1995 325i mild overheat and now ...
 

My daughter drives a 1995 325i E36 I did the water pump thermostat and expansion tank about 3 months ago at about 125k. She calls me to tell me it’s stalled, It turns out the expansion tank cracked and she drove long enough for the car to stumble due to heat. I fixed the car on the side of the road with a new tanks and coolant and took it home. The vanos unit is now clacking, that noise like a stripped gear.

I have not overheated an M5x nor worked on any that have overheated. I know these engines can take a lot more heat than you would expect, but I think this one got damaged. My question is anyone overheated one of these engine and seen this failure? It looks like the manufacture of the tank is going to cover the repairs, but I am interested in that noise. I have heard it on 3 different cars (2 besides this one) and one turned out to be a camshaft bearing, the other was a vanos unit. Both those repair are beyond my toolbox skills, so I sent them down the road, anyone have experience with this noise? Or how to tell the difference between the vanos or cam bearing? I swear they sound identical.