æ to reduce smoke emission
æ to heat up the incoming air
æ to reduce engine noise and vibrations
æ to improve drivability from cold
æ The pre-heating system supplies the additional heat energy which is required for a cold start.
æ Just before starting the engine a voltage is applied to the terminal of the glow plug and the current flows through
the coils of wire inside the heater tube. This heats up rapidly, the heat energy being transferred to the protective
sheath causing it to glow.
æ The time taken to reach sufficient temperature where stable combustion is attainable varies with different engine
æ The glow plugs continues glowing
after start-up to reduce the amount of white or blue smoke produced. As well as to eliminate any starting problems at
low temperatures. The post-heating phase is determinate on the engine temperature, as a cold diesel engine produce
more noise and pollutant emissions.
The correct way to replace glow plugs
Important on replacement: need to
observe the right tightening torque for
glow plugs and power connection nuts!
When replacing glow plugs, we
recommend you to pay special
attention on these main aspects:
1. Use the right wrench for the glow plug and terminal 2. Take care that dirt around the hole for the plug could not fall into the cylinder 3. Make sure that the glow plug is correctly inline with the thread of the cylinder head 4. The glow plug must be tightened to the correct torque 5. The power connection nuts need to be tightened to the correct tightening torque.
The glow plug could be damaged by using oversize torque. This could result in irreparable damage to the plug, as well as to the damage on the engine.
1. Fitting a glow plug with a torque
Please observe vehicle manufacturer’s specifications. Do not grease or oil threads! Caution – observe maximum torque settings: M 8 threads: 8-14 Nm M10 threads: 15-18 Nm M12 threads: 20-25 Nm
2. Fitting a glow plug without
a torque wrench:
Screw the glow plug into the cylinder first by hand. Then use a suitable ring spanner and tighten the glow plug for approx. 300. Do not oil or grease the thread.
3. Tightening the power connection nut:
The maximum torque setting for the power connection nuts must not exceed the following values: M4 threads max. 2 Nm M5 threads max. 4 Nm If glow plugs have pin connections, please check also these for corrosion.