[dbjb]

UPDATE: To see images, make sure to use Chrome as your browswer AND download the extension "Photobucket Hotlink Fix"

After a few searches, I could not find a DIY so decided to put one together.
You will see that I only performed a partial flush but the steps needed to completely flush the coolant should not be much different. Why would I be okay with only removing some of the coolant? Well, I plan on tracking my car. I wanted to run about a 25/75 coolant/water mix. Therefore, draining most but not all of the coolant was fine by me. Also, to completely flush the coolant, you must remove your FMIC. I chose not to because removing my AM FMIC would add time and as stated earlier, my goal didn’t require 100% flushing. Please note, this is for an e92 335i with Automatic Transmission. I am only supplying some images as many of you already know the basics.
Now, let’s get on with it.

1) Allow vehicle to cool down then raise using jacks or ramps.
2) Remove the undertray (approx 20 8mm screws)
3) Grab your 5 gallon bucket and place under AT heat exchanger.
4) Unclip hose as shown.




5) Slowly pull hose off heat exchanger. Coolant will begin to trickle.


6) Open hood and remove Coolant Reservoir Cap. Caution: drainage changes from a slow trickle to full flow.




7) Place hose back on and secure clip.

These next few steps are taken from the Bentley Manual:
8) Open Coolant Reservoir Cap and bleed screw.


9) Fill until coolant starts to emerge from bleed screw. This will either be the standard 50/50 mix or your own. For track purposes in the warm valley, I used 25/75 coolant/distilled water plus two 24oz bottles of Water Wetter.
10) Close bleed screw.
11) Fill Reservoir to lower edge of filler neck.
12) Close cap and perform following to bleed system. Bentley recommends connecting a battery charger. I didn’t have one so I turned most evertything off to conserve power.
13) Switch ignition on.
14) Set heater to max temperature and turn fan to lowest speed.
15) Press accelerator pedal to floor for 10 seconds.
16) Bleeding procedue begins and takes approximately 12 minutes. (Electric coolant pump turns ON and OFF automatically). Caution: Do not open reservoir cap while pump is on.
17) Fill coolant tank 100ml above MAX
18) Check for leaks.
19) Replace undertray.

That’s it. Again, using this method results in draining approximately 1.25-1.5 gallons. AT vehicles have a 2.23 gallon capacity. MT vehicles have 2.17 gallons. If desired, you can complete a full flush. This will require the removal of your FMIC and eliminates steps 4-7. Instead, after removing the FMIC, you should find the radiator drain plug. Open and drain. Then continue on to step 8.

Regards.

[Syndicategt]

Great post Dan! Are you prepping for the track?

[tanginaglaz]

Awesome write up! I shall be doing this myself.

[scottp999]

Thanks! I think this is a good maintenance step if you don''t have a lift to make it easy to drop the fmic (especially if you have a bad back). Will add this to my yearly maintenance routine.

[Rotorocious]

Is that heat exchanger on M/T cars as well?
Don't remember seeing it.

[dbjb]

Originally Posted by Rotorocious

Is that heat exchanger on M/T cars as well?
Don't remember seeing it.

No. Just AT cars. One reason why we overheat sooner than MT is that the coolant lowers tranny fluid too.

[AlanAZ]

It's recommended to do the bleeding process twice. You will get some additional air out of the system with the second bleed. You don't want to risk an air pocket damaging the head.

[dbjb]

Took the car to Infineon yesterday. Temps were in the 80's. No limp modes and oil temps dropped much faster. In fact, after hitting an oil temp high of 285, it went back down to 255 by the end of the cool down lap. Once parked, dropped again to about 245. Happy with the results. Makes me want to remove coolant all together in this hot California sun.

[Syndicategt]

Good work Dan. I'll be doing this before I hit up Thunderhill in August. I can't beleive how hot your car runs, I didn't see oil temps above 255 yesterday. I'm accutally starting to believe the affects of methanol cooling the cylinders is causing my engine to run cooler, thus keeping oil temps down.

[hnekcivic]

one thing i just want to make sure that i read correctly, after fill with new coolant, close the bleed screw and cap then turn water bump on right ? im planning on do it soon ..good DIY btw

[rooringhusky]

Thanks dsbj!! I pretty much used this tutorial to help me partially drain my radiator...

Will do full drain when I get around to changing FMIC..

Anyways thanks again! Very helpful

[tanginaglaz]

I just did this earlier. One thing to mention is that the coolant sprays out when you open the hose initially. Wear eye protection!

[dbjb]

Originally Posted by hnekcivic

one thing i just want to make sure that i read correctly, after fill with new coolant, close the bleed screw and cap then turn water bump on right ? im planning on do it soon ..good DIY btw

Yes, that is correct.

Originally Posted by rooringhusky

Thanks dsbj!! I pretty much used this tutorial to help me partially drain my radiator...

Will do full drain when I get around to changing FMIC..

Anyways thanks again! Very helpful

Glad it worked out for you. Thanks for the kind words.

[bimmertt]

Anyone have a pic of what to use to drain on a MT?

[Transport3r]

Nice writeup! I'm doing this next weekend, thanks for the help!

[06white330]

Just curious but how does the air come out if both the bleeding screw and the cap are on?

[prelude2perfect]

Originally Posted by 06white330

Just curious but how does the air come out if both the bleeding screw and the cap are on?

That's what I was thinking too but somehow it works! This car was by far the easiest car I've ever done a coolant drain and refill on. I didn't even need to top it off after the 12 mins of cycling.

[NiVeDh]

Originally Posted by 06white330

Just curious but how does the air come out if both the bleeding screw and the cap are on?

It comes to the top I presume. When you open the cap afterwards, you may hear a hiss.

[Ben213]

Are these the same steps for e90 328?

[qpboi]

what about on a MT ? where to drain the coolant ?

[bimmertt]

Originally Posted by qpboi

what about on a MT ? where to drain the coolant ?

Need to remove intercooler and drain directly from the radiator.

[joeveto]

Hi everyone, I just completed this on my 335 MT. This is a great write-up. A few points I'd like to underscore:

1. For the manual transmission, you do not need to remove the intercooler. Looking up under the car, on the passenger side, you'll see a coolant hose going into the radiator. There is a clamp on this. You can loosen it, pull it, drain it, and then replace. Easy.

2. For the bleed: it's very important the key is in the dash, ignition on (i.e. headlights are on), and both temp dials turned to high (84 degrees). As stated above, push the accelerator pedal in for ten seconds or until you hear the water pump cycle on. Then let it go. I used this time to replace the undertray.

Thanks for a great write-up!