Glow Plug Warning light???

[pace]

Hi All,
The glow plug light on the dash of my 2003 ML 270 has started staying on after the engine has started.

It seems to stay on for about a minute after driving off and then goes off and doesn't come back on until I stop the engine and start again.

It has done this a few times in the last couple of days but not all the time.

I guess it is there to warn of a failed glow plug/s so it puzzles me why it is not doing it all the time?

Could it be a sticky glow plug relay? And if so could this cause the glow plugs to stick on and burn out?

Any ideas?

 

[umblecumbuz]

Apart from testing each plug with a multimeter, which is simple, have you checked over the wiring to each plug? On a Golf, we found a lead that had worn internally because another pipe was constantly vibrating against it - intermittent circuit.
Long shot, I know - but might be worth a look.

Baz

 

[bigbear]

Hi All,
The glow plug light on the dash of my 2003 ML 270 has started staying on after the engine has started.

It seems to stay on for about a minute after driving off and then goes off and doesn't come back on until I stop the engine and start again.

It has done this a few times in the last couple of days but not all the time.

I guess it is there to warn of a failed glow plug/s so it puzzles me why it is not doing it all the time?

Could it be a sticky glow plug relay? And if so could this cause the glow plugs to stick on and burn out?

Any ideas?

You have a glow plug gone,
VERY DIFFICULT to try and do yourself, best left to the experts.
I have been told glow plugs are not needed to start the engine these days more to mop up emissions

 

[rpe2]

If you do try to replace yourself, ensure the engine is as hot as possible before trying to remove.

Sent from my GT-I9100 using Tapatalk

 

[panason1c]

You have a glow plug gone,
VERY DIFFICULT to try and do yourself, best left to the experts.

Actually, the task of removing and replacing the plugs is very EASY to do yourself, (number 5 is a bit awkward to get to) just make sure the engine is at full working temp before loosening the plugs, as the downside is that they can sometimes shear and leave the bottom half of the glowplug still in the head.

Do a search on this forum for more detail.

 

[bigbear]

Actually, the task of removing and replacing the plugs is very EASY to do yourself, (number 5 is a bit awkward to get to) just make sure the engine is at full working temp before loosening the plugs, as the downside is that they can sometimes shear and leave the bottom half of the glowplug still in the head.

Do a search on this forum for more detail.

It depends on the level of expertise of the original OP.
There a quite a few things that could go wrong by saying it is easy and could cost more putting it right than it would have cost having it done by somebody who knows what they are doing.

 

[panason1c]

There a quite a few things that could go wrong.

Not sure how many things can go wrong in this particular issue?, i've changed the g/plugs twice on my ML over the years i've owned it and it is less than 1 hours time to do all 5.
Changing the glowplugs on a ML270CDI is as simple a job as changing spark plugs, access to the g/plugs is good (except for #5) and the only potential hazard is the risk of shearing of a glowplug, which is substantially reduced when the engine is hot. (the risk of a g/plug shearing applies to all levels of expertise)

 

[trousdale]

Same thing happened on my Eclass 280 cdi. main dealer could not get the old plugs out as they had seized into the block The light is still on and the advice the dealer gave me was leave it alone as the engine still starts. Not good

 

[panason1c]

Same thing happened on my Eclass 280 cdi. main dealer could not get the old plugs out as they had seized into the block The light is still on and the advice the dealer gave me was leave it alone as the engine still starts. Not good

Its possible (i stress possible) that the technician just drove your car into the workshop while it was still a cold engine, and went ahead to remove the g/plugs with the attitude 'they come out or they dont come out'

I replaced all mine very recently, and i tried to remove one with the engine cold just to see if it would undo, but it wouldnt budge with moderate force, but after i got the engine hot it undid very easily using less force than i did previously.......

There are good technicians and not so good one's and it's a sad fact that some dont take as much care as they should, anyway, removing the head to remove seized plugs is a good money earner.

The problem with leaving 'stuck' g/plugs in situ is that, apart from the annoying light always coming on, the old plug will build up layers of carbon on the tip over time, and this will make things even more difficult to remove the plug at a later date.

Plus, selling the car on with a g/plug problem isnt going to make an easy sale.

 

[Benz17]

Is the glow plug issue a common theme on mercs, I ask because on my two previous cars, a Vauxhall omega cdx, and a Volvo v70 tdi, I never had such issues, I always turned the engine once the light went out.

 

[panason1c]

Is the glow plug issue a common theme on mercs, I ask because on my two previous cars, a Vauxhall omega cdx, and a Volvo v70 tdi, I never had such issues, I always turned the engine once the light went out.

Not really an issue, I've done approx 100k between glowplug changes, i've always changed them all at the same time even though it might only be one of them thats blown. (my ML is currently on 220,000 miles)


ps......... My most recent g/plug failure caused one of the fusible links inside the g/plug relay to 'blow' which meant that even after i replaced all 5 plugs the g/plug light continued to show after i started the engine.........the cure, rather than buying a new relay, is to open up the 'sealed' relay, and 'piggyback' solder in another fuse over the broken link. It works perfectly again now.

 

[pace]

Thanks for all the advice. Going back to my original questions, why is the warning light only coming on sometimes? Surely if the problem is a failed plug then it would now be on all the time? I drove the car today and I think it only happened once, possibly when the engine was cold.

I have changed Glow plugs on a Vauxhall and a Ford before. It wasn’t a difficult job at all but they were both transverse engines. I would probably get my mechanic to do any work on this car as I don’t really have the spare time and he has much more experience with these cars.

Would this problem show up as a fault code? Be it a glow plug or faulty relay?

If the relay is sticking will I burn out all the glow plugs?

@panason1c, is your relay fix a mod or were you just trying to save the cost of a new relay?

My mechanic has said its probably best to ignore it if it doesn’t affect cold starting but I am more inclined to replace all the plugs and the relay if the cost is not astronomical as I like things to be right.

 

[pace]

Further to my last post, I used the car a couple of times today and the light is not staying on. So I'm a bit confused? Anyone electrically minded have any idea?

 

[rlden]

#5 Glo Plug

Not sure how many things can go wrong in this particular issue?, i've changed the g/plugs twice on my ML over the years i've owned it and it is less than 1 hours time to do all 5.
Changing the glowplugs on a ML270CDI is as simple a job as changing spark plugs, access to the g/plugs is good (except for #5) and the only potential hazard is the risk of shearing of a glowplug, which is substantially reduced when the engine is hot. (the risk of a g/plug shearing applies to all levels of expertise)

I have today replaced the 1st 4 g/plugs - the 5th looks very awkward and difficult to get to. I would appreciate advice in how best to change the 5th one.

 

[panason1c]

I have today replaced the 1st 4 g/plugs - the 5th looks very awkward and difficult to get to. I would appreciate advice in how best to change the 5th one.

Hi,
Access to #5 looks worse than it actually is........move the coolant header tank to one side (but dont disconnect any of its hoses), you then need to unclip the rail fuel pipe, thats in the way, and carefully move it to one side. Thats it really, you should find access is fine after that.

 

[rlden]

Thank You

Thank you very much, I'll try again this weekend and let you know.
Richard.

 

[panason1c]

Thank you very much, I'll try again this weekend and let you know.
Richard.

I forgot to mention, The bonnet can be raised to a near vertical position which allows better access to #5.......... If you open the bonnet and look in the area where the gas struts are connected to the bonnet you will see another 'spare' ball joint coupling a couple of inches away, just have a friend support the bonnet while you pop off the struts from their ball joints (using a screwdriver as a lever) and then refit them to the 'spare' ball coupling while raising the bonnet to vertical, dont forget to swap them back before you try to close the bonnet.