Glow Plug Light On and Flashing

Discussion in 'Engine' started by mbenz76, Dec 23, 2014.

  1. mbenz76

    mbenz76 Hardcore MB Enthusiast

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    Today after work I started the car and after a couple of minutes driving noticed the glow plug light was on. Now I am usually good as waiting before starting up so I assume it went iff and came back on but I could have started before it went off.

    After about 5 mins of driving the light went off and I didn't see it on again all the way home (20 mins).

    When I got home I turned engine off and fired back up to check (engine at full temperature by now) and it started fine and light didn't stay on. But then I noticed it flash - very briefly. Then again. So I sat watching with engine ticking over and it flashed about every 20 seconds or so.

    I have booked in to get car looked at and they assume glow plug failure, but has anyone else any advice on what it could be if not that please? Also with MB wanting over £200 for a set of 6 if it is the plugs, what is my best bet online for genuine parts cheap as they will price match if I get a verifiable alternative.

    For info the car has done 49k miles in just under 5 years and I have owned from new and treated it well!

    Thanks
     
  2. OP
    OP
    mbenz76

    mbenz76 Hardcore MB Enthusiast

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    Just been out in car again and noticed that the glow plug light came on as usual and then went off as usual so I started the engine as I normally would, the glow plug light then came back on and stayed on for about one minute before going out. Engine was 50% normal temp at the time I started it this time.

    As I drove I noticed the glow plug light does flash every 10 seconds. By the time I got where I was going the engine was at temperature and the light had stopped flashing and gone off completely.

    If this is glow plugs, is the only consequence of failure a difficulty starting in the cold or are there more serious consequences?
     
  3. BIG_G_1979

    BIG_G_1979 Hardcore MB Enthusiast

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    Yep one or more glow plugs have failed same happened to mine a few weeks ago I changed all 6 plugs and problem is solved, ecp have a sale on at moment I was able to buy 6 beru plugs (oem plugs) for 65 quid
     
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  4. OP
    OP
    mbenz76

    mbenz76 Hardcore MB Enthusiast

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    Thanks for the reply. At least it is nothing serious. Didn't know if the warning light was shared by other faults.

    Is 49k a good life for them or am I seeing a premature failure? Never owned diesel before so not sure.

    MB reccomend changing all 6 but is that right? Can I get away with just changing the faulty one?

    Just looked on Eurocarparts and they only list NGK for my car, on sale at £27 each. Which is very close to what MB were asking with labour all in so could be tempted to go with MB direct.
     
    Last edited: Dec 23, 2014
  5. BIG_G_1979

    BIG_G_1979 Hardcore MB Enthusiast

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    Im using the app so cant see ur model, my had 73k on clock, u could just change the faulty one but in my opinion the rest could be on thier last legs too? Thats the gamble for piece of mine I would just change all 6.
    Hard to say if its premature failure I also have a mg zt diesel and its still on its original plugs and its 04 with 142k on clock I think its just luck of the draw but like u say its not serious just cosumable items
     
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  6. OP
    OP
    mbenz76

    mbenz76 Hardcore MB Enthusiast

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    I got in the car with slight trepidation this morning wonderingg whether I would have an issue with the glow plug or not.

    Eveything normal!

    No glow plug light after turning over and no flashing. Stopped and started engine 3 times so far this morning and no issues at all.

    Could it be a glitch or a sign of failure due and is it worth me doing anything at this stage if the lights is back to normal?
     
  7. sallison1504

    sallison1504 Hardcore MB Enthusiast

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    Could be a bad Glow Plug Control Unit relay thing.
     
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  8. OP
    OP
    mbenz76

    mbenz76 Hardcore MB Enthusiast

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    If it doesn't do it again over Christmas then I think I will cancel garage visit and just see how it goes.

    Never had a problem until yesterday and engine turns over first time everytime regardless of temperature.

    I am working on the assumption that if one plug fails, the engine will still start as 5 other cylinders will work and the 6th will get compression from the other 5 turning and so work. Or is my logic wrong?
     
  9. sallison1504

    sallison1504 Hardcore MB Enthusiast

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    Glow plugs aren't really necessary in UK climates. Without them could be a problem only in the most extreme conditions, like less than 0 degrees, otherwise the light only usually comes on to say it's working like most of the other lights. Compression is only obtained by the motion of the engine and piston etc, the glow plug aids the initial combustion of the diesel as its harder to ignite at lower temperatures. In other climates where starting everyday at less than -10, they are needed, where over here, they just help reduce wear on the engine on the occasional cold start.
     
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  10. OP
    OP
    mbenz76

    mbenz76 Hardcore MB Enthusiast

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    Just wanted to update the thead

    Can has been in to MB this morning and it has been diagnosed as the glow plug relay.

    All being done under the Tier 1 warranty I have.

    Thanks for all the help.
     
    1 person likes this.
  11. sallison1504

    sallison1504 Hardcore MB Enthusiast

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    You're very welcome. Glad it was all sorted.
     
  12. Cell

    Cell Member

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    E350 Estate Sport
    Thanks for this info. My E350 Sport Estate started doing this yesterday, looks like a visit to MB today.

    Did you also change the glow plugs or just relay?
     

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