Traditionally, diesel engines have always been seen as noisy, smelly and underpowered engines of little use other than in trucks, taxis and vans. But as diesel engines and their injection system controls have become more refined, the 1980s have seen that situation change. In the UK in 1985 there were almost 65,000 diesel cars sold (about 3.5 per cent of the total number of cars sold), compared with only 5380 in 1980. Read more
To pre-heat the cylinder head and engine block before cold starts, the diesel uses glow plugs. They look like short, stubby spark plugs and are connected to the car's electrical system. Elements inside heat up very quickly once power is applied.
Glow plugs are activated either by an auxiliary position on the steering column switch, or by a separate switch. On the latest designs they automatically switch themselves off once the engine has fired and is accelerated above idling speed.