Was going to check the coolant level and the general condition of the fluid. Liftet the level pin gently and it just detached itself from the base. When looking at the part diagrams its doesnt seem possible to dismantle the expansion tank. The hole is to small to get the base through and its hard applying enough force on the pin to put it back down when the base is floating around.

 

When that stem detaches from float the tank plastic cracking and failing is never far behind. You need to replace the whole tank to be safe. Fussing with the stem and trying to stay will be a waste of time.

 

Had this happen to me. Its time to change the expansion tank. When it happen to me I changed the water pump, thermostat, coolant temperature sensor, and tank. I bought a water pump kit from am-autoparts.com and made sure they had the right expansion tank in the kit. Its been two years and water pump has not failed yet. The kit was only $171. It took about an hour to do the pump and tank. everything else only takes minutes. Now they are backing there products with a 10 year warranty.

 

Just replace the tank. Behr is the OEM for BMW. I'm not sure about the cost of parts in Norway, but it shouldn't be more than ~150 Euros.

 

Ok tnx.
I guess i wont be able to do it without letting air into the system?

 

I would think you should be able to drain enough coolant to empty the overflow tank and then replace and refill - that is what I was going to do since my pin detached too - probably no harm in doing the air purge with the water pump.

 

I doubt it lets air into the system to change the tank. But, I'd perform the purge procedure anyway.

 

Uh oh. My level stick broke 4 years ago...still on the same tank and all is well. What is your definition of "not far behind"

I saved the stick and place it in the tank to check coolant level and then remove prior to replacing cap.

 

I went to check my coolant level about a year ago and the pin was missing

I guess it's either stuck at the bottom of the expansion tank or has been banging around in my engine for 40k miles....

 

S.... is hot in there

My stick broke will be replacing expansion tank soon