If your coolant level drops while you’re driving but comes right back when you shut the truck off, you’re NOT losing coolant.You’re being pressurized out of it.This is a critical warning sign we see on heavy-duty diesel engines—especially Detroit DD15s—and if you keep driving it, it can quickly turn into a five-figure engine repair.In this video, I explain:• Why coolant drops only while driving• What pressurization really means• How ignoring it leads to major engine damageIf you’re seeing this s