Glow plugs on diesel engines help in maintaining the warm temperature inside engines to efficiently and cleanly burn fuel. These plugs wear out overtime and would need replacing. However, not all aftermarket plugs are the same and compatible with engine type and car usage. Here are some things you must check when picking a new set for your engine.
Size and length
Glow plugs come in many sizes. Make sure the plugs you pick are compatible with your engine's specifications. Check if the plugs fit your engine. Measure the length of the plug to see if it can be mounted on the cylinder head. Plugs too long are unsuitable because it would extend beyond the plug's compartment. On the other hand, short plugs wouldn't even heat the engine effectively. Also compare the length of the heating element. Plugs with longer tips tend to be warmer than plugs with short tips.
Speaking of warmer or cooler plugs, also consider under what type of weather you usually use your car. Glow plugs are supposed to aid engines by warming them up for ignition when it is still too cold. As a general rule, if you drive in an area where the weather is rainy, snowy, or just cold, the warmest plugs are the right ones for your engine for better morning heating. For sunny and warm weather where the engine is partly heated because of the environment, less warm plugs are the way to go.
Powerful racing engines can get extremely hot especially when pushed to the limit. On a smaller scale, tuned engines are also warmer than their stock counterparts. Because these engines are naturally at a high temperature, the glow plugs for these must be relatively less warm. Install plugs too hot and you might end damaging your engine because of overheating.