Glow plug warning light

[MTaylor]

I have recently bought an E320 CDI estate 2001, (is this what they code a W211)? The glow plug light illuminates as the ignition is turned on, and goes out after a second or two, but when the car is then started the light comes back on after a few seconds, and stays on for about 30 seconds. This happens especially when cold. Eberything seems OK, and there are never any problems starting the car. Should this happen or is this a sign of the plugs beginning to fail?:

 

[Andy Cottrell]

Hi,

This (usually) indicates that one or more glow plugs have expired. Since you have common rail injection this doesn't usually present too much of a problem as you've found. I waited for warmer weather before replacing mine ( on a 220 cdi) admittedly.

Hope this helps,

 

[316cdi]

My sprinter has been like that for 2 years still starts first time every time no matter how cold,it is a glowplug down

 

[MTaylor]

Thanks for the info - I'll get them replaced.

 

[JohnnyGurkha]

Hi,

This (usually) indicates that one or more glow plugs have expired. Since you have common rail injection this doesn't usually present too much of a problem as you've found. I waited for warmer weather before replacing mine ( on a 220 cdi) admittedly.

Hope this helps,

Andy,

Was it expensive?

Johnny

 

[Blobcat]

I have recently bought an E320 CDI estate 2001, (is this what they code a W211)? The glow plug light illuminates as the ignition is turned on, and goes out after a second or two, but when the car is then started the light comes back on after a few seconds, and stays on for about 30 seconds. This happens especially when cold. Eberything seems OK, and there are never any problems starting the car. Should this happen or is this a sign of the plugs beginning to fail?:

E320cdi from 2001 will be a T210. The 211's did not start until 2003. (W = Saloon, T = Estate)
as per others when glow plug light comes back on after starting then one or more of the glow plugs needs to be replaced. Not a large job as they can be replaced without taking the manifold off on this engine. However they have an annoying tendancy to break off when trying to remove them so proceed with caution. There are quite a few threads on glow plugs so have a search around.
I had No.1 replaced in January and the Plug was £12.18 and £67.92 to fit it + VAT at an MB dealer. I have just done 1,000 miles in last 3 days and the damm light has come back on so another one has gone. On the plus side however only 3 have failed in >100K miles.

 

[JohnnyGurkha]

Not a large job as they can be replaced without taking the manifold off on this engine. However they have an annoying tendancy to break off when trying to remove them so proceed with caution. There are quite a few threads on glow plugs so have a search around.
I had No.1 replaced in January and the Plug was £12.18 and £67.92 to fit it + VAT at an MB dealer.

So Blobcat, is this a job not to be attempted by an amateur? You made it sound easy to replace, but then got a garage to do it. Sorry if I am being thick, but could you clarify pse?

 

[Blobcat]

Hi Jonny,

Like most jobs it can be easy or it can be a right *******.
I weighed up the £95 inc vat against my time. Check out this thread http://forums.mercedesclub.org.uk/showthread.php?t=9776 for futher glow plug fun

 

[steve kane]

Does anyone know if its better to attempt to remove Heater Plugs with the engine hot? the Mercs have an Alloy Head and Steel Heater Plugs and I would think its perhaps best to get the engine good and hot first before trying to crack them out, and perhaps a smear of Coppaslip on the new ones when fitting?, anyone have any views on this?
Steve.

 

[psmart]

Hi Steve, MTaylor et al

Please read the my posting on thread http://forums.mercedesclub.org.uk/showthread.php?t=9776&page=2

After a chat with MBenzNL, the main problem with glow plugs is under-tightening (besides weak design). When you undertighten them, gasses (miniscule) can leak out, and as a consequence, you get carbon build up, which is what really does the damage and stops you getting them out.

MBenzNL and Mercedes use a white sealing compound on the flange when they put new Glow Plugs in and they over torque them.

You can buy a kit to drill them out from a German company called Kreuze-Werk, but at EUR500, you should club together to make it pay!

 

[Bolide]

Glow plugs

Replacing glow plugs is straightforward but if you've never done them before it's difficult to know if you're about to snap one

On that basis I'd say it's not a diy job with a sufficiently high success rate for me to recommend you do it at home

I'd go further and suggest you get an expert to do it and insist they don't let "the boy" do the job. The downside is just too expensive!

Nick Froome
www.w124.co.uk

 

[JohnnyGurkha]

You have all just convinced me to spend my money wisely at the dealer rather than getting my fingers dirty. However, I seen a number of quotes for glow plugs at £12+vat, yet I have seen them at less than £7 (incl vat) each from GSFcarparts.com. I assume there is little difference in quality?

 

[steve kane]

Glo Plugs

Goodness that was worth reading, lets hope I dont have to replace the glo plugs! just as a BTW I have always found Plus Gas to be an excellent Penitrating Fluid, though on a good hot engine it might vaporise off and need topping up.
Steve

 

[steve kane]

GloPlugs,

Many thanks for the info, thats really usefull to know, just as a BTW I have allways found Plus Gas to be the best Penetrating Fluid, and has allways been highly effective (not tried on Merc Glo Plugs though!!), however on a hot engine it might need topping up as it will vaporise.
I noted the stuff about Glo Plug Resistance Values, and its my experiance that they are either alive or dead, ie if you just check the continuity of each Plug (obviously with the buss bar disconected, terminal to earth) then a reading shows the plug is still working as the element is still intact, no reading and the plug is definately shot, Im sure it can be made more tecnical than this but in essence I think thats really all there is to it.
On a slightly different tack, I was mystified by a VW Golf which had knocked out a set of Glo Plugs one by one, these were replaced with a set from German & Swedish which only lasted a few months, when I checked I found that after starting the Glo Plugs were still running and I thought this was the problem, the Main Dealer Electrician suggested a Relay Problem which it was not and then offered an open ended and no doubt expensive investigation which I recoiled in horror from, then a little while later and on another matter entirely I was looking at a VW POLO Haynes Manual where I noticed that they said that the Polo Heater Plugs came back on for a short while after the engine started to assist Emisions!! I reconected my Golf Glo Plugs and found just that ie "live" with Ignition On, then "off" with the Dash Heater Light, car starts and Glo Plugs came back on for a minute or so with No Dash Light Showing, the set of Plugs from German & Swedish were just a duff set and all was okay from then on, this type of thing does not give one much confidence in the Main Dealer Network either I think!!
Sorry its so long winded, but I wonder if some Mercs also use this Heater Cycle?
Steve.

 

[psmart]

Hi Steve,

Please excuse the length of this post, but its needed to explain why I gave the resistance values, as it could help to detect a problem. I agree, you would normally expect the glow plug to go open circuit when kaput.

On the 270 (and I assume most later models), the Relay is a combination of Micro-controller plus Relay. Without disecting the micro-controller, bypassing its security and disassembling its software (an illegal act), I cannot say for 100% certainty that my assumption below is accurate, but if you've gone to the trouble of building a micro-controller into something, you would generally expect to use its intelligence to detect faults.

In electronics, components age and their characteristics change along with manufacturing faults which may take years to show up. A glow plug is a resistor, and it outputs heat according to the voltage input and its resistance (ie. Current flowing through it is dependant upon Voltage and Resistance + other criterion, such as temperature).

I was told that the resistance range of these glow plugs is between 0.5 to 1.0 Ohms, which seems to concur with my readings, but Im sceptical, because a 0.5Ohm resistance at 12v is 200+Watts of power, which seems a little high for 1 glow plug.

If the designer of the engine required a minimum of 100Watts of power to ensure engine starts correctly, or meets its emission targets, then the glow plug must not have a resistance above 1.45Ohms. Thus, its logical to assume that the micro-controller, through voltage drop, detects if the glow plug resistance is too high, and warns you.

On the other side, the Relay contacts are only rated for a specific current, say 30Amps (example), which would be within limits for 12v-14.4v and 0.5Ohm Resistance. Now say that the resistance of a glow plug dropped to 0.4 ohms, then at 12v, you would have a 30Amp flow, or at 14.4v you would have a 36Amp flow. Thus, you are tending to exceed the relay contact specifications and premature failure without blowing a fuse. In the end, you could destroy the relay contacts, yet when you went to measure the glow plugs, you would see a resistance, so assume nothing was wrong.

Hope this clarifies my earlier posting and if any member out their (ie. Television) who has more experience of mercedes fault detection, please correct or concur my assumption.

 

[MJH03]

Hello, more about glow-plugs...

I have a '95 E250 Diesel & the glow-plug light has stopped coming on altogether when I switch the ignition on. But, as per the postings above, it comes on for 30-50 seconds once I'm rolling. The engine runs a bit rough at first (so obviosly the plugs aren't heating as they should at switch-on). I think this is likely to be the same problem, or can anyone tell me otherwise?

 

[mercury]

Sounds familiar-just had mine done (1997 E300turbodiesel).All 6 replaced by diesel specialist as I was afraid of snapping 1 or more! 3 had failed so it pays to replace all at one go.

 

[pan.rider]

thanks for your link about glo plugs i renewed all 4 glo plugs on my sprinter but the light on the dash still does not come on the van starts ok then after the engine has ran for about 2p3 minutes the glo plug light comes on then goes out after about a minute do you think i will have to replace the relay any idea,s where it is located any help would be greatly apprciated

 

[D3Less]

OOps
Think my C270 may have this problem, has a pretty good warranty on it from the independant dealer so hopefully should be covered.
Half fancy doing it myself but knowing my luck at least one will snap

 

[battwell]

reply for pan rider. glow plug relay sprinter.

it is located under the battery by 2 10mm nuts. it is easy to take apart. inside are fusible links which i have successfully re bridged with solder.
if changing glow plugs dont be fooled if they start to undo easily then go tight. thats carbon on the thread and they are a b-----r to get out. on a sprinter they are a pig to get at to drill if you snap one so dont!!! i had to remove the head on a 313 to repair a damaged thread for a heavy handed mate.