Has anyone had this, my coolant surge tank (or reservoir) is looking like it’s cracked.  It’s not leaking but the only coolant visible is a little in the bottom. The tank is so fogged up I can not really see very well. So I assume it might of leaked out. Engine is not running hot I have the Cummins diesel 360 hp on a 2015 fleetwood expedition. The system is a sealed system so I have been afraid to open the cap. My guess is I need to bring it to Freightliner. Any comments. Thanks