STILL overheating?!

[Grrrimacloud]

We have a 2000 740il. A few weeks ago we cracked the radiator (long story). Soon after, the car started overheating. On my way to work one morning it overheated and I heard a loud pop. The coolant reservoir had blown apart. Since then we have replaced the reservoir, radiator, radiator shroud, t hose, bleeder screws, upper hose, thermostat, and water pump. Yet it's still overheating. It's not showing any of the usual signs of a blown head gasket. Also, we changed the upper hose tonight and when we lifted the hood, we found the old upper hose was flat instead of round, almost like it had been suctioned flat. Based on my research, we will try to bypass the heater tomorrow and see if that works. Any other ideas in case it doesn't? I'm really quite frustrated at this point. Any help at all would be appreciated

[cyclops2]

sounds like air in the system. What is your experience bleeding the infamous e38? they are difficult and there is a very specific procedure.

[Grrrimacloud]

I knew I was forgetting to mention something, lol. We had the mechanic bleed it before he put the water pump on in hopes maybe that was the culprit. No such luck

[carnut1947]

A collapsed hose is a sign of low coolant. You have air in the system.

[Ruskii]

+1 on bleeding. I've owned few different BMW models that utilize expansion tank right next to/level with the radiator, and all of them were a hassle to properly bleed the system.

[acspecialists]

+2 on bleeding. I was at the track and blew my upper hose. After I repaired it I used Timm's method and had no problems driving home.

[Narlift]

Check underneath the oil filler cap when hot, hows that look? Black?

[Timm]

Here's the procedure:

https://www.meeknet.co.uk/E38/E38_Bl...ing_System.htm

Also, if you haven't - replace the expansion tank cap - it has a pressure relief valve fitted in it - nothing should pop or explode if that is working correctly