I just got a 13 f250 6.7 and have been going through everything to make sure everything is in good working order. I have noticed when I run my truck and shut it off I can hear and feel bubbling in the top coolant hose. I don't see anything in the recovery tank but it lasts for a few minutes and it's done. It's not running hot and I'm not having to add coolant. Is this normal for a 6.7? I had a 5.9 cummins before this and this motor is way more complicated than that one. Thanks in advance.