adiaw83,

If you just open the petcock on the radiator, all you drain is the radiator. That's what I did. You need to remove the thermostat to get all the old coolant drained out.

Someone suggested removing the block drains. This is what the manual says to do, but I'm mighty leery of removing block drains that have been in the car for probably 20 years.

My best advice is to drain the radiator through the petcock, remove the thermostat and reinstall the housing. Then fill with water, run to mix, and drain through the radiator petcock. You'll have to repeat a few times (4-5) to get most of the old fluid out.

Without the thermostat being removed, you'll leave the engine full of old coolant.

Sholin

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What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.