What do you mean he does not drop when he urinates?
Not all gelding let every thing hang out or as far as others do.
It would not hurt to take a sample of his droppings to the vet to get tested and if everything checks out okay but he is still "runny" you could always try a feed trough supplement.
A friend of mines gelding had a similar problem, nothing wrong with him he just has very wet poo so she started him on a supplement and it fixed it. I will have to ask her what it was she uses and get back to you.
This may help you out as well :) Chronic Diarrhea & Digestive Health - Diseases & Conditions - SmartPak Equine