glow plug light comes on after starting

[charliefarlie]

Am sure this has been posted before but cant find it, my C250 td has started recently in last few days after starting either cold or hot the glow plug light lights up after it has started , i get into the car put the inginition on the light for glow plugs comes up as normal then goes out i then turn key to start it does every time but then the glow plug light comes on again and stays on a good bit longer than normal or it seems that way it does it after being run and engine is hot , have had it on the computor analise thing it says its the glow plugs been told it may be the control unit , any thoughts has some one else had the same problem.
Thanks CF

 

[StevenN]

Sounds like you have glowplug/s that need replacing

 

[BTB 500]

Yup as above it's normally a failed glowplug.

 

[panason1c]

Best to replace them all while you're at it, the other plugs wont be far behind the failed one.

 

[charliefarlie]

thanks for replies ,Any particular make glow plug as have heard or read it some place they dont recognise cheapies too well the computor what else ooh i hate em .
cf

 

[StevenN]

The standard forum answer will be try eurocarparts.
Beru are the standard fit for MB
You may be able to see how many plugs are faulty buy doing a resistance check.
If you search the forum you will see many post in glowplugs
Mine included
You may decide it is a job for a garage as they are prone to snapping.
Good luck if you tackle it yourself
Remember soak them plenty and don't try to remove them from a cold engine

 

[BTB 500]

Best to replace them all while you're at it, the other plugs wont be far behind the failed one.

Depends on the age/mileage, surely. One failed on our Vito after 4 years / 35k miles ... hopefully the other 5 aren't about to go.

 

[charliefarlie]

Guess what it aint the glow plugs its the piece of electrical nonsense that activates the glow plugs why oh why do manufacturers make things so complicated and expensive , would be so much easier if they reverted to the older way of activation switch on ignition press a button wait five seconds start the engine , or use easy start if desperate .
Between the uncomfy seat and now this its good buy to merc cars for me had enough . Cf

 

[StevenN]

Hi Charlie do you mean the relay?
If its just that I would say its an easy fix compared to changing the plugs

 

[asauk]

I had he same issue with my c250 td, last month,
The advice was to change them all,
Follow that advice…
I changed them all, with the engine hot, and no issues..
Worth doing as its not complicated..

 

[charliefarlie]

Thanks all , problem now fixed took the easy route took it to garage where they put new glow plugs in then decided it was the relay , now it traspires it was just the glow plugs as they didnt clear the computors memory after fitting them , anyway phoned bells of coldstream merc agent to enquire price and availability for the relay was very pleased to hear a new one is only 103 plus dreaded vat , and as said is an easy fix if required now or later .
cf

 

[StevenN]

Glad you got it fixed and that they changed the plugs without hassle.
You would have really felt unloved if they had to strip the head.

 

[malcolmsmill]

I know its an old thread but these problems come up regularly.

most MB models use the glowplug light as a fault light for the imobiliser or security system

if when first started the light STAYS on.... its a glowplug or relay fault (one duff glowplug is acceptable... it stays on for 2 or more duff)

if the light goes out and then comes on again its likely an imobiliser/security error....... commonly wrong key, key not detected or lock not returning "secured" signal

 

[Terry_]

I know its an old thread but these problems come up regularly.

most MB models use the glowplug light as a fault light for the imobiliser or security system

if when first started the light STAYS on.... its a glowplug or relay fault (one duff glowplug is acceptable... it stays on for 2 or more duff)

if the light goes out and then comes on again its likely an imobiliser/security error....... commonly wrong key, key not detected or lock not returning "secured" signal

Really????

 

[219]

In the E250D I recently sold , the handbook stated that the glowplug light coming on when the engine was running was indicative of one or more glowplugs being faulty , or a fault with the control unit ( relay ) .

That car ( W124 ) has no immobiliser or security system , and the keys are just dumb mechanical things , so it does all rather depend on which car you have .

As with others , soak beforehand with penetrating oil , get engine plenty hot before starting , and go easy as you can still expect them to be difficult to come out . I got two to come out easily ; the other three were very tight , needing plenty of penetrating oil sprayed in and worked down by carefully turning the plugs back and forth rather than just forcing them .

Be sure to put some high temp grease on the new ones when replacing them .

 

[219]

Just to add , I would imagine that , all glowplugs being wired in parallel , a dead short in even just one would be enough to drain the current available to the others and stop them working , or cause either a fuse to blow or some other safety feature to cut in .

 

[Dieselman]

Glowplug relays have fusible links for each output.

I've never heard of the glowplug lamp being used for an immobiliser fault on an MB, a VAG car maybe.

 

[rajeshmb]

C350 2010 Estate

Hi

I just wanted to share my experience with Glow lamps.
Mine coil light has been flashing and staying on frequently and flashing when driving.
A few have failed but all 6 need replacing with the ignition controller.
All in cost with Labour £535.

Being done at a Merc specialist, I have not checked what Merc itself was going to charge as I needed it done, so the wife does not get stuck anywhere, but as usual sorry you will need to book it in in 2weeks time.

Raj