Originally Posted by mojoracing
Im surprised there was enough room to mount it over the existing one but I am unfamiliar with its design. Perhaps the volume of air the max fan is moving somehow creates vibration on the old one or the old one restricts flow and creates noise. I would remove the old one and just use the max fan and see if that helps.
Sorry, I think I posted the wrong fan in post #1. The correct fan is the Turbo/Maxx. The instruction states If you donít want to install a new vent, the fan unit will bolt onto the existing vent. i don't think it's vibrating off the old van cause I can hold the old fan and the noise makes no difference. I have attached a pix of the fan.