Monday, September 15, 2014

Is a Software Bug Setting MINI Coopers on Fire?

In the summer of 2013, we got a call from the owner of a 2008 MINI Cooper S, an R56 model. She’d gotten in her car to go to work, and her power steering wasn’t working.  We got the car in, and found a burnt steering motor (EPS) and a damaged high power electrical connector.  We replaced the parts, checked the coding, verified that the steering worked, and sent her on her way.  We’ve replaced quite a few steering motors so this one didn’t raise any eyebrows.

A year later the pump failed again.  This time the connector actually melted enough to separate from the steering motor.  When the owner tried to plug it back in the sparks told him to back off.  MINI supplied a new motor and connector under parts warranty, and we changed them.  Once again the steering worked.  We thought it strange that the motor we changed a year ago would fail.

A month later the owner drove the car to dinner and parked it for the night at 8PM.  Twelve hours later – at 8 on a Sunday morning – a neighbor spotted smoke coming from the MINI’s cowl.  The owner opened the hood to find a fire above the new EPS steering motor.  It seemed like it had gotten hot enough to start a fire.  What was going on?

The car was examined by two forensic investigators, each representing insurance companies that might be involved in settling the claim.  The first investigator’s job was to learn whether the EPS started the fire, and if so, if there was a workmanship error in its fitment. There was no error found.  Installation of the motor is simple and straightforward.  

The second investigator built on the first investigator’s findings, in an effort to further understand the cause of the fire.  Both investigators agreed that the fire was started by an overheated EPS unit.  The question was, why would the EPS overheat and start a fire after sitting overnight?  There is no circumstance where the power steering motor should activate in a parked and locked car, 11 hours after it was parked for the night.

The EPS just sits there when the car is parked.  It draws no power at rest, and should have been at ambient temperature by late that night.

A conversation with the owner revealed that this was a pattern of failure.  The steering never failed when the car was in use.  Instead, the motors burned out while the car was parked.  The complaint was, “no steering when I got in the car,” as opposed to, “the power steering quit while I was driving.”

We began to wonder how many other MINI owners had experienced similar failures.  We searched our own service database and realized most MINI power steering failures we’d seen were “in the morning” as opposed to “while driving.” An Internet search raised quite a few more possibilities.  And we read of some troubling and unexplained fires in parked cars.

The investigation has ended – for now at least – with no definite answer.  The car’s insurance will pay off, and the owner will get a new car.  We were never able to determine what woke the car’s electronics up and caused it to start steering till it caught fire.

We were able to determine that the car slept most of the night undisturbed.  An analysis of the charge in the battery told us how much energy the steering motor had absorbed.  A calculation told us how rapidly that had to occur, to build enough heat to start a fire.  Another calculation told us how fast the steering could heat up, given the limitations of fuses and wiring.  We determined that it woke up and started trying to steer 30 minutes to an hour before catching fire.

That raised an interesting possibility.  Could the car have been woken up by radio signals, and come to life in an unexpected and destructive way?  We know the pushbutton entry system can do more than unlock the car.  So can the radio link that the BMW/MINI service and concierge people use.  Might something have come into the car through those channels?  We don’t know.  It’s an idea, but without more evidence we are stumped.

What’s your experience?  Do you know of a MINI that caught fire while parked, with no good explanation?

Robison Service has provided independent service, repair, and restoration for BMW and MINI owners all over New England for over 25 years. Our company is an authorized Bosch Car Service Center. We also service Mercedes, Jaguar, Land Rover, Porsche, and Rolls Royce and Bentley motorcars. We have flatbed transport throughout the region. We also offer pickup and delivery for cars in  Springfield, Wilbraham, Longmeadow, Agawam, Westfield, Northampton, and Amherst.

Monday, September 8, 2014

Fixing Grinding Noises in Mercedes Transmisisons

Do you have a grinding noise in your 2007-2013 Mercedes 4Matic gearbox? Do you hear a grind that starts at low speed and increases as the car speeds up until it’s so loud you’re afraid to drive it? Many people confuse the noise with wheel bearing failure, but it’s not. The 2008 and new C-Class 4Matics are prone to this same failure. S550 and C300 4Matics are the most problematic. If you’ve got either of those models, read on.

We’ve seen several W221 S-Class Mercedes 4Matics with noisy transmission / transfer case assemblies, and we’re thinking this may become more common as the vehicles age.  The cars we’re seeing have 60-90,000 miles on their odometers when they start grinding.

Our most recent client came to us after the local Benz dealer told him he needed a new transmission, because Mercedes didn’t want them making internal repairs.  He thought $6,000-some was a lot of money for a bad bearing and he asked if we could help.

Of course we said yes.  Lead tech Danny Ferrari in our Mercedes shop removed the transmission and tore it down, whereupon the failure was obvious.  The bearings had failed. The ones that carry the transfer case shafts and take the load from the driveshaft had totally come apart.  It seemed like an easy fix, but Mercedes does not sell internal parts and they build this gearbox in-house.

We have spent the time to locate sources of original quality repair parts overseas, and we’re now able to fix these formerly unserviceable units. We can generally save you a few thousand dollars over the cost of a dealer exchange part.

Our shop can perform any service or repair on these fine cars, including transmission services. However, there’s no preventative maintenance we know of that will head off this bearing failure. It may be that the load on these bearings is just too much for their size, or there may be another cause.

If you've got an older Benz, look to us for transmission fluid flushes, filters, repairs to the sensor plate, and repair of leaking electrical feed-through connectors.  The older Mercedes transmissions are showing more problems because the years and miles are piling up, but we can fix anything that happens to them.

From what we can see the repaired transmissions will last as long as the originals, and repair takes less than a week, start to finish, for most units.  J E Robison Service is a Bosch Car Service specialist in Springfield, MA.  Find us at 347 Page Boulevard, in the Springfield Auto Complex, in Springfield, MA 01104.

Robison Service has provided independent service, repair, and restoration for Mercedes Benz owners all over New England for over 25 years. We also service BMW, MINI, Jaguar, Land Rover, Porsche, and Rolls Royce and Bentley motorcars. We have flatbed transport all over the region. We also offer pickup and delivery for cars in  Springfield, Wilbraham, Longmeadow, Agawam, Westfield, Northampton, and Amherst.

Visit us online at or call 413-785-1665.

(c) 2014 John Elder Robison