How to replace coolant?

[RussellP]

As per topic title, does anyone have any step by step instructions to replace the coolant?

Thanks in advance...

 

[bcworkz]

There's this, it's in Russian but Google translate works fairly well: http://tis.bmwcats.com/doc1080540/

What they don't tell you though is you do not get all the coolant out by draining it. Refill with plain water, run the engine, drain again, repeat until the water is fairly clear. Determine the total coolant volume from some published specification to calculate how much concentrated coolant you need to add for the correct mix, usually 50:50. Do not use pre-mixed coolant as you will never get the correct concentration.

Drain one last time, then refill with the measured amount of concentrate. You'll probably find just the concentrate will pretty much replace what was drained, it will mix with the plain water that did not drain when the engine is run. Top up with water as needed, then perform the bleed procedure.

If you were not able to even put in the needed amount of concentrate, drain off some of the weak mix to make room for more concentrate. There's some calculation of how much weak solution to remove in order to add concentrate back in to achieve the required ratio, but it's been too long since I've been in school to be able to suggest what that might be.

 

[ben g]

It's an easy enough job, just take the coolant hose off from the bottom of the expansion tank. Had to do this when my tank cracked.

Make sure you bleed it properly though, using the bleed screw on the pipe (i think) to the left of the expansion tnk.

 

[RussellP]

Thanks for that, so does that drain the radiator and engine block?

 

[bcworkz]

Drains the radiator, expansion tank, some of the hoses and a small part of the block. Seems to be only about half of the total capacity. Not sure what's involved to fully drain the system, it's likely quite a chore.