thermostat body cover

did anybody replaced the thermostat body cover with the engine inside?
the drainplug ( 10300240 ) is broken and I can not remove the rest from the hole without taking this cover out. it is soooo hard to reach there and the front 2 nuts for removing the cover are not reachable when the complete thermostat housing is inside.

any good idea???

 

already nearly done

not such a big deal as I thaught at the beginnig

had to drain the coolant out of the 2 radiators to safe the fluid. then I loosen the upper 4 short hoses ( 2 directly at the thermostat housing and the other 2 from the pipes left and right going to the radiators ), unscrew the upper termostat housing from the lower one ( only 2 screws M 6 ) and took the upper housing out. rest of the bleeding screw is drilled out. a larger thread ( M10 x 1,5 ) is in the housing. I will make a 2 piece bleeding screw ( a screw with thread M10 x 1,5, inside a small hole with about 2,5 mm, then the half of the screw inside thread M6 x 1,25 and inside this thread then a normal bleeding screw form a brake caliper ) and hope all will work fine later