OK . . . I've created another crazy DIY video on how you can very easily and in ten minutes, check your V-6 powered SLK Roadster for a potential worn Balance Shaft Sprocket and/or stretched Timing Chain. This is quite easy to do yourself and will buy you a boatload of peace of mind. Because I just did this myself, I've decided to keep my Blue Mickey a 2005 SLK 350 for the long haul 
Keep in mind, the round stamp you are lining up in the Camshaft Position Sensor holes are not located on the center of the Camshaft Sprocket, but are actually located radially from the center, close to the edge. So, once you've lined up the stamp in the hole on the driver's side intake Camshaft Hole, look at the passenger side hole. If this stamp is well-centered in the hole, you can relax . . . you do not have a stretched Timing Chain or worse . . . you do not have a worn Balance Shaft Sprocket which requires removing the engine to replace. This is due to the fact that there is a bolt under the Flywheel which must be removed to do the job. This is about a five to six thousand dollar repair to have Mercedes perform.
If on the other hand, you see that this stamp is not centered in the hole, but is actually hanging low in the hole, sadly you likely have a worn balance shaft sprocket I believe you can insert a camera down inside the engine to confirm the balance shaft sprocket is in fact the culprit and not simply a stretched timing chain. Keep in mind, a stretched timing chain code on your Reader may also really indicate a bad Balance Shaft Sprocket as the net effect of this, is similar to a stretched timing chain. I would confirm the Balance Shaft Sprocket is indeed bad before going though the trouble of removing the engine. I also believe but am not positive, you can replace the timing chain with the engine in the car.
It is also a good idea to do this check for any potential Mercedes purchase which uses these V-6 engines produced between 2005 and 2008 as it affects models other than the SLK Roadsters as well. I would advise purchasing two new O Rings before doing the job, they are about 75 cents each. I hope this video is useful and takes some of the mystery away from the woes of the lurking Balance Shaft Sprocket issues on these V-6 powered Mercedes from 2005 to 2008.
Keep in mind, the round stamp you are lining up in the Camshaft Position Sensor holes are not located on the center of the Camshaft Sprocket, but are actually located radially from the center, close to the edge. So, once you've lined up the stamp in the hole on the driver's side intake Camshaft Hole, look at the passenger side hole. If this stamp is well-centered in the hole, you can relax . . . you do not have a stretched Timing Chain or worse . . . you do not have a worn Balance Shaft Sprocket which requires removing the engine to replace. This is due to the fact that there is a bolt under the Flywheel which must be removed to do the job. This is about a five to six thousand dollar repair to have Mercedes perform.
If on the other hand, you see that this stamp is not centered in the hole, but is actually hanging low in the hole, sadly you likely have a worn balance shaft sprocket
I believe you can insert a camera down inside the engine to confirm the balance shaft sprocket is in fact the culprit and not simply a stretched timing chain. Keep in mind, a stretched timing chain code on your Reader may also really indicate a bad Balance Shaft Sprocket as the net effect of this, is similar to a stretched timing chain. I would confirm the Balance Shaft Sprocket is indeed bad before going though the trouble of removing the engine. I also believe but am not positive, you can replace the timing chain with the engine in the car.It is also a good idea to do this check for any potential Mercedes purchase which uses these V-6 engines produced between 2005 and 2008 as it affects models other than the SLK Roadsters as well. I would advise purchasing two new O Rings before doing the job, they are about 75 cents each. I hope this video is useful and takes some of the mystery away from the woes of the lurking Balance Shaft Sprocket issues on these V-6 powered Mercedes from 2005 to 2008.
