Well I finally tracked down the cause of my dissappearing coolant on my 1989 190e 2.6.
It seems the hose from the upper rear of the engine has a small hole in it near where it connects to the engine. This hose then goes through the firewall.
Does this hose connect to the heater core? If so, would it require removal of the dashboard to replace it?
Any help would be appreciated.
The car car is currently for sale so I would rather not pull the dash to fix it unless I really have to, any ideas?
Sorry I don't have pictures, but looking under the hood it's at the very rear of the engine just several inches below the valve cover coming from the right hand side. Approx 3/4" dia. It has a couple of 90 degree bends before going throught the firewall.

Thank you

Paul

That hose may actually feed into the heater control valve in between the 2 firewalls. It may actually be leaking from that valve or the small plate on top(about 2"x2") may need snugging down.

Sometimes when the monovalve insert is replaced the plate just mentioned is not snugged down enough and coolant will leak giving the impression that one of the hoses in the near vicinity is the culprit.

A cooling system pressure tester will definitely isolate it.

Mike,

Thanks for the reply. The leak is definitely the hose itself very close to the engine.
When you say this hose may feed the heater control valve between the two firewalls, is it easy to access this valve/connection to change the hose?

Thanks again

Paul

Hose is inexpensive and easy to replace. You just have to take off the plastic plenum screen - remove some of the rubber hood seals (They just slip off - not glued.), a handful of screws and some tabs - slip it out from under the wiper seal. Pretty easy to figure out.

If the heater control valve leaks it will usually drip out the plenum drain and onto the top of the transmission. You should check it carefully as a leaking heater control valve is common.

Duke