I finally bought the Bentley manual (Amazon, $118, next day shipping,*and $5 MP3 credit).

Arrived today and thrilled at the quality of the book, pics and recommendations. I wanted to quickly check up on the coolant drain/fill on my 07 525 (N52 engine). The book describes the procedures well on 170-7 section. Draining the coolant - radiator drain plug is notified properly. N54 engine block drain plug and v8 engine drain plugs are mentioned. But there is no mention of the N52 engine block drain plug. Couldn't find it. Drained about 6quarts of coolant from radiator and re-filled it. The total capacity is about 10.x quarts, so I guess 4quarts remained. Not sure how to drain it all. Any clues?

thanks
PN, SJ

 

No drain plug on N52 engine.
You must use the car's built-in automated bleed procedure.
See this thread. I've not tried it, but it appears comprehensive.
E90 N52 Engine Coolant Change - BMW 3-Series (E90 E92) Forum - E90Post.com

 

Thanks for confirming this!! The E60 has more space and it was fairly easy to just find the radiator drain plug and loosen it to get about 60% of fluid out. The procedure to remove the tough hoses to get the remaining 40%, I am not sure I would do it. I may just do the bleeding process, and drive around a bit and re-drain another 60% and re-fill to get most of the old coolant out. And do these drain/fill every 2/3yrs - I might be OK. (just escaping the hard-work).
Bentley manual says to drain from the radiator drain-plug, and then re-fill. Then run the air-bleeding procedure (12min), and then re-fill after the air-bleeding. So they seem to agree about not taking out the remaining old coolant.

 

I did the same at 45,000 miless in my 07 530Xi and drained only the radiator, reserve tank and anything I could squeeze out of the radiator hoses. Drained about 7.5 liters or about 65% of capacity (11 liters). Old radiator fluid appeared to have the same blue-green tint as new fluid and was absolutely clear. I will change in another 30,000 miles.

 

yeah i just bought that manual its awesome