Goodness, the reports here about the 94 and 95 C220's and 280's are simply breathtaking. I bought a 1994 C280 last weekend. Since that time it has new leather, new woodtrim and wooden gearshift, received a thorough cleaning and I added the new Mercedes/BMW tires that make the car look sporty; like the wide tires on the new E's and S's ...to better give you a mental image, the wide tires like are mostly on the BMW M3. Now it has AMG sports rims and the car just looks brand new.
LASTLY, I received my new water pump and starter today from Mercedes-Benz and an expert whom I know personally (subtract labor here) will install them for me on tomorrow, so I'm looking forward to driving it again.
Well, I discovered that another darn problem has arisen. Much like you have described, the car cranks at will. So, knowing nothing about cars I ordered this starter thinking that would resolve it. Well, I'll put the starter in there, however (1)the battery was not fully charged and now that I had it charged, it starts easier. Do that first, even though it may sound stupid.
1) Have your battery completely charged.
2) People will say check your O3 sensors. Well, I've learned that the O2 sensors don't even kick-in until your car has been heated up a while and reaches an extraordinarily high temp, so those things do NOT affect your start-up. That is a myth.
3) Check your fuel rail! This is the tube that runs along the engine from front to back, which each injector is fitted into. This tube is there to make sure ample fuel supply is being transported. A lot of times, having problems starting can be a fuel problem, not necessarily an electrical one.
4) Make sure everything is tight and wipe-off the edges of all connections.
These things sounds stupid and 'elementary' but this board in 3 days, has saved me a TON of cash by simply blowing, or wiping off dusty sparkplugs, etc etc that I'd normally ignore.
A dealer will find something major that will need to be done in the next few yrs, diagnose that as the problem...perform that, charge you out of your butt and then, while he's doing that, will act like he did you a favor and "Oh, while I was in there I saw [insert the real problem here] and went ahead and tightened it up for you. nothing major."
LOL. Check all connections man. The car is a Mercedes, something is loose, or needs blowing off. The fact that it does it occassionally, instead of every time, tells the story. Do a little summer cleaning.
...and then after that, have your car washed and detailed. It'll feel better.