hunting at idle when started from cold

[SilverSaloon]

on my W124 E300 Diesel (1994) when started from cold the engine "hunts" for 20 seconds or so. it never used to.

any ideas what this could be?

after idling for 20 seconds or so, or rev'ing it, it then idles fine.

this is on normal diesel so its not the veg.

i still do have some minor fuel leakage but nothing major now - could this still be the cause? the fuse in the OVP is fine.

cheers

derek

 

[Number_Cruncher]

>minor fuel leakage but nothing major now - could this still be the cause?

Yes, very easily! On mine, I remember it starting, running OK for a second or two, and then beginning to hunt. I could see the air moving around in the pipes.

Top candidates are; the leak off pipes from the injectors, and the fuel pre-filter o ring.

Even when everythings right, you'll still get a small bubble in the left hand pipe just as it goes into the fuel filter block, but that's fairly normal.

 

[SilverSaloon]

>minor fuel leakage but nothing major now - could this still be the cause?

Yes, very easily! On mine, I remember it starting, running OK for a second or two, and then beginning to hunt. I could see the air moving around in the pipes.

Top candidates are; the leak off pipes from the injectors, and the fuel pre-filter o ring.

Even when everythings right, you'll still get a small bubble in the left hand pipe just as it goes into the fuel filter block, but that's fairly normal.

i know there are still leaks - but as per my other fuel leak thread i still need to change some of the o-rings.

got one more to change that is relatively easy to get to - the rest may either involve getting under the car or removing the manifold.... both something i wont be able to do for a while, but atleast the main leak is gone and the car starts easily now.

i guess until i've changed ALL the o-rings i shouldnt suspect anything else

 

[Number_Cruncher]

>> i guess until i've changed ALL the o-rings i shouldnt suspect anything else

Yes, I think that's fair comment. I remember that the leak off pipes from the injectors were really quite brittle, and didn't make a good seal at all.

You can get the cross over pipe off without too much work - if you remove the sheet metal braket that supports the cross over tube, and then slacken the bolts which hold the EGR valve, there's enough room to wiggle the pipe out without disturbing anything else.

 

[Dieselman]

Is it still coughing on start, if so suspect a glow-plug going down.

 

[SilverSaloon]

Is it still coughing on start, if so suspect a glow-plug going down.

its fine when the car is warm. it only happens when v cold for 20 secs or so.

the car has new glowplugs on (well about 3000 miles old now) and were fine until recently.