An improved seal and stabilizing system for a piston head in a tank cylinder provides a better mechanism for discharging and wiping a cylinder when heavy liquids such as chocolate or peanut butter are being dispensed. The seal system now includes a free-floating block inside the seal and grooves in the inner lower part of the hollow seal. The block and grooves keep the upper, outer part of the seal from deforming away from the inner surface of the cylinder that facilitates complete discharging and wiping of the material from the cylinder tank. The tensioning mechanism of the seal is made from a unitary and annular ring T-ring that easily slides on the rear surface of the piston head. In order to stabilize the movement of the piston head down the cylinder, clockwise and counterclockwise springs are provided for the stabilizing shoes. The dual spring arrangement prevents coil binding of the springs. The springs and stabilizing shoes maintain the piston head cross section parallel to the cross section of the cylinder.