Four problems related to timing tensioner have been reported for the 2010 Mini Cooper S. The most recently reported issues are listed below.
The timing chain tensioner came loose causing an oil leak and the timing chain to slip/skip which in turn caused damage to the motor and now my car needs a new timing chain & new motor which is costing around $9k. This car only has 35k miles on it & this should not have happened! I was driving on the freeway when all my oil leaked out, causing lights to flash & loud noises. Once pulled over to a gas station and found all the oil was gone, a mechanic there noticed the tensioner coming out, tightened it, then refilled the oil. The car held the oil at this point but then the car would not start. After towing it to a shop, they saw that it would need a new timing chain but didn't want to do a full break down of the car since it is very involved and there could be motor issues so he suggested I contact Mini USA & a Mini dealership. The dealership said they had to have it there to determine the issue & see if the manufacturer would cover the costs. So I towed the car again to a Mini dealership & they said it needs a new motor since the valves were damaged also. After sending this info to Mini USA (the manufacturer), they reported to me that they would pay $4k of the $9k in costs (not even half). Getting advise from a lawyer, this entire issue should be covered by the manufacturer and I already paid too much just by having it towed twice when this is a flaw in the car. The car only has 35k miles & this tensioner should not have come loose in the 1st place causing all this damage. In the end, I am still fighting with Mini USA (after being without my car for almost 4 weeks) to cover all costs of repair for this and asking that this be reported as a "known issue" on the TSB so other people do not have the same problem I am having!! I have attached the email I got from seattle Mini for the diagnosis to give you an idea of what they see happened!.
At about 42000 miles, I started to notice a rattle coming from the engine when the engine was first started. The rattle was most noticeable between 2000 and 3000 rpm. This rattle also coincided with the weather turning colder. The rattle continued to worsen over time, an oil leak developed, and the check engine light eventually came on. After searching the internet and calling my Mini dealership, I determined that the timing chain tensioner was most likely at fault. I ordered the part and replaced it myself. During the process of replacing the tensioner, I found that the old tensioner was loose in its socket. After replacing the part, the engine ran smoothly and continues to run smoothly.
We were driving the car at 20 mph and the check engine light came on. We pulled over to the side of the road and did not note any problems. We then drove directly to the Mini dealership nearby and they said the head gasket seal was broken a leaking oil. Also they said the timing chain and belt tensioner needed to be replaced as they were loose. No repairs were ever performed on these parts. It was noted that there was build up in the oil lines to the turbo causing it to seize up and needed to be replaced. Total costs were $3,000 for parts and labor.
Engine experience rapid oil loss which coated underside of vehicle including tires. When the brakes were applied the vehicle became unstable but I was able to avoid a crash. While pulling to the side of the highway the oil light came on. The vehicle was towed to a mechanic. He reported that a fastener on the cam chain tensioner had become loose which caused the leak. That part had never been modified or service. There was no leak when I began my commute. The problem occurred in only a few miles. Searching online forums indicates that this is not an isolated incident.