Glow plug light

[amolak]

Hi,
When I turn the ignition key to no2, the glow plug light goes out as normal after a few secs.
However when I start the engine it comes back on and stays on for about 20secs, before going out.

Is this normal?
The handbook says that the light should not come back on when the ignition is started.

thanks
Amolak
V220 2000

 

[jimti]

when my w210 did that it needed 3 new glow plugs..got them all done at the same time tho

 

[silverarrow]

yep glow plugs change all of them ie when one goes the others are not long behind change them soon glowplugs needed when it is cold £15 plug and 1 hrs time no need to reset obc

 

[amolak]

I've heard some horror stories that the can seize and break in the head. Is this true?
My car is 4yrs old. 86k
tx
Amolak

 

[dogan124]

Hii,

I faced the same problem few months ago and infact had additional troubles afterwards (alredy posted at problem 1/3 : hard start up). While I had the faulty plug changed the mechanic told me keeping with a faulty plug might cause further and costy problems for new engines (I remember he mentioned about vitos), hence be replaced as soon as possible.

Hope nothing goes wrong with yours

 

[amolak]

Strange though as my car starts/drives perfectly with no problems.
I'd hate to replace items just cause a light comes on for 20secs.

cheers
Amolak

 

[SimonsMerc]

Strange though as my car starts/drives perfectly with no problems.
I'd hate to replace items just cause a light comes on for 20secs.

cheers
Amolak

I have the same thing on mine, started about a month ago. I decided I'll leave it till the service (another 5.5k miles) and get it done then.

 

[Dieselman]

Strange though as my car starts/drives perfectly with no problems.
I'd hate to replace items just cause a light comes on for 20secs.

cheers
Amolak

It will. A direct injection diesel doesn't really require glow plugs.

 

[amolak]

So why do they have them then?
Since the temp has been in the minuses lately, I think I'll wait and see what the light does when temps go up.
cheers
Amolak

 

[Dieselman]

Errm.

It'll do exactly the same. Glowplugs don't self heal in higher ambient temperatures.

Glowplugs on Direct engines have more to do with emission control than actual starting, unless it gets really cold.

 

[amolak]

So are glow plugs still used when the car is running?
I thought their only use was to start the engine up.

Amolak

 

[Dieselman]

For about 30s to 1min depending on ambient temperature.

The light on the dash is the pre ignition or preglow light. After ignition they are in the post glow stage.

 

[amolak]

Oh, so once the engine is started the car dont use the plugs. What did u mean about emission control then?
Srry to keep asking, I've never had a deisel hence dont understand the workings!

Amolak

 

[Dieselman]

When the ambient and engine temperatures are low the glow plugs stay on to ensure a full and clean burn of all the diesel.
After a short time the glowplugs switch off.

This reduces emissions.