Coolant flush question

[BamaBMWgirl]

I'm getting ready to do my own coolant flush(including engine block). After watching several videos and reading numerous "How to's" I'm a bit confused. Emptying and refilling is not exactly a flush. That's just a change.

One article advised emptying the system and then refilling with distilled water, bringing the car up to operating temp, then repeating the process but filling the final time with coolant. Since I found green sh*# in my expansion tank, this sounds like a good idea. I want that crap out of my car!

Any thoughts, words of wisdom, suggestions?

[MarcoZandrini]

Definitely perform a true flush by fully draining the cooling system, including the block via the block drain. You'll likely get drenched with coolant when you remove the block drain! Fill with distilled water and properly bleed the cooling system. Get the engine up to full temperature and allow it cool a bit. Drain and fill with a 50/50 mix of BMW coolant and distilled water. If you're really anxious you could add a gallon of vinegar to the distilled water fill. But, I recommend doing a distilled water flush after that flush.

[BamaBMWgirl]

The vinegar sounds like a great idea! Thanks for that tip. So, I'll need approximately 9 gallons of distilled water. 3 gallons DW + 1 gallon vinegar for the initial flush. 4 gallons for the second flush, and 2 gallons to mix with the 2 gallons of BMW coolant. Does that sound right?

Also, I need to do the bleed with the key engaged, heater temp at 91 and fan on low, right? No need to press the accelerator for ten seconds and then leave it engaged for 12 minutes? That's for a different model, correct?

[BamaBMWgirl]

Dumber question...what do I do with all of this used coolant and flush water? Can I drop it at the auto parts store?

[dhurley34]

Jiffy lube will take it.

[legoman67]

The vinegar sounds like a great idea! Thanks for that tip. So, I'll need approximately 9 gallons of distilled water. 3 gallons DW + 1 gallon vinegar for the initial flush. 4 gallons for the second flush, and 2 gallons to mix with the 2 gallons of BMW coolant. Does that sound right?

Also, I need to do the bleed with the key engaged, heater temp at 91 and fan on low, right? No need to press the accelerator for ten seconds and then leave it engaged for 12 minutes? That's for a different model, correct?

Thats for the e9x chassis. The e46 are more old school.

With the car on level ground or the front slightly raised, remove bleed screw and fill the expansion tank until you have coolant coming out the bleed screw hole(it will be slow as you get near). After that close everything up and go for a drive with the heat on full blast. Drive for long enough to get the car up to temp (10 min is usually enough). After that let the car cool down for a few hours and then recheck and adjust your coolant level based on the stick in the expansion tank, Typically it will be very close to perfect, but the odd time you may have to add a little.

If your only concern is some green coolant in the system full flushing is unnecessary. Just fully drain the system from the rad and block drains, then fill with fresh blue mix. The green left will be so diluted it wont be detectable. Most green coolant you will find on the shelf today is aluminum safe anyways.