This concerns my 1980 300sd. Yesterday I noticed lots of coolant on my garage floor as I was pulling out. I could not locate the leak while the car was running and it appears that the leak only occurs when the car has been shut off for about an hour. Tonight I found that the leak is coming from the bottom of the water pump housing. The pump itself seems to be completely dry. I have changed water pumps on these diesels before but never have messed with the housing. Anyone change one of these out before? Any suggestions on tackling this job?