I stopped to try and help a fellow MB'er this morning and was perplexed at his situation. His '90 300SEL was dumping all of it's coolant. The leak was still running and seemed to be coming from behind the water pump, pretty much where the dipstick runs alongside the block, but it was too congested to see where exactly. He said his radiator was just replaced. This was no drip, it was really running out from just that one location. He was going to have it towed and serviced, but I am wondering what was going on. Any ideas? Is there a weep hole on the lower back side of the water pump? I didn't see one on the top where mine is. Hmmmm...