Originally posted by sixto
AFAIK the reservoir overflow hose just goes into that hole with nothing at the other end. That's how it is in the 300SD and 300SE. I've never looked at the 300SDL hose because the air cleaner kinda hides the hose. I can't imagine it's different in a 560SEL.
There was a crack at the bottom of the tank of the 300SD. A quick RTV patch seems to be holding. FWIW, the SD runs at a lower system pressure than the other cars if the cap rating is any indication.
In the 560SEL there is in fact 2 expansion tanks. There is one above the left passenger tire w/rad cap on it, and another overflow reservoir in the wheel well. It can only be seen if the inner liner is removed with about 10 bolts. I ended up ordering a new expansion tank from fastlane, just because it's so damn hot here in Arizona.!!!