Hi I just bought one too and I'm very happy!!!!! What a nice car heheheh!!! 1999 C240 V6 Gasoline 97.000KM. Mine I bought from a uncle that lives in another city/state than I drove it for 1.000Km..., really testing the car and it was perfect for two weeks.... and than my head eaches began...... the car simply failed on me after I started it up, drove it for 5 minutes, parked it and than when I went to start it up again, it did... but... I had loss of power and the car started to misbehave not working as it was 5 minutes before... and I had done nothing to the car..... remeber I just bought the car... I hadn't enjoy it yet heheheheh.....

Problems: Reasons and solutions

Fuel tank was dirty = First emty the tank, clean the filter that is inside the tank (27mm socket) / Changed the fuel filter and old hoses / Cleaned the fuel pump and tested it

One fuel injector wasn't closing and was flooding a cylinder = Cleaned and tested the line until the fuel injectors with air / Cleanead and tested the injectors / Changed the little filters that goes inside the injectors / Changed all o-rings / Just cleaned correctly the bad injector and it got back to work so I keept it, all injectors were having the same pressure and volume.

And than I went to start the car and it wouldn't start.... Here I am again.... a poor dude that decided to buy a Mercedes....

W202 Mercedes TBI configuration = When you remove the battery your TBI loses it's setup and then your car starts up with a very weird behavior, totally different than it was before.... (battery remember?) the butterfly doesn't open, not allowing the air flow to pass..... so your car doesn't work with the correct rpm's and gets crazy, weird noises, not nice....

Solution: Enter in the car, close all windows, turn the key until the lights on the dashboard gets on, wait for 6 seconds until the car finish the usual auto test that it does every time you turn it's key, press the speedometer all the way down, count mentally until ten and than turn the car's key off BUT DON'T release the speedometer pedal, leave your foot there for 5 more seconds, remove your foot, now wait for 3 minutes... after that try to start the car, it shall work, if it doesn't do this procedure again because it does work, it saved me from spending money with the mechanic every time I have to remove my car's battery.... If you don't believe search for: transmission reset mercedes w202, it is the same procedure.
After I tried 3 or 4 times it worked thank god!

So I went to start my car up again and it worked!!! Man how happy I got! So far I had spent USD50 plus my time. Than I went on a ride of 35km to test the car and on the middle of the ride I realized the car started to lose power and it's lights were getting weaker and weaker and the car also weaker and weaker, oh my god oh no.... again nooooo..... and at a certain moment I decided to stop the car and tow it to my house.....

Problem: The battery wasn't being recharged by the alternator and this car consumes a lot of electricity to make everything work properly.....

Solution: Test if the alternator is working, use a multimeter, connect it to the battery and start the car up, it shall read 13.5V and above to be good.... if the alternator isn't working your battery voltage will only decrease with your car working.... Mine the alternator was bad BUT IT WASN'T.... I went underneath the car to check if the alternator cables were ok and than when I put my hands on the terminals (the battery MUST be disconnected my friends) the bolts on the terminals were both loose... so for my luck my cost was zero, just my time and patience again heheheh....

After that I replaced the radiator solution, differential oil and now I'm enjoying the car!!! What a nice car! Mine is a 1999 W202 C240 made in Germany.
I totally recomend this car and I hope I have helped other people that have old Mercedes.
Adriano