You can get the thumb pump at fastlane, its a great price, and it will never leak.. (Fastlane is at the top of this page, there is a banner that says "New and much improved FASTLANE" ) It is under "diesel injection" Then "primer pump" (after you enter your car.)You will not need the whole Primer poum assembly, just the pump itself. (I just did this on my 300SD) You will probably need a crows foot wrench, and I fairly sure it is a 17mm.