The 2.7 CRD was taking longer to start during the recent cold spell and coughing a bit of black smoke once started. Nothing too serious, about 3 or 4 seconds on the starter against about a second when warm.
Classic glow plug problem, I checked each plug expecting to find some of them failed, 4 of them were open circuit (burnt out in non electrical language) another was 124 ohm - as good as burnt out, it should be 1 ohm.
As Eurocrapparts were doing 25% off plugs I bought a set of 5 Beru OE plugs and as they were brittle, new plastic connector caps (£1.30 each from Mercedes dealer).
Not the easiest of jobs, you have to remove the high pressure fuel rail assembly to get to them and in true Sod's law fashion plugs 4 and 5, under the scuttle, were carboned up internally and put up a fight. Anyway all back together, fuel lines purged and engine started in about 2 hours total.
For 2 mornings now I have found not a jot of difference in the cold starting. I have checked that the plugs are working and I have even run a test LED direct from the relay so I can see when the plugs are powered, (the start delay lamp on the dash is pretty much meaningless as it doesn't actually tell you when the plugs are powered up).
Parts come to £60 my labour was free on that day. My recommendation is, if you're thinking of changing your glow plugs then think again, you're better off taking your £60 down the pub.
.....and if they haven't got Ruddles County then mine's a bottle of Bulmers please.
