How drain water from ('89 525 w 172k) heater core? Car now needs headgasket, but exposure to freezing while waiting for work at repair shop may take out the heater core. Now stored in my heated garage. Heck, water in block too. Couldn't get to block drain plug.

Overheat symptom appeared as pinhole leak from gasket on cover on side of throttle housing assy. Was that the real problem or the weak link from yet another blocked radiator? Have had two blocked radiator over heats on this car previously. Replaced radiator both times and continued on w/o problem.

Wanted to flush cooling system, so I replaced the bad gasket and flushed the system a couple of times. Trouble bleeding led to compression test. All good. But, dip stick and valve cover cap show lots of scum. Now hesitant to run engine to distribute antifreeze to block and heater core, because of water in oil.

Net, how can I get antifreeze into block and or heater core, or get the water out. Coolant, see realoem, does not drain from heater core. All hoses are attached at top of core.