Bleeding Coolant

This past weekend I drained and refilled the coolant in my 2001 325i. During refilling I kept the bleeder valve open, expecting to eventually see coolant come out bubble-free when the system was full. This never happened. I measured the amount of coolant I drained, it was around 6 liters. I added about 6 liters back and the coolant level meter read full. No coolant ever came out of the bleeder valve.

I ran the engine with the heater on until it reached operating temperature. I then let the engine cool completely. I removed the coolant reservoir cap to find the coolant level meter sitting at the bottom of the reservoir, indicating the need to add coolant. I then opened the bleeder valve. When I opened the bleeder valve I heard a hissing noise. As the hissing continued the coolant level meter began to rise. When the hissing finally stopped the coolant level meter was reading too full (the float was being restrained by the plastic ring).

I closed the bleeder valve, replaced the coolant reservoir cap, and ran the engine again with the heat on until it reached operating temperature. I again allowed the car to cool completely (I let it sit overnight). The following morning I found the same result. I opened the coolant reservoir to find the float sitting at the bottom. I opened the bleeder valve and I heard hissing. As the hissing continued the coolant level meter rose. When the hissing finished the coolant level meter read too full.

Does anyone know what I should do in this situation? Should I let the engine cool completely and just add more coolant until the float reads correctly? Or is it already too full?

Are you supposed to add coolant with the bleeder valve open? If so, I probably added too much...

Any help is appreciated!

I think you're okay. For some stupid reason BMW had re-designed the radiator reservoir on the E46 to be dramatically different than the E36, which has a semi-translucent tank and a simple, functional bleeder valve on top that bleeds out fluid as you overfil. The way the E46 tank is designed, the bleeder valve sits on the hose that leads into the engine block side of the reservoir and it's impossible to tell if it's actually properly filled up unless you've got the engine running, heater going full blast. If you've already done that part and now the level seems a tad low, I wouldn't worry about it.

Sounds like you went through all the proper steps anyway. If you drained 6 liters and put back in 6, you're fine.

Per Bentley.

Refilling:

Reinstall radiator and engine block drain plugs

Before refilling radiator - switch ignition to on, set temp settings to full warm, blower control to low

Fill expansion tank slowly. Fill until coolant emerges from bleed screw.

Bleeding:

Loosen bleed screw.

Set temp control to full warn, set blower to low and turn ignition on, do NOT start.

Slowly add coolant until it spills from bleed screw. When coolant spilling from bleeder is free of air bubbles tighten screw.

Run engine until it reaches operating temp.

After engine has cooled recheck level
Top up so that coolant level is at max.



that is it.

Tim