Hi all. I’m taking over a 2011 BMW from my in-laws and decided to do some work on it myself.
I’m going to flush the cooling system. I know I need to capture and recycle the old antifreeze, but after I flush the system with water do I need to recycle that water too? Or can I just put that down the drain?
The antifreeze/coolant that you drain needs to go to a hazardous waste facility.
Do NOT put it into a sewer drain or drain it into the street, where it will attact and poison animals!
This site pertains to my state, but–hopefully–your state has similar hazardous waste disposal sites:
I believe the OP is inquiring about the rinse water he will use in the system after he’s properly disposed of the coolant.
The municipality I’m located in allows disposal of used antifreeze down the drain.
Of course, you can’t do this if you have a septic system.
Check your local ordinance.
Tester
In this area we take used anti-freeze to a special drop off location. At some point the flushing liquid will be so diluted it can probably be poured down the drain, but not sure what the max concentration would be. Best bet is to just take it all to the drop off location and let the experts there decide.
Be careful w/pets around antifreeze btw, don’t let pets or any other animals near it, some are attracted to the sweet odor, and consuming it is very dangerous to their health
First, DON’T FLUSH THE COOLING SYSTEM. Check you coolant for clarity. If it is clear, colored but clear like a tinted plastic or glass, it is still good. If it is cloudy, then it is still good but in need of a drain and fill ASAP. If it has turned to a muddy brown, well then you need a flush but that should be done by a professional, not DIY.
Just drain and refill. Refill with a coolant that meets the manufacturers specs or just buy the coolant from a dealer. Yes it costs more from a dealer but compare the additional cost that only occurs once every five years to the cost of filling the gas tank every week, that’s perspective and it gives peace of mind.
You can either get the premix, which for most people is what I would recommend or you can get the concentrate and premix your own. The latter is a little cheaper but you need an additional empty gallon container or two and unopened gallon jugs of distilled water and a funnel to carefully measure and mix to make your own premix.
A lot of amateurs will recommend pouring the concentrate into the system and then adding the distilled water, but I can pretty much guarantee you wont get it right, but if you are off a little, it really doesn’t matter in the long run.
You will leave a little of the old coolant in the system this way, but as long as it didn’t reach the muddy stage, no harm done. If it was cloudy, then plan you next coolant change for three years instead of five. If you only drain the radiator and not the block, and the existing coolant is clear, then plan you next change for three years instead of five, two if it was cloudy.
By not flushing, you will avoid getting contaminates in to the cooling system. Flushing, unless done on professional equipment will get contaminates into the cooling system and shorten it’s life.
Ours also, that would be a sanitary sewer drain, not storm drain. Toilet is probably the easiest. As tester said not good for septic systems.
I can easily do a radiator flush, but I won’t. I prefer taking this someplace that has a recycle machine that will dispose of the fluid properly.
What about those coolant test strips that test if the coolant is doing its job of preventing electrolysis? Very important for Fords with internal water pumps. Apparently they corrode around the seal if the coolant fails and it’s $2000 to fix. More if it isn’t caught soon as it contaminates the oil.
@TheWonderful90s The test strips I am familiar with test the pH of the coolant. By the time those strips test in the danger zone, the coolant is very cloudy. There is also a way to test acidity using a voltmeter, but the result is the same, any system that exceeds the voltage allowed is very cloudy. I would change at the first hint of cloudiness.
Edit: I would encourage you, or anyone else concerned about their coolant, to test it for pH or any other go/no-go test and if the coolant is clear and fails, I would surely like to know. On the other had, if it tests good but is cloudy, I would strongly encourage you to change it anyway. Coolant can be a little cloudy and still provide some protection, BUT not for long. It can go from go to no-go very quickly.
Second edit: @fwang01_186334, make sure you know how to bleed the cooling system before you start this project. You may need some special equipment to properly bleed it. If not properly bled, it will overheat and could lead to a blown head gasket. Google for a BMW specific forum and ask there. You will likely hear form people who work on and/or own BMWs
I am huge on the brake and coolant test strips, but be careful…
I always checked history on a customers vehicle to see prior recommendations as well as the maintenance history… I have worked with great mechanics that I would trust anything they said that a vehicle needed but I always did random shop checks just to keep them on there toes as well as always double checked the mechanics that seemed to rubber stamp the WO’s…
Anyway, we got a new batch of coolant test strips and I noticed a lot of guys that didn’t normally recommend coolant flushes had recommended them even on vehicles that I wouldn’t think would need them and it threw up a red flag to me, not hard to do lol, so I did recommend a few mileage only based flushes and informed the customer that I didn’t see any issues and that the coolant looked good so they may have had it done elsewhere, then I got one from a very trusted mechanic that brought me the test strip (as most did) and said it failed but the coolant looked great, I checked history and the same mechanic had just flushed it last service… So I checked our new coolant in the 150 gallonish tank and it failed, so I said don’t use that coolant and so I ordered a few different gallons and makes of coolant from a few different parts houses and tested them and they failed… So I went over to a guys box that hardly every used them cause I new he had some old ones and ALL the new coolant we had checked out great even the few vehicles that were still there that had thrown a red flag up…
Bottom line is, always check your new strips against known new coolant, as I had to throw away thousands of new test strips as well as inform corp to send out an email for the other shops… But that was the only time that happened…