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      10-11-2020, 11:32 AM   #1
ggggbmw
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best way to drain coolant?

So, where are people draining coolant on their cars? And how much were you able to get out?

I replaced the coolant overflow hose yesterday as a safety measure, since it is prone to failure. Also thinking it was about time for a coolant drain/replace, since I'm not sure it's ever been done on my car.

Surprisingly, I did not find a lot of good information on coolant change on the F22. So many good youtube videos and forum posts on other topics, but not this. Mainly, used this reference, which was linked from a post in this forum:
https://f30.bimmerpost.com/forums/sh....php?t=1210850

Based on this reference, I pulled the inlet hose off the water pump. Kind of a pain though, as you have take off 25 screws to drop two different panels to get access. And like any time you pull a hose, it gets messy. Very hard to control the flow, and it tends to splash everywhere. Especially since the pump is above the steering rack and sub-frame.

I got about 4.2 liters out. I haven't found a good reference on the coolant capacity of the F22 with N55 and auxiliary coolant radiator. The F30 reference above indicates between 6.7 and 7.2 liters (w AT), but I don't know if that includes the aux radiator. In any case, 4.1 L is not even 60% of the coolant. With the long life of coolant, half replacement is better than none, but still, it would be nice to replace more.

I also found another reference in a video on replacing the aux radiator, again on an F30:


Has anyone tried draining coolant from the aux radiator? If so, how much coolant did you get out? Access seems a bit easier. And potentially it might be a lower point in the system. I didn't do this method because I wasn't sure on the hose routing, and if it would drain any more fluid, and the 'official' TIS method said water pump hoses. But after getting eyes on it, the lower aux radiator hose does appear to be the lowest point in the system. And access would be far easier then dropping undertrays, and maybe less messy.
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      10-22-2020, 09:16 PM   #2
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I just drained from lower hose off the water pump. I didn’t measure how much came out but it took a full gallon (so really 2 gallons since 1 gallon concentrate and 1 gallon distilled water). I do this once a year or two eventually it just dilutes old stuff in the block and what not. You’ll never get it all out with a vacuum tool
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      10-25-2020, 04:52 PM   #3
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Decided to post this picture of where I drained from. This is looking from the front passenger wheel, up toward the drivers side wheel. You can see clean ribbed edges of the water pump fitting where I have pulled the hose off and the hose is just touching it. You can also see the green form-a-funnel I used to help direct flow. It did keep the coolant off the steering rack, mostly, but the coolant still splattered over the front cross-member and other bits to the front of the car.

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This was actually the first time I've had the under-panels off on the car. I was really surprised to see how thick the power feeds for the power steering rack are. (The red and black cables just in front of the green form-a-funnel.) This shows just how much power the rack motor needs to add 'power' to the steering, and why doing this hydraulically was such a power drain.
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      10-26-2020, 06:12 PM   #4
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Those are some massive cables!! That erack must draw a ton of power. Now I see why BMW went the erack route as the power steering pump must have taken a lot of engine power. I would've it liked if BMW had installed an electric power steering pump with a hydraulic rack.That would have kept the "feel"!
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      10-29-2020, 07:26 PM   #5
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The posts above are correct. You can pull a hose off the water pump and get quite a bit of coolant. I actually did this twice. I did it again a couple weeks later. I just happen to have enough coolant in the shop to do it two times.
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      11-06-2020, 05:00 PM   #6
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Best I can tell, TIS for the N20 says to take off both pump hose and radiator hose to drain (with cap off the reservoir 'ball'). For the N55 in a 235 it says to remove both hoses from the pump. The refill procedure uses vacuume valve on expansion tank (bring pressure to -0.7 to -0.95 bar and then open valve to suck the coolant in). The video shows over 14L in the fill tank it is pulling from, but then looks like they only end up adding a couple (not sure if it is vid of full fill, or just to demo the valve).

Here's the volume listing:
17 00 Coolant, Cooling System Test F87 / N55
Model series F87
Model designation M2
Coolant quantity on vehicles with manual gearbox 10,5 l
Coolant quantity for vehicles with DKG 10,5 l
Top-up quantity of coolant in the event of repair with disconnected coolant hoses. Observe the mixture ratio and filling level! 2,0 l
Test pressure for cooling system excess pressure (in bar) 1,5
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      11-06-2020, 05:06 PM   #7
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Also found this bleeding procedure, I think for after you vacuume fill it. Hope this helps.

-Perform filling operation slowly.
-Adjust coolant level to maximum.
-Close coolant expansion tank.
Installation note: Close the sealing cap (1) until the arrows line up.

Important!
The following bleeding procedure is necessary e.g. when a part is replaced in the cooling system or when the cooling system is refilled.

-Connect battery charger.
-Switch the ignition on.
-Switch on low-beam headlight.
-Set heater to maximum temperature and turn blower down to lowest speed.
-Driving experience switch must not be set to ECO PRO!
-Press accelerator pedal for 10 seconds to floor. Engine must not be started.
-The bleeding procedure was started by pressing the accelerator pedal and takes approx. 12 mins. (the electrical coolant pump was activated and switches off automatically after approx. 12 mins.).
-Then adjust fluid level in the coolant expansion tank to maximum.
-Check cooling system on watertightness.
-If venting has to be carried out again (e.g. if cooling system is leaking), allow DME to fall completely (leave ignition key removed for approx. 3 mins.), then repeat from Point 2.
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      11-06-2020, 07:00 PM   #8
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Maynard thanks for posting the pump activation fill routine. It's referenced in threads I linked to above, but it's good have in this thread too. I forgot to add it to my original post.
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      11-27-2020, 11:55 AM   #9
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I decided to try this and joined the forum to let you guys know.

I got exactly 4L out of it by draining from the aux rad.

Seems like the way to go for a drain and fill. Less stuff to remove and much easier to do without making a mess getting coolant all over everything under there.
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      07-16-2023, 01:03 PM   #10
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Quote:
Originally Posted by Maynard View Post
Also found this bleeding procedure, I think for after you vacuume fill it. Hope this helps.

-Perform filling operation slowly.
-Adjust coolant level to maximum.
-Close coolant expansion tank.
Installation note: Close the sealing cap (1) until the arrows line up.

Important!
The following bleeding procedure is necessary e.g. when a part is replaced in the cooling system or when the cooling system is refilled.

-Connect battery charger.
-Switch the ignition on.
-Switch on low-beam headlight.
-Set heater to maximum temperature and turn blower down to lowest speed.
-Driving experience switch must not be set to ECO PRO!
-Press accelerator pedal for 10 seconds to floor. Engine must not be started.
-The bleeding procedure was started by pressing the accelerator pedal and takes approx. 12 mins. (the electrical coolant pump was activated and switches off automatically after approx. 12 mins.).
-Then adjust fluid level in the coolant expansion tank to maximum.
-Check cooling system on watertightness.
-If venting has to be carried out again (e.g. if cooling system is leaking), allow DME to fall completely (leave ignition key removed for approx. 3 mins.), then repeat from Point 2.
I’m wondering where the bleed screw comes into the process. It seems opening to evacuate air (at least intermittently) during the pump circulation bleed process would make sense. Any thoughts or experiences with this?
Thanks
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      07-20-2023, 09:35 PM   #11
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Quote:
Originally Posted by MarcoZandrini View Post
Those are some massive cables!! That erack must draw a ton of power. Now I see why BMW went the erack route as the power steering pump must have taken a lot of engine power. I would've it liked if BMW had installed an electric power steering pump with a hydraulic rack.That would have kept the "feel"!
Default is 105 amps. You can change it with coding. I dropped mine to 85 amps. Makes the steering heavier, but does not help the road feel.
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