It sounds like the silicone isn't setting right in your fan clutch and I'd return it. A question, does your fan normally make a lot of noise at startup? If so, and you'd like to eliminate this and increase cooling a little bit, order the fan and fan clutch from TSB 07-07-98 that addressed this issue. It says to use fan 52027709 and fan clutch 52029767AA. These are from the V-10 and the fan has a slightly different pitch for reduced noise and the fan clutch works differently to eliminate the fan roar at startup. It also increases the cooling ability of the system for your engine. Some folks have said they've done this with the stock shroud, there's a different shroud listed for the 4x4 and the 4x2 setups in the TSB. The complete story is in our operational section of Just 'D' FAQ's on the DOC home page (not on the forum's FAQ page.)
I did this early on for my D as it didn't cool very well and what a difference it made.