w124 e250d cold start issues.

[djp]

hi, i'm new here and to mercs and diesels in general. bought a e250d three months ago and recently it's developed a cold start issue and by the looks of it has also killed a set of glow plugs in the process.

when trying to start the glow plug light doesn't light up when it's meant to and it takes a bit of cranking on the starter motor and pumping of the accelerator to get it going, once it kicks into life there's a large amount of smoke from the exhaust. although i've got these issues, once it's turning over and it's warmed up it drives fine and the glow plug light will come on for a bit once i start driving.

i've been googling this issue and i've been reading about adjusting the valves and was wondering whether this would solve the problem, along with replacing the glow plugs, of course!

if anyone could shed any light on this i'd be grateful! (it's booked in to go to the garage tomorrow, but if i can tell them anything to speed up the process that'd be ace!)

 

[Blobcat]

Hi & Welcome,

On my previous E if the glow plug light came back on after the car had started it denoted that one or more of the glow plugs is faulty. From reading your findings it sounds like yours are faulty.

 

[djp]

would that be the sole cause of the cold start issue? the glow plugs had failed on the vehicle when i bought it and in comparison, the cold starts are not as bad then as they are now, although that may be due to the change in the weather!

(edit)

i forgot to mention that i had the glowplugs replaced when i bought the vehicle three months ago and they've failed again, so i'm a little worried as to why they've failed again so quickly.

 

[maxypriest]

Sorry to hijack this….

I was going to write about my G- Plug light that sometimes comes on after the engine has started. Incidentally – it starts perfectly, even when that happens.

Is it defiantly time to change the plugs? They were don 30-40k ago…

How can I check?

Regards,

Max

W124 E300D 24V

 

[Blobcat]

DC resistance check of the individual plugs will show the faulty one(s)

 

[wireman]

The engine will have great difficulty in starting without the prestart glow, in summer it might just go but in winter you would be wasting your time and wearing out bits that should last the life of the car.

The huge quantity of black smoke on starting is the excess fuel which has been pumped into the engine being burnt or evaporated in the exhaust system, not to much of a problem but it will choke any devices fitted into the exhast system to green up the emmisions and eventualy reduce the fuel efficiency of the engine.
Additionaly the fuel wetted cylinder walls and piston rings will be under lubricated for a short time after the engine is started just when its needed most, in short the engine will be damaged and its life shortened if the starting is not improved.

There are several posts dotted about on this forum regarding the preheat systems on various models some have greater details than others but most of what you need is in them.

Your fault could be in the plugs, the relay unit (or its internal fuses), the big fat wire to the relay from the battery or the wires/connector from the relay to each glowplug.

Expect the resistance of each plug to be in the region of 0.7 to 1.1 ohms, hard to measure with most test meters but continuity should be a reasonable indication of servicability. Mind you dont snap of any plugs if/when you try to remove them.

Please tell us what you find and so enable others to be assisted.

 

[djp]

hey gang, turns out my glow plug relay was borked, it was staying on for a long time after starting and had thus successfully burnt out 4 of the 5 glow plugs. i had the plugs and relay replaced and starts first time now, although when cold i still get a little shake as it settles to idle. fuel consumption also seems to be improving with this as well, although that's most probably just a coincidence.

hope this helps.

 

[wireman]

The little shake might be caused by tired out engine mounts.