Technical Q&A
Article Richard Simonds
Aftermarket wheel finishes
Q
I have an issue with the wheels on my 2008 SL550; they are Mandrus Millennium Hyper Silver with the mirror cut lip. The spokes appear to be clear-coated and are fine. However, the lip has some staining. I have tried to clean them with several products including P21S, Simichrome, and Mothers Mag & Aluminum Polish with little success. Do you have any suggestions?
A
For its own alloy wheels, Mercedes-Benz USA issues information on refinishing wheels to its dealers and authorized refinishers. Because your wheels are made by Mandrus, your best option would be to contact Mandrus Wheels directly: The company advertises in The Star magazine and can be contacted at 1.888.784.1865 or www.mandruswheels.com.
Gremlins in the gauges
Q
I have a 2007 ML350 with 114,000 miles; it has an instrument cluster problem that my mechanic can’t diagnose. I’ll be driving along and the instrument lights flash and the collision warning buzzers start sounding off; as abruptly as it comes, it goes away. After this happens, cruise control stops working; restarting the car restores it. He called the Mercedes-Benz dealer and they told him to replace the instrument cluster ($1,600 for the part alone) but couldn’t say for sure if that would fix the problem. So far, this has never left me stranded; it is just annoying and inconvenient when I want to use cruise control. Nonetheless it’s a major problem because I could never sell the car in this condition. Do you know what could be causing this? One possible clue: The car suffered a front-end collision last summer, prior to all of this happening. But my mechanic checked, and found no chafed wires or other issues.
A
First, of all, have your technician reprogram the electronic-control modules. After that collision, the electronic-control modules could be getting unrecognizable feedback; reprogramming them will typically fix the gremlins. If this does not remedy the problem – and your technician determines that the instrument cluster needs to be replaced – my dealer technical resource said that it doesn’t have to be replaced; it can be rebuilt by Palo Alto Speedometer. Call 650.323.0243 for pricing and details. In models built between the late 1990s to the early 2000s, the instrument clusters were a complete module and the individual components were not repairable: Replacement ran from $1,400-$1,700 – each; it was all or nothing.
Battery discharging issues
Q
I am a longstanding member of MBCA and need help with my 2005 W211 E320 CDI, which has about 106,000 miles on it. It is completely unreliable and the dealership can’t find the problem. Occasionally, when I try to start the car in the morning, I get absolutely no response when I turn the key to the start position, indicating that the battery has absolutely no power. I should mention that I have never gotten the red-warning notice (icon of a battery, reading “Visit workshop”), which would indicate a problem with the charger or voltage regulator. Since nearly new, it has had a problem with the rear batteries discharging – one at a time – down to 3 or 4 volts overnight. In 12 years, I’ve replaced the battery on an average of once a year, but every few months the car refuses to start – usually overnight. When I get in the car, the interior lights don’t go on and often the clock has stopped working. Roadside Assistance will come and charge the battery, but with the battery discharged down to 4, 3 or 2 volts, the battery is damaged, and when this happens a second time, Roadside Assistance replaces the battery. I enjoy the car and don’t want to replace it, but this all means I can’t use it as dependable transportation. Do you have any knowledge of this problem with W211 models? Do you have any suggestions?
A
My technical resource, the shop foreman at a local Mercedes-Benz dealership, offers the following suggestions. I hope they help you resolve the problem and get many more years driving your 2005 E320 CDI.
“This problem should not be too difficult to solve. The first thing that must be done is to measure the current draw at rest with all doors closed. This vehicle should have no more than a 20ma draw after one hour. I would expect your draw to be closer to 2 amps or higher given the rate of discharge. Once the current draw is confirmed, the fun begins. There are some known problem areas to check first: The lower control panel that controls the power-opening compartment for the CD player just below the head unit, which is known to keep the CAN (Controller Area Network) bus awake. Does the compartment function correctly? If it intermittently does not open or close this could be a clue. Another known problem component is the audio gateway. We have seen several of these causing excessive current draws. Due to the complexity of these systems, I recommend seeing a Mercedes-Benz dealership as opposed to an independent shop. I would also recommend speaking directly with their shop foreman so the job gets assigned to a technician who is knowledgeable about trouble-shooting the electronic circuits on cars of this period.” In addition, the experience from another owner of a 2005 Mercedes-Benz suggests that the charging regulator be checked at the same time. During this period, Daimler-Benz was sourcing this component from a supplier other than Bosch and there was a service memo issued when these components started to fail.
Types of automotive paints
Q
I know there was a thread about this a few years back where many said, “all auto paint is the same.” Well, I just bought some Quixx System scratch remover for my Toyota SUV. In the instructions, it said it was “not for use on a nano paint job, or ceramic clear coat, such as on all 2010 or later Mercedes-Benz cars and some earlier Mercedes with the letter “C” as a suffix to the color code.” As I hadn’t intended to use this scratch removal system on either of my Mercedes vehicles, this warning causes me no concern. But this warning is the first and only claim I have seen that at least some Mercedes-Benz paint is different. Does anybody know what gives here?
A
Mercedes-Benz has been moving from paints with volatile organic compounds to water-based paints covered with clear coat. All manufacturers have been making these changes for many years now. However, working with major German paint companies, Mercedes-Benz has refined the quality of its paints and clear-coatings so that they look good and are durable. So, the answer to your question is yes and no. Mercedes-Benz paints are similar to those used by other manufacturers, but with proprietary improvements in materials and compounds. If you want to know what is needed for your specific model, I suggest finding a Mercedes-Benz certified collision center for the details about caring for your paint. Visit www.mbusa.com, scroll to the bottom of the page to “Shopping Tools” and click on “Find a Dealer.” From there, click on “Certified Collision Centers” and click on the state you are in to get a listing of all certified collision centers in your state.