coolant level problem (again)

[guinness]

A few weeks ago I posted about a coolant level message, well it's back and after looking at the cap on the expantion tank I think that I'm an idiot!! I took a good look at it today and saw that it was cracked and missing an O ring.
I replaced the cap and bleed the system (no air) any thoughts if this could fix the problem??
Jim

[Kalevera]

Well, having a working cap is critical for cooling system performance....

I'm surprised the thing didn't blow coolant all over the place the first time it was shut off hot.

best, whit