I had this same problem in my new Montana 5th wheel with the Lippert Leveling system. Lippert send me a fix by replacing some of the hydraulic fluid. But that had no effect. I soon figured out that with the temperature changes the metal was expanding and contracting and possibly there was slight ground movement which was creating the pops. I then found the Pad Food RV pad on Ebay. I put one under each jack pad and have not had any more problems since. The rubber jack pad absorbs any movement eliminating all pops and creaking noises.