Diesel Cold Starting (No Not Glo Plugs!!)

[steve kane]

No not another Glow Plug Tale! but we have a 5 cylinder C250D (non Turbo) which is a good runner, it used to start without any difficulty and go onto an even tickover, now we find that although it still starts just fine the cold tickover is extremely lumpy and it is not until we have revved it a few times that it begins to sound happy, once warm of course everything is just fine. I'm wondering; what are the mechanics of the cold starting, is there a fast idle device/program, is it to do with the "regular suspect" Mr Maff??
any ideas?
Steve.

 

[Hibbo]

This could still be a glowplug issue! The light may come on and go off normally, but you may still have lost one.

The only 'cold start' mechanism is afterglow (the plugs staying on after the engine has started). A dodgy line from temp sensor to glowplug relay could cause this, or the relay itself.

I'd get the multimeter out, check the resistance to earth of each glowplug (just do it from the plug) and then check the plugs are remaining one after a cold start.

These engines are also very susceptible the air getting into the fuel lines, it may take a good rev to bleed it out. Watch the translucent lines as someone starts it and look for bubbles.