Glow Plugs

A glow plug  is a heating device used to aid starting diesel engines. In cold weather, high speed diesel engines can be difficult to start because the mass of the cylinder block and cylinder head absorb the heat of compression, preventing ignition (which relies on that heat). Pre-chambered engines use small electric heaters (glow plugs) inside the pre-chambers. Direct-injected engines have these glow plugs in the combustion chamber. The glow plug is a pencil-shaped piece of metal with a heating element at the tip.