E61 530i Vanishing Coolant

[RanchoGrande]

Parked up my car on a slight incline over last weekend and didn't move it for 2 days; started it up and found the coolant level low warning on the dash. Checked the coolant and it was totally empty! Filled it up, drove home and it's not lost any since.

Any idea how this may have happened? Seems a bit odd as I would have thought it would continue to leak of a hose or something had split.

[d_a_n1979]

RanchoGrande said:

Parked up my car on a slight incline over last weekend and didn't move it for 2 days; started it up and found the coolant level low warning on the dash. Checked the coolant and it was totally empty! Filled it up, drove home and it's not lost any since.

Any idea how this may have happened? Seems a bit odd as I would have thought it would continue to leak of a hose or something had split.

Have you refilled it and bled the system to see how the level stays after that?

It could be that it's dried off or boiled off on the heat of the engine

Have a good look under the water pump bottom, it could be leaking from there & hard to see

Either way; refill, bleed, get engine up to temp and then have a good look for any leaks/hairline fractures in the rad/pipe connections etc

[RanchoGrande]

Thanks for the reply. I filled it back up and drove home which was around 80 miles or so which means it would have got back up to temp. I haven't bled it as I don't know how!

[d_a_n1979]

RanchoGrande said:

Thanks for the reply. I filled it back up and drove home which was around 80 miles or so which means it would have got back up to temp. I haven't bled it as I don't know how!

Easy; front end up higher (so drive it onto a block or jack it up slightly

Start engine; heaters to full, blowers to full, have header tank cap off and open the bleed nipple

Let the coolant flow and when it starts to get up to temp, hopefully you'll see either some coolant coming out with air bubbles, or if its a steady stream, then there's no air in the system.

Cap back on, bleed nipple tightened and let the car idle whilst its up to temp; check the cooling system for any leaks/hairline cracks etc... You could do this before you try and bleed it. If you see any coolant leaking (rad, top/bottom hoses & their connections), from the bottom of the water pump, from the stat etc), you need to get that part replaced ASAP

What year is your 530i?

[RanchoGrande]

Thanks, it's a 2007 N53

[helix402]

RanchoGrande said:

Thanks, it's a 2007 N53

If you want to bleed that is has a self bleed cycle for the electric water pump which is activated by diagnosis software or a special “press accelerator so many seconds” procedure.