I just overhauled my entire cooling system on my 2001 530i. It went pretty well...no leaks thus far. For this car, I noted some differences from cn90's most excellent write-up:
Regarding the reservoir and its small hose that attaches to the opposite side of the radiator: I found attaching this hose to the reservoir first was significantly easier than any other method. I didn't have the room to attach the hose to the reservoir (with it attached to the radiator first) because the length of the hose was too short and the shroud was in the way. I used a stick to keep the shroud raised up to allow me to attach the other end of the hose to the radiator second...MUCH EASIER.
Also, pick up two "BMW" hose clamps for the reservoir hose. The ones we typically get at the auto/hardware store just can't take what I feel is the required torque to cinch these hoses down good. I went to my dealer and it took him some time to locate the screw type that was roughly the same size as the original crimp style that came from the factory. Here is the part number: 07 12 9 952 104 from the fuel filter diagram (http://www.realoem.com/bmw/showparts...18&hg=13&fg=10). Yeah, they were a tad pricey at the dealer at around $3 each but worth it for no leaks, right?!
I did not bother filling the system with new fluid until everything was done and completed...it was just easier. I was able to put 11.1 quarts of fluid in relatively easily. I filled the system VERY SLOWLY through the bleeder screw hole on the upper radiator hose...agonizingly slowly. I was hoping if I did this that I wouldn't trap air. I left the reservoir cap and its bleeder screw there open the whole time and air was bubbling out as I slowly filled. After that, it was a matter of running the engine, heater on high set to 90F, and then keep checking the fluid level off and on and after a cycle or two of this over a couple hours, I had all 11.1 quarts into the system. I suggest you keep careful track of the amount so that you are sure.
Finally, attached is a pic of a cheap plumber's tool that will aid you in knocking the fan bolt loose in 10 s...along with a 1 1/4" wrench if you don't have a 32 mm one.
2001 530i/5 (E39), Topaz Blue/Stone Green/Black (97k miles)
2005 545i/SMG (E60), ED Order, Titanium Grey/Grey (lease transferred...no longer have)
Last edited by Ågent99; 09-06-2010 at 01:49 PM.