General description The Laser Tools Water Pump Wrench is a specialized tool designed for use on older GM (Vauxhall/Opel) engines, specifically for adjusting the cambelt tension via the water pump. This wrench is also compatible with certain Chevrolet (Daewoo) vehicles. Technical specifications Size: 41mm x 1/2""D Material: Chrome Molybdenum Finish: Satin Equivalent to OEM: KM421A (J42492) Compatible engines: 1.2, 1.4, 1.4 16v, 1.5, 1.6d, 1.6 16v