’s anything like the original block, it’ll be 5000-8000 before I hear it again… which puts me 2/3rds through my warranty. Like I said, ZERO confidence.Ã¢â‚¬Â¨If you factor in the first attempt to address this cold start rattle (cam chain tensioner replacement) I have been without my car for 2 months out of 11. So 18% of my ownership experience to date has been spent without my new car. I sincerely hope a permanent answer comes sooner vs. later. I for one would like to recapture some of those positive feelings I had towards my MINI just a few short months ago. Ã¢â‚¬Â¨
Clearly there is a lot of speculation by owners as to what’s causing the horrible cold start rattle, if any damage is occurring and what will be done (if anything) to correct the problem. Most currently believe the relationship between the oil, oil pump and ECU should be the next point of focus and that all previous “fixes” have addressed the symptoms, but not the cause of this rattle. As you might recall, the R56 will slow or stop the circulation of certain fluids during start up to speed up the engine warm-up process and conserve energy. But again, this is just owners talking and the expectation is that the MINI engineers will eventually get to the bottom of things. Speaking as a new MINI owner experiencing this problem first-handÃ¢â‚¬Â¦ I for one hope this answer comes sooner rather than later.
Update: Since this story was written last week, we’ve been touch with MINI USA about the issue. While this problem doesn’t seem to be wide-spread (everyone I spoke with were unaware of the issue due to lack of warranty reports), they urge anyone who believes they have an issue to contact their dealer as well as MINI Customer relations. Despite not having first hand knowledge of this particular problem, everyone I spoke with seemed genuinely interesting in resolving any potential issue (whether it be cold start related or anything else) quickly and effectively.