C8 2.2 hdi smokes after turning off engine

[Nickyjg]

Hi all hoping someone can enlighten me please.
I have a citroen c8 2.2hdi which always loves having problems. For a few months whenever I turn the engine off, after a few minutes it starts to plume out white diesel smelling smoke from under the middle part of the car (could even be the rear part of the engine) and mostly comes out the passenger side? Today I heard a vibrating knock twice before it happened? Runs fine had all new dpf filter, fuel tank and pipes/sensors and cambelt/water pump in 2015. Clutch Dec 2017 and flywheel April 2027. It is now in the mid 160k but need it to last as I need 8 seaters which are few and far between. Any heads up on what it is likely to be, cost etc...
TIA x

[RichardW]

Welcome along!

You'll need to get down to try and see where it is coming from. It could be diesel dripping onto something hot and vaporising. Is it a high spec one? It may have an auxiliary heater which is malfunctioning.

[Nickyjg]

I am not sure about high spec will look again later. It is in constant use. Aux heater? What would that be for?

[Nickyjg]

just googled the heater. Not sure. I know I get frustrated every morning for it to defrost... takes about 15 mins. Always has done really and much prefer the windows with heating elements in. As to heat internally. I think it is sufficient? I know my exhaust rattles at the back but certainly isn’t coming from there and thinking about it, a few weeks ago at some traffic lights it did it at idle and other cars gave me a wide berth. Not sure if that helps?

[myglaren]

If you post your VIN then someone will look and see what equipment and specifications apply to your car.

[wheeler]

Im pretty sure all UK spec diesel C8's are fitted with the aux Webasto heater.
It's normal for them to operate in colder weather & can run on for a few minutes after the engine is switched off to 'wind down'.
They are located under the car on the C8.
Have a look where the fumes are coming from, the unit was a little miniature exhaust pipe/silencer on it.
Sounds to me like it may well be normal operation.
They are fitted on a lot of larger cars now to heat the coolant up faster to give internal heat quicker.

[Nickyjg]

Hi. I still have not managed to get down to see but the engine is ticking loudly. Did this last year when my pulley split causing hard steering and so needed recovery... can’t see how it can be that again? Can it be accessed easily for someone to tamper with? Then again the alarm would probably go off?

[Nickyjg]

The smoke comes from a bit near the middle right hand side. Also when car is in idle at times, say at traffic lights. It is juddery too and the clicking noise, well, the disel ticking is much more prominent. Don’t want to put it through an MOT if all this is going on. Shall have to try and find another 8 seater

[wheeler]

Probably best to take a picture of where its coming from for confirmation.

[Nickyjg]

My son (only 12 but youtubes EVERYTHING cars!) reckons from the ticking and the smoke it could be the piston return springs? Does tick loudly too? Is that an expensive job?

[RichardW]

WTF is a 'Piston return spring'?? Don't believe everything you see on youtube....! Can you post a video of the car making the smoke and the noise, and perhaps get some pics underneath when it is smoking to pinpoint where it is coming from?

[Nickyjg]

Lol they are 4 huge springs in the cylinders which had collapsed causing the head gasket the split one end which caused coolant to mix with oil, this caused the clicking sound and white smoke. Once he put in new springs/coils and new head gasket, drained the oil and coolant and renewed it, the smoke and noise ceased

[Nickyjg]

I can’t do the video smoking from underneath as it is intermittent only the smoke from the exhaust at times which also gives off a strong diesel smell in the cab of the car

[Nickyjg]

And I somehow can’t post videos on here? As I have one of the engine noise?

[Stickyfinger]

WTF is a 'Piston return spring'?? Don't believe everything you see on youtube....! Can you post a video of the car making the smoke and the noise, and perhaps get some pics underneath when it is smoking to pinpoint where it is coming from?

Piston Return Springs, how to fix.