4.8l N62 coolant flush.
 

Is it common to do a coolant flush just by draining from the plastic cap under the radiator, and not from the drain bolt under the wheel well? I know I won’t get out all the fluid out, but I think it would still be better than not flushing the system at all.

I have an 04 E53 4.4i (N62).

I did my flush just using the radiator. Removing and reinstalling the two bolts on the engine was above my skill level.

Some tips:

1. Definitely get a coolant funnel. I made an adapter for mine with an old radiator cap which sealed better than the adapter in the kit.

2. Best with two people, one to keep the funnel filled with distilled water as the other monitors below and reseals the drain plug. I did five flushes with two gallons of distilled water each cycle, 10 gallons total. You have to get the coolant up to running temperature each time, best with the heating on full blast, from what I remember. Then, the last fill was undiluted coolant.

3. Get a new drain plug, just in case the old one is worn. They are inexpensive. Mine was also an original that didn't have the hook that keeps the plug from dropping to the ground. The hook is useful!

4. At least on the e53 N62, the radiator doesn't hold half the total fluid, so I ended up with about 45% coolant - 55% distilled water. I top off with pure coolant when it needs a little.

5. Get the BMW approved fluid. I got the Zerex equivalent from FCP Euro.

6. You'll notice the brass plug I got for the reservoir... I read mixed opinions. This one has held up great after nearly two years. Mine still has the original reservoir.

7. Use the floating gauge to make sure you don't overfill the reservoir. Overfilling is probably the number one reason they explode.

https://i.imgur.com/m5iXMSO.png