Gary ,a few tips that may help,yes just drain from your bottom radiator tap about
2-3 pints,then to remove thermostat housing ,probably have to remove about 3-4 bolts that support
fuel injection lines that cover 2 of the thermostat bolts.Then start by removing the 4 bolts on housing,
but be very careful when loosening these,as they are steel bolts into alloy housing,and they can corrode
inside and can snap or break ,so when removing loosen a little at a time and if the bolt starts to tighten while backing out stop,
squit with pb blaster etc,wait a while,then turn back in a little then out ,etc,etc,until its all way out.
When 4 bolts are out, tap top housing with plastic hammer until free,then clean all surfaces up,fit new thermostat and oring,
Mercedes thermostats have a small ball valve on one side,that should be position at highest point, if your thermostat sits at slight angle.When finished bolting all down,and when you are ready to connect top hose to housing,poor as much coolant down
into the top hose into radiator at an angle until its starts running back out, then connect hose to housing and tighten all down.
Use the same coolant as you have always used, make sure your radiator tank is a little over half full and then go and turn your heater
controls on to hot.You are now ready to start and run your car. Only drive about 1/2 mile close to home,watch your temp gauge,
return to home ,watch your temp gauge,by then your thermostat should have opened,and it will purg its self, when you park back
at home, then check level in tank after it cools about 1 hour, do this couple of times until tank is at correct level.
It is important that the correct operating temp is reached as this also affects the fuel injection operations of the engine
a stuck open thermostat, the engine takes for ever to reach operating temp ,plus is a sign that it could be running cold.regards.
