Engine misfire on C250 TD when cold

[KLP 92]

I have devoloped a problem on my C250 diesel. On cold starts the car has a slight mis, noticable when free revving in neutral at approx 1200 revs. Only happens for the first few minutes when its cold.

It may be related to changing the glowplugs. One snapped in the head, so with great difficulty it was removed in situe, but the injector pipes were taken off.

I have used injector cleaner but no joy. The mis dissappears after a min of 2, and does come back during the day.

The other thing i've noticed, which may be related is that the engine is more noiser, a bit more clatter on start up than normal. It dissapears after 10-20 seconds, but nevertheless there.

Am i looking at a blocked injector?

 

[Parrot of Doom]

Exactly the same issue on mine, I know for a fact that its the EGR valve. Goes away once warm.

Do a search for EGR, you'll find plenty of info Once I'd cleaned mine, it got a lot better but still not perfect.

As for the noisey startup, lots of engines do that, especially when the oil is getting on a bit. What oil is in yours, and when was it last changed?

 

[KLP 92]

My EGR valve has been disconnected/blocked for the last 8-10 months, so i don't think its that.

The oil has just been changed, by the guys that removed the brokem glow plug. I shall be replacing the oil again, using a higher grade of oil, a bit thicker as well. I think it has 5-40 semi synthetic at the moment, a random brand. I normally use 15w40.

The car has no loss of power/lumpy idle etc after the first minute after a cold start.

Can it be something do do with the glowplugs? The warning light doesn't come on though and it does start, just takes an engine turn more.

I'm off to the States tomorrow so will resolve this when i'm back.

 

[KLP 92]

I stripped the EGR valve down a few months back, cleaned it but never bothered connecting it back up.

 

[Dieselman]

It sounds like a glowplug issue. You need to checkall are working.
After that it could be a squiffey injector so you could have them tested.

None of the injector lines are leaking are they?

If you crack free each line in turn you should find which cylinder is making the noise.