If there's a click, but nothing else, then the starter solenoid is kicking into postion but not able to turn... sticking / binding due to mis-matched coefficients of thermal expansion or solenoid bearing wear. If there's not even a click sound, then the solenoid isn't kicking into position at all... which may mean a loose wire somewhere between ignition switch and starter solenoid. I had the click but no turn-over problem on my '65 Chevy Pickup... everytime I stopped for gas it wouldn't restart for awhile but it clicked every time. Once I was checking my oil/water while refueling and it started right up when I was done refueling... I though "luck"... but opened the hood again the next time I fueled up, and it started right away again. I kept the hood shut and it wouldn't start for about 10 minutes. Turned out that the heat-shield between my exhaust and starter nearest the solenoid had fallen away ... I repositioned and secured it properly and problem went away (to this day and that happened 5 years ago). Opening the hood allowed convection cooling to cool the solenoid (hot engine heat rises, pulling colder air up past the solenoid / exhuast thru the opening of the hood. If the hood remained closed, not enough convection was generated while I refueled.... hence having to wait another 10 minutes or so... depending on the ambiant air temperature.
Longtooth
67 250SL US #113-043-10-002163
The 6% Club - Best of the Best
'02 SL500 Sport