Bleeding the cooling system

[jamesdc4]

There are two methods of cooling system bleeding that are generally accepted. The first being the "BMW/Bentley Manual" version and the second is the "Jim Cash" version.
I recommend using the former to begin with and if you still end up with problems, you may want to try the latter version. Be aware that the Cash bleed procedure involves some steps that require you to run/warm up the engine. This means the coolant can be very hot, so, if you try this version, use caution when opening the bleed valve.

BMW/Bentley version with embellishment and video by NNY528I.

Cooling System Bleeding (I6 w/video)

1)With the car cold and NOT RUNNING, turn the key to the start position, adjuster the heater to highest heat setting

2)Now bleed the system at the bleeder screws till no air comes out. First at the Thermostat cover then at the expansion tank.

3)Next top up the expansion tank to the cold fill level and close up the system tight.

4)Run the car till it reaches normal operating temperature then shut it off again and let cool to ambient temperature(several hours minimum)

5)Finally with the car completely cold check the level in the expansion tank, if normal, you should be finished, if low then repeat procedure from step 3 and fill to normal cold fill level and repeat the heat to normal temp and cool off cycle until the expansion tank stabilizes, then fill the tank to the correct level and you should be good to go.

DO NOT OPEN THE RADIATOR CAP OR THE BLEEDER SCREWS IF THE ENGINE IS EVEN A LITTLE BIT HOT OR RUNNING(even if cold)! you will ruin all your work and have to start over from the beginning of the instructions I provided above.

Jim Cash version.

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http://www.bmwtips.com/tipsntricks/JC/Overheating.htm
Over Heating Check List
by Jim Cash on 2002-11-04
I would suggest checking the coolant, and making sure it is bled properly - which can be a rather involved process to do it correctly.
The basics
Cold engine
- check that coolant level is correct
- Ignition on but engine not running
- set heater temp settings to max
- set fan manual to one of the lower speeds
- start engine and within 30 seconds rev it 3-4 times up to 3000rpm
- shut off engine before end of 30 seconds (before it starts to heat)
- reset climate to normal settings
- recheck coolant and top up if necessary.
Hot engine
- take car for a run to get up to operating temp
- using caution - slowly open the bleed valve (steam and bubbles may come out)
- close as soon as you see liquid coolant without excessive bubbles.
- do not overtighten this as they are plastic threads. Just snug till it seals fully.
- after engine cools check the coolant level again and top up if necessary.
Check coolant level every few days for a few weeks and top up again if required
- repeat the Hot engine bleed process again.
If coolant keeps droping after 2-3 top ups have the system pressure tested.
If you are still getting over temps have it analysed by a dealer. The temp is controlled by the engine computer so there may be another fault.
Cheers
Jim Cash
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Parking on an incline or raising the front of the car, as mentioned in an earlier post, is also helpful when trying to bleed the cooling system.

(Special thanks to NNY528I and cnn for their help.)

[eastman]

James,

Does the 540i have a bleeder valve, other then the one on top of the expansion tank?

thanks!

[dontknow17]

I'm confused, this may be a stupid question. In order to get the coolant to rise to the level of the thermostat bleeder I have to massively overfill the reservoir thus turning it from an expansion tank to a pressurised vessel waiting to pop. How do you get the coolant to bleed without overfilling it?

[528in]

I'm confused, this may be a stupid question. In order to get the coolant to rise to the level of the thermostat bleeder I have to massively overfill the reservoir thus turning it from an expansion tank to a pressurised vessel waiting to pop. How do you get the coolant to bleed without overfilling it?

You have to turn the key to the ON position but do not turn on the car. Once you do that turn the knob on the center of the dash were the two air vent are from blue to red. Then put the temperature on both sides to high. This will kick in the secondary pump that will create coolant flow. That is when you can bleed the system from the bleeder screws.

Sent from my Nexus 6P using Tapatalk

[Shelley73]

On top of reserve tank use screwdriver in the scored place on the cap and let run and bleed off. Keep eye on your temp while bleeding off. If that does not do it because not working properly put front of are on jack stands fill reserve tank up and leave top off or loose in reserve tank. When it quits bubbling air it is done.

[Olly84]

Just replaced my cooling system and bled the system properly. Yes you will have to overfill the expansion tank in order to get all the air out of the bleed nozzle, but simply suck the extra coolant back out of the expansion tank with a turkey baster till the float returns to the correct level and you'll be done. Car has been running fine for the last 2 days with A/C on and wide open throttle on the freeway.