I recently changed my radiator hoses and coolant (E46/325i). The lower hose connection to the radiator was akward to install from top and I did not get it all the way on - I thought I did ... but did not. I went on test drive and all was OK. Then a few days later, I drove into town and on the way home the water temperature gage went into red and the radiator light came on. I was 3 miles from home and drove home slowly (in hind sight I probably should not have driven). I found the lower hose disconnected. I let engine cool for a hour, refilled with antifreeze and all seems well - but I'm worried I may have caused some damage. Any thoughts?
BMW's do not take well to overheating but it sounds like you may have dodged a bullet. Keep a very close eye on coolant levels making sure the reservoir is full then in the coming weeks see if you notice any coolant use which would indicate a overheating related problem. If not you are good to go and can mark this one up to, like you said, lessons learned. Enjoy!
Maybe its just me, but from my reading several stories, it seems the M54 is a little better at dodging that bullet when the temp hits the red. Good luck, I hope all is indeed well.
Be sure to frequently check your coolant and oil for cross contamination. If you cracked the head or cause a head gasket failure the contamination would be a sure sign. I hope nothing bad happened...GL.
I've once had that happen in my E30, except in this case, it was a failed hose. I also had to drive to my destination when the temperature went south on me. Nothing really happened after about a mile and a half of driving with no throttle, though the temperature hovered just before the red zone. It has probably been about 20,000 miles since. If it's driving fine, then it might just be undamaged... hopefully.
