White Fuel mist drifting from under the bonnet/left side front wheel

So I stopped and switched off !
Hi All
I have my Discovery III TDV6 S 2006 in Europe and she's been fabulous as a tour vehicle, until I had a reconditioned gearbox fitted by a Greek garage just a couple of days ago.
200 miles after picking it up after the gearbox work, she's running very well, no loss of power, smooth idle and running; but suddenly when pulled up but with engine running we had a plume of white mist, smelling strongly of fuel and looking like fuel vapour drifting out of the gap between fuse box and LHS of the engine (LHS looking forward).
There was too many obstructions to see where the vapour was coming from while I was at the side of the road. I'll start dismantling the wiring loom, etc that obstructs the view after I've checked with you good people to see if I'm facing anything obvious. I suspect a leak from the high pressure rail or an injector, but I'm surprised by the fine mist, rather than a spurt of more liquid fuel. Also, the car is running well??
I've searched the forum for any similar posts, but drew a reletive blank, so maybe not a common problem (or my search capability is uncommonly rubbish).
Any initial ideas on what I'm facing. Any pointers to previous posts that I should look at?
I can't drive as the mist is likely to be very flammable, so any thoughts would be very welcome.
Best
Paul

Was it below 5°C? If so, it's going to be the Fuel Burning Heater exhaust, possibly due to the not firing correctly.

FBH fuel pipe leak, not unknown and can set your car on fire, if you look at the front of the fbh you will see a small 90 degree rubber hose, this gets hot and splits.
Google to find whcih is the CAN plug on the FBH, pull said plug and carry on with your tour and sort it out when home.

Any problems with fuel burning heater would certainly sound a whole lot cheaper to fix than maybe a leak from an injector or high-pressure rail which I thought I may be facing! Its just that the cloud of fuel vapour was coming from the gap between the fuse box and engine when the hood was up. There was so much of it that its probably overflowing into the wheel arch. The FB heater is forward of the fuse box, and looks like its nicely and tightly fitted. Its also between 14Co-25Co here in Greece.

Now that the engine's cooled I can get my hand down the side of the engine. With the engine running, I can feel dripping fuel onto the LHS exhaust manifold.

Well all thats down there that is fuel related is, injectors/injector pipes/leak of pipes and the common rail, not sure which end the hpfp feeds the common rail?
The mist would suggest it is high pressure fuel, so possibly cracked/loose injector pipe (17mm spanner) or maybe the injector sealing washer is leaking, normally easy to tell as they leave one hell of a mess around the leaking injector.
The gbox guys may have inadvertently knocked one of the leak off pipe unions.

The rear most injector left hand side (uk car) is a right toss to get at!

Brilliant info Lynall, many thanks
From what I can see the top of the engine is fairly clean/dry, but below the line of the injectors it starts getting very oily/carbon black, and wet with fuel. The leak only seems to happen with the engine running, but then that would apply to high and low pressure lines. The reason I'm hoping its a low pressure pipe is that the engine runs smoothly and doesn't seem to lack power/response. Would it be more likely to be affected if the high pressure side is leaking - it just seems it might.
If it is the low pressure pipework, I'll probably need it up on a ramp to change anyway, given the lack of access to that area, unless someone is really familiar with the pipework around there and can take a guess at where the split/break might be.
I'll go run it and see if I can crawl under and look up at where the flow is coming from, but the exhaust manifold might get in the way . . .
Having never experimented with spraying diesel onto a hot manifold, I don't know whether it results in white misty fuel vapour. Does anyone here know or have had this experience?
Thanks to all for your help and interest
P

Objective said:

Brilliant info Lynall, many thanks
From what I can see the top of the engine is fairly clean/dry, but below the line of the injectors it starts getting very oily/carbon black, and wet with fuel. The leak only seems to happen with the engine running, but then that would apply to high and low pressure lines. The reason I'm hoping its a low pressure pipe is that the engine runs smoothly and doesn't seem to lack power/response. Would it be more likely to be affected if the high pressure side is leaking - it just seems it might.
If it is the low pressure pipework, I'll probably need it up on a ramp to change anyway, given the lack of access to that area, unless someone is really familiar with the pipework around there and can take a guess at where the split/break might be.
I'll go run it and see if I can crawl under and look up at where the flow is coming from, but the exhaust manifold might get in the way . . .
Having never experimented with spraying diesel onto a hot manifold, I don't know whether it results in white misty fuel vapour. Does anyone here know or have had this experience?
Thanks to all for your help and interest
P

Click to expand...

Can you hear a slight chuffing when its running?
I changed all injectors on mine and a few weeks later could hear an odd noise, turned out drivers side middle injector (luckily easy to get at) was leaking past the copper washer, the copper washer and one of the cheap injector seat cutter kits off ebay (15 quid) and she has been good ever since.
Like I said above the passenger side rear injector is a right tawt to change, literally no room at all, all the other 5 doddle.
The black oily carbon mess could be the clue the injector seal is leaking?

Brake cleaner is excellent for cleaning off split diesel.

I am not even sure if there is any low pressure piperwork down the sides of the engine? the supply pipes and the low pressure test valve are on top

Might be worth adding a vid of the engine running, mainly so we can hear it?

I'll do a video and you might hear over-zealous "tappets", but otherwise a smooth running engine I think.
Thanks again to Lynall for the tip on getting the black gunge off my hands, I might show you all a video or pic of my nails, and since - I crawled under the vehicle - a photo of my blacked face just to show how useful that tip is. Worse thing is, although i got a whole load of diesel in may face, I couldn't see where it was coming from. Looks like a stream of fuel rather than a mist now that the manifold is cold though.
Thank you good people - you are legends.
Paul

Objective said:

I'll do a video and you might hear over-zealous "tappets", but otherwise a smooth running engine I think.
Thanks again to Lynall for the tip on getting the black gunge off my hands, I might show you all a video or pic of my nails, and since - I crawled under the vehicle - a photo of my blacked face just to show how useful that tip is. Worse thing is, although i got a whole load of diesel in may face, I couldn't see where it was coming from. Looks like a stream of fuel rather than a mist now that the manifold is cold though.
Thank you good people - you are legends.
Paul

Click to expand...

If you get a big screwdriver and use it as a stethoscope, you might find the tappety noise is the injectors rather than the tappets themselves, ie its normal.

O.K. Bright, sunny day and I think I've got it . . . or thereabouts!
In fact, I think I have two problems.
The first is the fuel.

I have a video of leaking fuel, with only some doubt as to where it is coming from. It <<looks>> like the end union of what looks to be the common high pressure fuel-rail for the injectors. There is a screw-on union that might have blown its seal.
The other option <might> be the inside injector that is spurting high pressure fuel over that same end union, making it look like the furl-rail union is at fault. (What a B...stard
Of course, that inside injector is a legendary inaccessible unit, but then is the rail any better?
I've got a pretty clear video of the tinkling fuel, which then drips down onto the exhaust manifold, which would account for the steaming fuel vapour I first saw.

How do you upload a video here? Should I link to one, and is that allowed for a Newbie?

My second problem :
Looks like a spark is discharging from the injector electrics (middle injector) onto the engine body.
Fuel mist and a spark - legendary !
As is clear in the photo, the heat of a stationary summer seems to have dried out all the insulation tape on the wiring loom. Most have just given up and started to unwind. I'm sure that I see a discharge leap around 15mm from one of these unwound connections onto the engine body. I'm surprised - I wouldn't have thought the voltage on these wires would be high enough.

I hope its just a case of rewinding new tape. Any opinions on this would be very gratefully received.

Test to see if I could load a video...failed!

OK, so eventually have cracked the problem. The fuel return pipes and connectors consist of 4 or 5 sections, connected by small black plastic push-fit connectors. One of the black connectors - I'll post a photo - has a small split in it, and so its section of pipe wont locate properly. New part required.
The whole assembly is a "part" and so it comes in at Eur350 to be sent from UK
What with Brexit delays outbound, delivery took nearly 8 weeks, followed by 20 mins to fit !

If anyone needs any further info on this problem, I'll happily provide.
Thanks to all that helped enormously with the suggestions and support. It makes a difference working through the problem with others. Best regards to all.