ML350 Suspected Balance Shaft Issue
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Joined: Feb 2014
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ML350
ML350 Suspected Balance Shaft Issue
Hi, I'm new here with this being my first post, however, I have been reading the threads regarding the "balance shaft" issues for quite some time. I would appreciate any feedback I can get regarding not only my suspected balance shaft issue but also my MB dealership and Corporate experience. I'll try and summarize the best I can.
So my wife fell in love with a used 2006 ML350 we purchased from a Lexus dealership approximately 3 years ago with 60k. For the most part I have to say it's been a good car to us. About a year and a half ago the CEL came on and the car suddenly started misfiring. If you turned it off and waited a second before restarting the misfire would go away but the CEL would stay on. We took it to an independent Mercedes mechanic who said it was misfiring on #1. The symptoms went away and he reset the CEL. A few months later it returned and was now a misfire on #3. My mechanic installed a new coil and checked all the affiliated wiring. The misfire ended up shifting to another cylinder. We both agreed it was not a coil and checked other options. Once again, it went undiagnosed but ultimately disappeared. The symptoms and light didn't return until about six months ago. Now the misfire doesn't go away if you turn off the engine, however, if the car sits for a few days it will run fine for about 15 miles then the light comes on and it drops to about half power.
I read all the forums and with a little bit of mechanical background myself we tried to narrow it down by checking camshaft sensors, fuel system, coils and wiring, etc. I took it to 2 different mechanics and they are all baffled and leaning toward the balance shaft.
I called MB USA and explained my issue. I explained my knowledge of the balance shaft issue and found them very deceptive over the phone. They wouldn't answer any questions or concerns and told me I needed to take it to an authorized dealer for a diagnosis before they could open a case. I can understand this point so I took it to San Francisco Mercedes service center for a diagnosis. I tried to talk to the service tech regarding my concerns and the previous work performed and was told "parts wear out" in regards to the balance shaft. The service tech was also very evasive and wouldn't answer any questions about the balance shaft. I figured at this point I would just wait for their diagnosis.
He called me today and said he had good news, " it's not the balance shaft, you need a valve job for $5,900". I asked 2 simple questions. How did you rule out the balance shaft and what steps were taken to diagnose a valve job is needed? He wouldn't answer either question except by telling me they "conducted a comprehensive diagnosis" and he would call me back with more info. He never called back.
What I didn't tell him is a compression test was done and all cylinders were within spec, each spark plug was checked and all were burning normal, the car doesn't burn any excessive oil between changes, and there's no burnt oil coming from the exhaust. I can't see in any way how a valve job would repair a misfire when there is no objective symptoms. My thought is they can repair the balance shaft easily if the heads are removed and by convincing me to pay for a valve job they can repair the balance shaft for basically nothing and it doesn't count as a balance shaft repair.
Everyone I have talked to at MB from corporate to the dealership is dancing around the issue at hand and nobody will answer any questions. Does anyone see how a valve job would fix the symptoms present? Has anyone had better experiences with another MB dealership in the San Francisco Bay area? Any thoughts or suggestions at this point would be greatly appreciated. We are making payments on a car we haven't driven for months and can't afford the 8k repair price I've been quoted for a balance shaft repair on a car only worth 15k now.
So my wife fell in love with a used 2006 ML350 we purchased from a Lexus dealership approximately 3 years ago with 60k. For the most part I have to say it's been a good car to us. About a year and a half ago the CEL came on and the car suddenly started misfiring. If you turned it off and waited a second before restarting the misfire would go away but the CEL would stay on. We took it to an independent Mercedes mechanic who said it was misfiring on #1. The symptoms went away and he reset the CEL. A few months later it returned and was now a misfire on #3. My mechanic installed a new coil and checked all the affiliated wiring. The misfire ended up shifting to another cylinder. We both agreed it was not a coil and checked other options. Once again, it went undiagnosed but ultimately disappeared. The symptoms and light didn't return until about six months ago. Now the misfire doesn't go away if you turn off the engine, however, if the car sits for a few days it will run fine for about 15 miles then the light comes on and it drops to about half power.
I read all the forums and with a little bit of mechanical background myself we tried to narrow it down by checking camshaft sensors, fuel system, coils and wiring, etc. I took it to 2 different mechanics and they are all baffled and leaning toward the balance shaft.
I called MB USA and explained my issue. I explained my knowledge of the balance shaft issue and found them very deceptive over the phone. They wouldn't answer any questions or concerns and told me I needed to take it to an authorized dealer for a diagnosis before they could open a case. I can understand this point so I took it to San Francisco Mercedes service center for a diagnosis. I tried to talk to the service tech regarding my concerns and the previous work performed and was told "parts wear out" in regards to the balance shaft. The service tech was also very evasive and wouldn't answer any questions about the balance shaft. I figured at this point I would just wait for their diagnosis.
He called me today and said he had good news, " it's not the balance shaft, you need a valve job for $5,900". I asked 2 simple questions. How did you rule out the balance shaft and what steps were taken to diagnose a valve job is needed? He wouldn't answer either question except by telling me they "conducted a comprehensive diagnosis" and he would call me back with more info. He never called back.
What I didn't tell him is a compression test was done and all cylinders were within spec, each spark plug was checked and all were burning normal, the car doesn't burn any excessive oil between changes, and there's no burnt oil coming from the exhaust. I can't see in any way how a valve job would repair a misfire when there is no objective symptoms. My thought is they can repair the balance shaft easily if the heads are removed and by convincing me to pay for a valve job they can repair the balance shaft for basically nothing and it doesn't count as a balance shaft repair.
Everyone I have talked to at MB from corporate to the dealership is dancing around the issue at hand and nobody will answer any questions. Does anyone see how a valve job would fix the symptoms present? Has anyone had better experiences with another MB dealership in the San Francisco Bay area? Any thoughts or suggestions at this point would be greatly appreciated. We are making payments on a car we haven't driven for months and can't afford the 8k repair price I've been quoted for a balance shaft repair on a car only worth 15k now.
Thread Starter
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Joined: Feb 2014
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ML350
Here's the reply from the dealer today. Does this make sense to anyone? I still cant see how a valve would only cause a misfire once the CEL is on. Here's the codes they said they got from the car 0060 0654 0644 If that helps. I'm going to try and attach the photos too. I know newbies don't usually get much love on forums but any advise would really be appreciated.
ATTACHED ARE PRINT SCREEN SHOTS FROM FAULT COUNTER CYL # 1 WITH ENGINE RUNNING, COMPRESSION TEST SPECS AND ACTUAL COMPRESSION TEST THAT SHOWS CYL # 1 HAS A 24rpm SPEED DIFFERENCE (MAX RPM DIFFERENCE ALLOWED BY MANUFATURER IS 28rpm) COMPARED TO ALL OTHER GOOD CYLINDERS. ALSO ATTACHED PICS FROM LEAK DOWN TEST THAT SHOWS CYL # 1 IS SLIGHTLY HIGHER THEN CYL # 3 (RANDOM PICKED CYL # 3 SINCE THAT CYL WAS A GOOD COMPRESSION WITH GOOD LEAK DOWN)
ALSO PICS ATTACHED FROM THE BORE SCOPE EVALUATION WICH REVEALES A POSSIBLE BURNT EXH VALVE FROM # 1 CYL THAT POSSIBLY CAUSES THE MISFIRE.
IN THE PROCESS OF DIAGNOSING, THE IGN COILS WERE INTER CHANGED AND ALSO THE SPARK PLUGS. THE MISFIRE STILL WAS DETECTED ON CYL # 1 WITH THE IGN COMPONENTS INTER CHANGED.
AT THIS POINT, IN ORDER VERIFY THAT CYL # 1 HAS A MECHANICAL ISSUE CAUSING THE MISFIRE, THE NEXT AND ONLY STEP WOULD BE TO REMOVE THE CYL HEAD AND INSPECT THE # 1 CYL EXHAUST VALVE SEATS AND EVALUATE.
ATTACHED ARE PRINT SCREEN SHOTS FROM FAULT COUNTER CYL # 1 WITH ENGINE RUNNING, COMPRESSION TEST SPECS AND ACTUAL COMPRESSION TEST THAT SHOWS CYL # 1 HAS A 24rpm SPEED DIFFERENCE (MAX RPM DIFFERENCE ALLOWED BY MANUFATURER IS 28rpm) COMPARED TO ALL OTHER GOOD CYLINDERS. ALSO ATTACHED PICS FROM LEAK DOWN TEST THAT SHOWS CYL # 1 IS SLIGHTLY HIGHER THEN CYL # 3 (RANDOM PICKED CYL # 3 SINCE THAT CYL WAS A GOOD COMPRESSION WITH GOOD LEAK DOWN)
ALSO PICS ATTACHED FROM THE BORE SCOPE EVALUATION WICH REVEALES A POSSIBLE BURNT EXH VALVE FROM # 1 CYL THAT POSSIBLY CAUSES THE MISFIRE.
IN THE PROCESS OF DIAGNOSING, THE IGN COILS WERE INTER CHANGED AND ALSO THE SPARK PLUGS. THE MISFIRE STILL WAS DETECTED ON CYL # 1 WITH THE IGN COMPONENTS INTER CHANGED.
AT THIS POINT, IN ORDER VERIFY THAT CYL # 1 HAS A MECHANICAL ISSUE CAUSING THE MISFIRE, THE NEXT AND ONLY STEP WOULD BE TO REMOVE THE CYL HEAD AND INSPECT THE # 1 CYL EXHAUST VALVE SEATS AND EVALUATE.
