Q: My 2001 c320 has an intermittent starting problem. I turn the key to start the car and nothing. There is no engine turn over. All

A YourMechanic no start diagnostic on the problem you have written in about involves first determining whether or not full battery voltage is reaching the starter motor itself. If not, then the circuit has to be traced from the battery onward, through the wiring, fuses, relay, ignition switch and so forth until the break in the circuit is found. On the other hand, if it is determined that full battery voltage (i.e., no voltage drop due to high resistance in circuit) is reaching the starter motor, that means you need a new starter. In the latter case, by the way, sometimes starter motors develop a "bad spot" on the armature and thus if you use a rubber mallet and strike the motor (the motor, not the solenoid housing), you can sometimes get the starter to work as the armature "jumps" past the bad spot. If the rubber mallet trick does work, of course, that is a further indication that the "intermittent" fault is within the starter itself. Do not use metal tools around the starter, by the way, as you can cause a short circuit to ground if you touch the exposed hot terminals causing damage and personal injury. If you would like a certified mobile mechanic to professionally diagnose and repair your no start problem, by all means please follow up with YourMechanic.