Chris,

I just noticed that you removed the thermostat. Why?
The thermostat has nothing to do with the coolant loss problem. MB Diesel engines are designed to be run with a thermostat and it should not be removed.

Sorry, there is no quick low cost fix for a leaking head gasket. It must be replaced and the head checked for warp and cracks when it is off.

Don't give up now. This shouldn't be that expensive of a repair after all you have already done to the car and it will give many years of service.

P E H