Another busted reservoir tank

[TonyVA]

Ok, I am at my wits end! Driving yesterday (2001 X5 4.4i) I saw smoke coming from the engine compartment, pulled over and shut it down. Not surprisingly the seam on the reservoir had split. Towed it home, ordered the new one pulled it into the garage and installed it...20 minutes being careful with the hoses. Now here is my challenge...bled the system with BMW anti until there were no bubbles. I will do it again in the AM, however, where I am out of answers is the temp gauge stops right about where I figure the temp should be and then blasts over to the RED! Take the fluid temp and I am hovering around 170 F. So why is my gauge stopping for about 1 second at the correct temp and then slamming to the RED? Need help, anyone?

[X Wife]

My temp gauge on my 2001 3.0 does the same thing--goes from cold end of normal to HOT. I've stopped, pulled over and put my hand on the hood and it's barely warm, definitely not overheating. My non-BMW mechanic has an X5 too, same year/model as mine, and he mentioned his does it as well.

[JBEurotech]

there is a tsb to reprogram the dme for that issue

[TonyVA]

Thanks for the tips...went back to the drawing board, shook it several times side to side and up and down...burped it again and again until it settled normal. It was air in the system which initially is what I was thinking but this has been the most stubborn BMW I've ever worked on in terms of the cooling system. I've done my M and my 7 in the past without event. Thanks to all that helped!

[crasshh]

When filling up te anti-freeze/coolant in reservoir, follow the filling instructions to the tee. DO NOT overfill. The pressure wil cause the seal to burst if you overfill.