Larry, I know that I have an M104 engine, but when I had a coolant leak that I couldn't detect, I took it to my mechanic and we put it on the lift. He took off the plastic pan, and the weep hole was in perfect view. It was coated with the residue of coolant, so I bit the bullet and had him replace it.
I have replaced the water pumps myself in virtually all of the cars I have owned (except the Ford Explorer), so I had become pretty good at it...
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".