Shade tree mechanic method;jack the rear of car as high as possible and
let gravity do the work.

Shot in the dark;vapor lock in heater core?!?!

thanks, I _was_ hoping it might be something else, but thought so.  Let me
guess .... the plug is nigh on impossible to get at or to get out.  Seems
I remember something around the exhaust manifold on the block that might
be the drain plug.... correct?

cheers, guenter

ps.  why the h... would MB engineer a system whereby the rad drain screw
only drains half the system..... arrgghh

Thanks, for the tip - good idea and will probably save a whole bunch of
likely aggrevation ..... my citric acid flush in conjuction with half-
concentration antifreeze should have cleaned the engine nicely by now.

By the way, I do believe the drain 'plug' is actually a nipple-nut combination
that is located right beside the cat converter and just behind (looking from
front) the engine mounts.  What puzzles me is why this drain (I'm pretty
sure it must be) is located apparently pretty high up on the engine.... I
would have thought it would be lower down.  But I guess the water chanels in
the block are only in the top part of block where the cylinders are.

cheers, guenter