To tell you how the whole story ended, I had received at the end of may 2008 the water pump by mail with a replacement idler pulley. As I didn't have time to perform the job, I wanted a couple of weeks, using the car for 50 miles runs to go to work and checking each time coolant level. About 3 weeks later, one of my good friend got in a motorcycle accident with his wife and they both were lightly injured but needed to talk and be cared for. As they live over 100 miles from my home, I drove to their place one sunday and came back later in the evening. The morning after, my wife was supposed to take the car for some shopping near by. As she started the car, she noted an alarm about coolant level and she warned me immediately. I told here to stop the car right away. There was plenty of coolant on the ground and level was les than 40%. So this monday morning, I went into this job after having bought an inverse torx sockets set. The job went well and my only problem had been a torx bolt hidden beind the upper cover where there are a couple electric switches; as I did not remove that cover enough, I did not see the torx bolt beneath it. So I was trying to remove the water pump and that didn't work that way. I finally discovered the torx both beneath and removed the waterpump very easily. I cleaned all gasket residus and put the new rubber one in place before bolting back the new water pump. After that, putting all new coolant in and checking it everyday during a couple weeks to add a little as needed. That was quite a faisable job and I would do it again if needed. I costed me near $300 Can including a new belt ($60),idler pulley ($40) ,water pump ($150), MB coolant ($46) and distilled water ($4); compared to a least $700 at the dealer, that worths doing the job. I want again to thank Zewerr for everthing he told me about this job.