How drain water from heater core?

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.

You could try spinning the pump by hand? Surely it wouldnt take much to just do one circuit around the block?

Though... wouldnt your heaters aux pump circulate water with the ignition and heater on? (Without the engine running?)

To remove water from a heater core I have always disconnected the inlets and outlets. The blow air through these ports. Don't know how successful this would be with a BMW heater core

into one... be prepared for a facefull of coolant though. Blow through all of them going into the firewall until your certain you have most of the water/coolant out. Alternately, remove hoses at firewall, cap off one an fill through one of the others until coolant comes out.. use a 60/40 mix for lower temp protection, There are two circuits for the heater cores so you have to fill both then cap off the piping, shouldn't freeze that way. If you use straight coolant the freezing point is higher as seen at this link, so don't put straight antifreeze in.

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Originally Posted by Gene in NC

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.

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Bill R, thanks for the tips, especially more than 60% EG. Low temp in Raleigh tonight 9 above. Once in maybe 20 years we'll get down to nearly zero.

What I'd really like is a power flushing setup like the Prestone/Peak flushing kit. Used them on my US big threes and 2002s. Splice "t"'s into the heater hoses for:

1) Easy power back flush,

2) Easy fill if the heater hose is high enough, and

3) Fit a metal screw type valve/core in to the cap on the "t" for a full coolant system pressure test, including the radiator cap. Bicycle pump with built in pressure gauge is only addition required. Dirt cheap and should lead to more frequent flush/fills.

See the adapter at any parts store that sells EG antifreeze.