The sound you hear is that of the solenoid swicthing power to the starter, the voltage dropping, the solenoid switching off and the cycle repeating. the reason it repeats is that there is enough current to operate the solenoid but not to turn the starter motor. now 11 volts whilst the starter is in operation is quite good in my experience, which suggests to me that the problem is bad contacts giiving high resistance in the circuit. battery might or might not be OK but all the contacts / terminals need cleaning too.


