Q: Starting problems with a 2012 Mercedes ml350 blue tech

It takes a lot of battery to turn a diesel, so if your battery voltage is not 12.6, you need to charge or replace the battery. I don’t recommend jump starting the car, because the electrical system may develop problems from the power surges that inevitably result. When you mention the "starter" fuse, I presume you mean the glow plug fuse, which is powered up by the glow plug relay and the engine’s controller. It’s not really possible to troubleshoot these pieces without the appropriate diagnostic equipment, so your best bet is to have this thing checked out by a technician equipped with a Mercedes Specific scanner. The generic scanners won’t really do the trick in this case. As for your black sludge, that may not be as bad as it sounds. The oil in diesels turns black very quickly even when fresh. It’s just a by product of the diesel combustion. That said, I recommend you contact Your Mechanic to have a technician come out to your home or office to check out your Mercedes and let you know what it will take too fix it.