As I understand it, glow plugs work by heating the cylinders to aid starting. Once the cylinder is hot, the fuel ignites by compression. Surely the engine heats itself by doing this over a few cycles - so do the glowplugs stay on throughout the journey, or cut out after a short period? I suspect that is the case, but how long would that be?
This refers to a Mondeo TD, but I also suspect that is circumstantial.
Thanks!
You should turn the ignition to the first position, see the glowplug light turn on, go out after a couple of seconds, then start the engine. The glowplugs are only on for the time that the lamp's on.
Many thanks!
The light doesn't come on, only the battery light, and that's dim. This is because she's been parked up for a few days and the area has frozen - I reckon the battery has drained. I'm going to try a jump start and take it from there.
Just a question I didn't know the answer to; I'm a self taught fool-with-the-tools!
M
Some cars have a fixed length time for the glow plugs to be on. Others have a variable time depending on the heat of the engine. They all go off after this time, some go off as the engine starts.
-- Malc
Not necessarily. A lot of diesels will run the plugs post start to aid the engine. The heating phase is also dependant on the head temperature - my Focus can want as much as 20 seconds of heating before it turns the lamp off indicating that I should start it. This is at about -20C in the Alps, in the UK during summer it wants only a few seconds.
The glow plugs do not heat the cylinder as such, they glow and have diesel squirted on them, the diesel catches fire and blasts the piston down, after a few repeats the engine starts and runs on its own, the glow plugs usually are kept heated for a length of time that varies with ambient temperature.
mrcheerful
My Mondeo TD (early 96) has the plugs on for 10 seconds regardless of the weather. Sitting inside you can hear the relay clicking at first turn and 10 seconds later if you don't start it. Tested the "plug rail" with a meter to confirm this.
Rv!
Your glow plug relay is faulty then- it should be dependant on external temperature- it uses the coolant temp sensor to determine this.
It should also continue glowing after engine start for upto 15seconds (very cold).
Tim..
Have something to add? Share your thoughts — no account required.
Ask the community — no account required