so what your saying is with stock tires I am now way over geared LOL.
Sounds like an installation error to me. A new clutch should not have an issue disengaging. They are blowing smoke up your ass. A new clutch installation
There are plastic gears which turn to control the vents. Likely one has broken (the gear tooth or teeth) and makes a clicking noise until it finally
Is it leaking from the front of the motor or further back? Check the radiator.