With diesel-powered vehicle now under pressure, as sales fall and concerns are raised from environmentalists and politicians, ignition specialist NGK has issued some timely advice on the vital role that glow plugs play in maintaining engine performance and reducing emissions.

Glow plugs are generally not considered a service replacement item in an engine and no mileages or time recommendations for change are made by the vehicle manufacturers. Consequently, they are only changed predominately when a starting issue is present or if the engine management light comes on and the fault is traced to a failed plug.

Tim Howes, Deputy General Manager – Supply Chain & Technical Service, NGK Spark Plugs said,  “Because the glow plug is a vital part of the engine management system, as with most other components, it has never been more important to ensure that the installer is fitting the correct specification item. You cannot go for a ‘budget’ alternative nowadays because on-board vehicle diagnostics can pick up very quickly the fact that it is incompatible with the engine management system.” He adds, “The OBD system will find fault with the item if it is not to the correct specification and the performance of the vehicle will suffer. My advice is always to fit a plug that was manufactured to OE specification, as all NGK plugs are.”

Tim explains, “All NGK glow plugs are manufactured to OE specifications or above. Our ‘Fit & Forget’ philosophy means that we will only test specific parts against specific applications when we are absolutely 100% sure that they are entirely suitable for the vehicle. This philosophy is one of the reasons why NGK has been so successful not only with spark plugs but with glow plugs as well. Glow plugs are not like a spark plug where you can offer an upgrade. With the glow plug it has to match the OE specification which the NGK offering always does.”

Tim also points out that the demands placed on the glow plug have increased dramatically. He says, “The technologies that have evolved have been a direct response to increased demands. We are reaching the point where we are trying to get the temperatures up in the combustion chamber so very, very quickly that there is no discernible delay between putting the key in the ignition and actually starting the engine with little or no smoke emission, even at extremely low ambient temperatures.” He adds, “You have therefore now got several technologies from the standard metal glow plugs to the latest generation NHTC (New High Temperature Ceramic) types and the AQGS (Advanced Quick Glow System) plugs. Ceramic glow plugs, though a little more expensive, are increasingly being selected by the OEs because of their extremely short pre-heating and long post-heating ability in conjunction with an acceptable service life under particularly high duty cycle requirement.”