Coolant leak?
 

I noticed this morning that there is a considerable amount of what appears to be coolant (it is greasy but running down hill in the garage so I can't tell the color) on the floor of the garage. It appears to be coming from the pass. side under the space between the engine and cabin. The monovalve was replaced about two years ago and there does not appear to be any leaks there. My fear is that it is the auxillary water pump or worse - the heater core. Any suggestions as to how to test for this other than removing all of the relays and other things and visually inspecting (yes, I am lazy)?
I am fairly sure this is coolant as this happened several days ago as well and the greasy substance dried on the floor but left somewhat of a ghost on the concrete. Also, it appears to do this if the temp. wheel is anywhere above min. on the wheel.

Year and model of the car will help...

sorry, forgot to put that in there - 1990 420SEL.

There is a coolant overflow recovery tank in the fender behind the left front wheel. Peel back the fender lining to expose it. There's a good chance that the hose that leads from the pressurized reservoir to the overflow tank is... uhh... hosed :)

Sixto
95 S420
87 300SDL

Hadn't even thought about that!! Thank you. I will check as soon as I get home - if it isn't raining. Will let you know.

There is a small rectangular shaped plate over the monovalve. 4 screws secure it. Be sure they are all snug. If not, you'll lose coolant.

sixto

Ever clean one of these tanks. I am replacing that hose and the tank is really disgusting.

Haasman