Xantia 1.9TD splutters into life

[Old-Guy]

The Green Lady has suddenly developed a bad misfire when starting from cold. When stone cold she needs quite a bit of cranking to get enough cylinders firing to get the engine to run. After a bit of coughing and spluttering, and sometimes a second or even third attempt, she will run with a bit of throttle to keep the revs up around 1200. Pretty anti-social blowing clouds of unburnt diesel out of the tailpipe.

My immediate suspicion was a tiny air-leak, but it's not that as a good priming with the bulb immediately before starting makes not the slightest difference.

Compression appears to be good and not noticeably uneven across all 4 cylinders.

Once started and and the temperature needle off the stop, she starts first time as she's always done until now apart from a spell several winters ago of with dying battery in artic conditions.

The glow plugs are probably the originals (she's now done 117,000 in 18 years) so a couple of duff ones seem the most likely cause but I haven't even had time to check that the cable hasn't come loose. Fortunately I have a complete, almost new, set of plugs from the scrapped VSX. I'll have to make time on Wednesday afternoon to change them as we really, really need her early Friday morning.

When refitting the head last time, I deliberately left the plugs out until I'd primed and pressurised the lubricating system so I've got the essential spanner and know-how.

Any other likely causes, suggestions or thoughts please?

[CitroJim]

Glow plugs are always the first suspect in such cases Guy but as a further diagnostic test can you report on any smoke emitted from the exhaust during the hard starting attempts and initial spluttering?

None means no fuel, white means plenty of fuel but not being burned so if that's the case glowplugs or a lack of compression will be a cause and grey-black smoke means partial combustion which means poor compression.

Check your valve clearances if new glows and everything else doesn't fix it. The XUD has a quirk of having the tightest clearances when stone cold and if they have got too tight some valves can just hold open when the engine is stone-cold although right now it's not really cold enough to really show the problem up unless it's very bad.

[Old-Guy]

Thanks for the advice, Jim.

She blows a cloud of unburnt (grey) diesel vapour which is pretty anti-social! Other things prevented me having a look this afternoon. I wondered about valve clearances; once the temp gauge needle is off the stop and provided I wait for the glow-plug warning light to go out, she fires up 'instantly'.

[CitroJim]

That certainly suggests glowplugs Guy...

It's also worth checking they're remaining on when the engine initially starts and is idling - the post heat function.

They should stay on until the temperature is up to 60 degrees and/or the throttle is opened beyond 1/3rd...

[Old-Guy]

Recent events lead me to think it's not (only) the glowplugs, which I haven't yet been able to change.

Sunday was cold and foggy here. We had to go to a funeral on Monday morning (60 miles each way), so as I forgot to refill the tank on Friday, I went to do it late Sunday afternoon. I've got into the habit of priming the fuel system for the first start of the day, but didn't on this occassion and it took an awful lot of cranking before she spluttered into life blowing a lot of diesel vapour. Fortunately it's a 4-mile round trip to fill up so putting some juice bac

Monday morning, to maximise the chances of her starting, I primed the fuel system very thoroughly. Started with only the barest hesitation. Same thing early this morning.

Once she's been started in the morning, she's alright for the rest of the day though I've not had an opportunity to do a 'commuter test' of leaving her all day and seeing if she's then a bit reluctant.

Tomorrow morning, if it's not raining, I'll have a couple of hours spare to check the usual culprits: leak-off pipes (only a couple of years old) and fuel filter cover. Apart from the pipe from the tank to priming bulb, the pipe from bulb to filter is about the only part of the LP fuel system that hasn't been replaced in the last 3 or 4 years. I would have replaced it when I had the head off last April, but it has a tight "U" bend at the filter end and the Citroen part is NFP.

Does anyone know for certain what the ID of this pipe is please? citroen.service states 8 x 10 but I've learnt not to trust the dimensions or the shapes shown.

Also any suggestions please for a source of transparent diesel-proof fuel pipe in various diameters?