Abstract: A windshield repair device comprising a vacuum cup with a built-in piston and cylinder assembly is characterized by a transverse opening in the cylinder so that when the piston is partly withdrawn, gas bubbles can be drawn out of the repair liquid by the vacuum holding the cup in place against the glass. In operation, after the bubbles are removed from the liquid, the piston is moved toward the glass. The piston closes off fluid communication through the transverse opening in the cylinder and as it moves further toward the glass, it forces repair liquid into the damaged area. The invention permits the cylinder itself to be used as a reservoir for repair liquid, while allowing gas bubbles to be removed from the liquid by the vacuum holding the cup in place.