Tips/tricks for coolant flush?

[Cubieman]

This will be my first time performing a coolant flush on the M3. Just wondered if anyone that has done this a few times has any advice that might make thing easier. As I understand it, there is no traditional drain plug like on many other vehicles so the job can get messy.

I purchased one of the coolant refill/air purge kits as well as the ECS aluminum bleeder screw and a coolant drain plug crush ring. Going to get a new 5 gallon bucket today for the 50/50 mix. Not sure as of yet how exactly the fill/purge tool works, but thats what the instructions are for. From what I understand you dump all of your 50/50 into a bucket and let the tool suck it up and introduce it into the system.

Also, I have about 2.5 gallons of OE coolant, one DIY said he only used one gallon coolant/one gallon distilled water, didn't seem like that would be enough, but, I don't know capacity because I have never done it.

I realize there are DIYs and Google and my Bently manual but there always seems to be little helpful bits of info I can get from you guys and I sure appreciate it!

[2004LSB]

From my experience flushing the cooling system in the past, it is a VERY messy job. I too bought the ECS coolant purge / fill kit hoping that it would make the job clean and spotless. Are you referring to this specific tool?

https://www.ecstuning.com/b-schwaben...SABEgInXvD_BwE

If so, I had no luck with it trying to extract the old coolant out. Hooked it up to a decent sized compressor and it wouldn't extract anything.

As you may know there are two spots you have to drain the coolant from: 1.) There's a tiny bolt on the side of the block and 2.) Unplug the temp sensor on the lower radiator hose. I find if you start with #2 first while keeping the cap on the expansion tank sealed, it sorta controls the flow a little bit better. Be ready with at least 3 - 4 Home Depot buckets, or a thin and very wide profile plastic container underneath the car to start catching the coolant. #1 gets REALLY messy!

Also, be sure to replace the O-ring on the temp sensor. From what I remember, 1 jug of the OE coolant and 1 gallon of distilled water should be sufficient. If you want, pickup an extra gallon of distilled water to top off in case you need a little extra.

[Ahmed.Alghoul]

I was planning to do radiator flush for the e46 m3 as well,I was reading the procedure on newts.info
then I stop on the last step where they are asking to don't remove the bleeding secrow.
are this information correct????

[Tbonem3]

Our system self bleeds (like the clutch) with the e-tank at the highest point. You don't need to mess with that little bleeder screw on the upper hose elbow to the rad. Squeezing the upper hose seems to help move things along. Also, drive the car and get it hot, when you're done. Once cold, like the next morning, you'll usually find you have to add some more water in the e-tank.

I don't think only 2 gallons is enough. I do one gallon blue, 2 gallons distilled agua, but you don't use all 2 gal of the water. Total capacity is 10 liters or 2.6 gal.

[r4dr]

If you buy a handful of 1 gallon jugs of distilled water from the grocery store, you can pour half out of the first one and mix 50/50 in there. Easier than filling from a 5 gallon bucket and you don't have to worry about dirt in the bucket getting into the system.

[Ahmed.Alghoul]

Thank you I used to remove that screw every time I bleed the system. That what I saw on youtube DIY and what is make that Strange no one of the m3 owners noticed that !!!

[Tbonem3]

Ya it was like an e36 holdover or something. I do miss the bottom drain on the e36 radiator though.

[Cubieman]

I don't think only 2 gallons is enough. I do one gallon blue, 2 gallons distilled agua, but you don't use all 2 gal of the water. Total capacity is 10 liters or 2.6 gal.

So you are just topping of with distilled water after the initial 50/50 (1 gal. Coolant/1 gal. H2O) is in the system? Why not mix more 50/50, not necessarily essential when just topping off?

[heinzboehmer]

So you are just topping of with distilled water after the initial 50/50 (1 gal. Coolant/1 gal. H2O) is in the system? Why not mix more 50/50, not necessarily essential when just topping off?

From TIS:

If the proportion of antifreeze is less than 40 % to -29 °C (i.e. the water content is higher than 60 %), not only the degree of protection against freezing, but also corrosion protection is reduced. When the water content is too high, this can lead to premature excess temperature in very hot weather or hot climates and as a consequence lead to coolant being ejected out of the system and damage to the engine through excess temperature.

This means that it is essential that an antifreeze and corrosion inhibitor is added even in the tropics.

Too high a concentration, more than 55 % down to -47°C, leads to deterioration of the cooling properties (heat transfer) and protection against freezing-up is modified in the opposite direction, i.e. it also deteriorates.

Basically, the concentrated coolant that BMW sells is designed to work at a certain concentration (50/50) and other concentrations will start to change the physical properties of the mixture.

Since antifreeze is designed to extend the temperature range at which the liquid in the system stays liquid (and thus continues to be able to transfer heat efficiently), getting the mixture correct is most important in places that get closer to these extremes. In a mild climate like that of SoCal, reaching a perfect 50/50 mixture is not terribly important, as the outside temp will probably never be low or high enough to greatly affect the heat transfer properties of just water. In Nebraska, however, I would try to stay as close to that 50/50 mix as possible, with the main worry being that too much water might cause the mixture to freeze and potentially crack cooling system components.

The other thing antifreeze does is protect against corrosion inside the system. However, if you use distilled water there shouldn't be too much risk of corrosion to begin with.

To answer your original question, since the amount of liquid you are adding when topping off is small compared to the amount of liquid already in the system, the mix won't be affected too much. However, I would personally still premix more 50/50 and top off with that.

[Tbonem3]

So you are just topping of with distilled water after the initial 50/50 (1 gal. Coolant/1 gal. H2O) is in the system? Why not mix more 50/50, not necessarily essential when just topping off?

I actually do like a 30/70 mix or so, not scientific, but more water than coolant. It never gets that cold here and I don't drive the car in cold/rain anyway.

[Cubieman]

Gotcha, makes sense.

[Obioban]

I, too, would stick with a 50:50 ratio (and distilled water only). Coolant is also a lubricant and corrosion inhibitor— neither of which I want to be short on.

[Arith2]

There's salt, sulfur, fluoride, chlorine, copper, and whatever chemicals didn't filter out of tap water. They can also make your coolant conductive leading to parasitic loss and electrolysis within the cooling system. the universal spec is the coolant must have less than 300mV in it, according to my school book. Distilled all the way. The TIS says one thing but the BMW bottle says you can vary mixes from like 33:66 to 60:40 in colder climates. I don't have a bottle on hand but you can look on yours to verify what I'm saying is right.

[bigjae46]

I just used a banjo bolt and some AN6 line with a plug on the end to make draining the block a lot easier and less messy.

might be worth adding a manual valve inline as a fail safe for a street car.

Now my car no longer pees on the toilet seat...

[bigjae46]

I wonder if you can get more coolant out if you have the ignition on and the HVAC fan on to turn on the aux pump?

I’d scope out O’Reilly’s. Everyone I’ve been in carries Zerex G05 which is approved for use in BMWs.