Glow plugs

[BMACF]

Are glow plugs important once the car is started, and if so, what happens when they are worn or no good anymore. Do they make the car run a little rougher than usual? will it cause a loss of compression?

Thanks,
BMACF

[burn_your_money]

I doubt they would cause a loss of compression.

[Sonjay]

Glow Plugs Aid in cold starting and warming up the engine and air...

Because diesel engine dont have sparkplugs, the air is heated by compressing it, so when the fuel is injected it blows, burns fast, thats why diesel engines are louder because of the explosion.

The glow plugs will heat up the air and help start you car when it is not warmed up... and also could aid in running the car...

there is a glowplug for every cylinder...

[burn_your_money]

Testing glow plugs

Disconnect the engine temp sensor. connect an ammeter in sesires betweenthe glow plug bus bar and the wire which connects it. Turn the ignition on, for a maximum of 15 seconds, and notice the current measurement. After the initial surge, the total current shoudl drop to 48 ampers (12 per plug). If the current draw is not steady, or is less tehn 48, one ofmore of the glow plugs is faulty. To find the faulty plug, remove the bus bar and repeat the previous test measuring current flow to each indivual plug. Replace any plug that is drawing less then 12 amps.
The previous test they are refering to is as follows
Disconnect the wire fomr the glow plug bus bar, and remove the bus bar from each of the glow plug terminals. Connect one probe to the batteries + terminal and the other end to the end of each plug, one at a time.

Special thanks to Bentley. Hope this helps.
Oh yeah, this is for an A2, but it should be similar.