I have a 86's 190E 16V and the radiator ove tank had a pin hole leak
so I went out and got a new one. first question, the part # is different from my old tank but the dealer said is a new part for the car. true? Anyway, got home put the new tank in ......seems simple
but nooooo that damn O-ring was so hard to put in and out!!! I
try and try and fail...finally I bent it a just a little to fit in (still hard to do and almost took out my fingers) so, now everything is perfect so I start the car up......and coolent start to leak out of the hole (where the o-ring and the sensor is).....what did I do wrong...please help, should I not bent the o-ring? (if so it is so damn hard to put back tho) does the new tank have to use an new sensor? and some coolent drip into the plug (the plug that plug into the sensor) will this cause the coolent light to stay on in the dash? (because before it was okay!!) ..........please help thanx

P.S I promise never to touch my benz again ....everytime I do anything to it ...something else goes wrong......

John