Only one reliable way, replace it. Since it is flexible, any repair made would be only a short lived repair, then, you still have to replace it, and fix any subsequent water damage.
Not the answer you would like, but, best in the long run...
Back to a 5'er after 4 yrs fulltime.
Pulling with a '14 2500 ram, 6.4 Hemi.
Montana High Country 31RE