E300 TD glow plug light

[Gaz69]

Hi Guys,

I've got my E300 TD and still learning about the car. It's an excellent car to drive and so far I'm pleased.

Have noticed that the glow plug light comes back on when the car starts and goes out after a period of time.

Is this glow plug problem or something more serious?

Any advice would be brillaint.

Great forum by the way.

Gary

 

[David Pemberton]

Hello Gary

Probably means that one or more of your glow plugs has packed in. Gets to be more of a problem the more of them that die and the colder it gets.

The diagnostic section of this DIY thread might help, though for a different car the principles are the same.

http://forums.mercedesclub.org.uk/showthread.php?t=29074

Best wishes

David

 

[Gaz69]

Hi David,

Thanks, of to Halfords for a set of glow plugs. It's great the car can still start even if a glow plug packs up.

Thanks again.

Gary

 

[Parrot of Doom]

Your car will start even on 2 glow plugs (with a lot of complaining!)

Please note glow plugs on this engine is not a job to be taken lightly - do a search for more information.

 

[dieselman]

This should help.

Just get the engine nice and hot then proceed as follows.

http://forums.mercedesclub.org.uk/showpost.php?p=4221&postcount=2

If any plugs are stuck, just undo them a bit, then retighten them a bit etc...

Also try undoing them with the engine idleing as it keeps the head hot so expands the threads a bit and also blows out the carbon that has built up around the plug so is binding it in.

The plugs bind in due to not being fully seated so combustion gasses blow-by and cause carbon build up around the shaft.

 

[David Pemberton]

In addition to dieselman's list I also suggest that you REMOVE the old plugs using a torque wrench to unscrew them - set to the same figure as tightening torque. If they won't budge then you could test your bravery by upping the torque setting. I've read elsewhere on this forum that the shearing torque is 35 Nm.

 

[Parrot of Doom]

35 Nm.

Bit higher than that according to this

http://www.mercedesshop.com/shopforum/showpost.php?p=1677063&postcount=17

 

[David Pemberton]

85-90 NM - I stand corrected.

Would the threads in the head take this though? It would be right off my Richter scale of bravery to apply that force in situ.

 

[dieselman]

Not used a torque wrench for removal but have undone some very tight plugs. Tight enough to hurt my hands a lot.

Just keep undoing a bit and redoing a bit and squirting with release agent or diesel. Took me 2 hours to get three plugs out but well worth it as opposed to snapping them off.

Clean the plug orifices out afterwards to avoid the new plugs binding in.

 

[natsbass]

Hi can anyone help?
Cant figure out if I need a new thread, but I'll go with this and see what happens.
1998 C250 td sport estate.
I have had a new set of glow plugs but the light comes back on after turning ignition on. I have had a guy check the plugs and they are not at fault, but now at a loss as to why the light is still coming on.
Any ideas?
Many thanks Natalie.

 

[wireman]

Some of the glowplug relays have fuses inside them, if on is damaged by a plug fail the fuse needs repair as well as replacing the plug.
Check for continuity of the plugs (about 1 ohm) and for 12ish volts on the plug terminal when its energised, good plug no & 12v means a relay or cable fault.

 

[dirtymonkey29]

i have the same problem with a 1999 Vreg E300turbodiesel, just changed all 6 glow plugs and after i start the engine the glowplug light stays on. It was doing this before i changed them so i had hoped a new set of plugs would have cured it. I have however tested the black connector with 6 pins in, which plugs into the glowplug relay (on the right hand side) with my multi meter and i get no reading on pin 4. is the problem with the glowplug? or the wiring?

 

[dirtymonkey29]

 

[john wells]

Hi Guys,

I've got my E300 TD and still learning about the car. It's an excellent car to drive and so far I'm pleased.

Have noticed that the glow plug light comes back on when the car starts and goes out after a period of time.

Is this glow plug problem or something more serious?

Any advice would be brillaint.

Great forum by the way.

Gary

It's a heater plug that has failed. Just happened on my C250TD