No, diesel engines do not have spark plugs.
Why Not?
Diesel engines use a different combustion method compared to gasoline (petrol) engines:
- Gasoline engines use a spark plug to ignite a fuel-air mixture.
- Diesel engines rely on compression ignition:
- Air is compressed to a very high pressure and temperature.
- Fuel is then injected directly into this hot, compressed air.
- The heat causes the fuel to ignite without a spark.
What Do Diesel Engines Use Instead?
They use glow plugs, not spark plugs.
| Glow Plug | Spark Plug |
|---|---|
| Used in diesel engines | Used in gasoline engines |
| Heats air in cold start | Creates spark to ignite fuel |
| Assists only during startup | Fires continuously during running |
| Located in combustion chamber | Also in combustion chamber |
- Glow plugs heat up during cold starts to help ignition when the engine and air are too cold for compression alone.
Summary:
- ❌ Diesel engines do not use spark plugs.
- ✅ They use glow plugs (especially during cold starts).
- ✅ Diesel ignition = compression-based, not spark-based.
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