As the title states, my 54 plate D3 has developed a diesel leak from the FBH exhaust in the wheel arch. I have pulled fuse 28 to hopefully stop any more diesel appearing on my drive/elsewhere. I suspect the heater needs a service (it’s not been serviced ever afaik), it was still burning diesel, but I suspect it’s not a clean burn hence the leak. Does that sound likely/plausible?
I’ve started the removal process tonight and have the seal kit and 20mm bypass pipe ready, though I may yet get my local Indy to complete the removal as I just watched the video on the subject and saw how much coolant will end up on my drive. Don’t want to poison any local wildlife...Smoked swooshy side repeaters
LEDs
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LRP Tailgate release
RedTiger Dash Cam
9th Apr 2021 7:57 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5053
Fuel from the exhaust sounds like it has been overprimed! Has your burner been running very recently? I ask as a long run cycle usually burns off any residuals in the exhaust and burner.
Diesel is only pumped when the burner starts!yµ (idµ - eAµ) ψ=mψ
9th Apr 2021 9:41 pm
jamesj74
Member Since: 28 Jun 2013
Location: Derbyshire
Posts: 89
Yes, on cold mornings it’s been smoking away as normal.Smoked swooshy side repeaters
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Sill protectors
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9th Apr 2021 10:40 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5053
You can download the free webasto diagnostics online, then with the adapter and lesds from the site shop run the heater for 20 mins until it burns off the crud and any residual fuel.
If you're still seeing a fuel drip it's not from the heater.yµ (idµ - eAµ) ψ=mψ
9th Apr 2021 11:36 pm
jamesj74
Member Since: 28 Jun 2013
Location: Derbyshire
Posts: 89
It’s 100% coming from the heater exhaust. I have seen it dripping from the exhaust pipe with my mk1 human eyeball. There’s no sign of diesel in the engine bay. Since I pulled fuse 28 it’s stopped dripping.Smoked swooshy side repeaters
LEDs
Sill protectors
Tinted lights
GAP IID BT 3
LRP Tailgate release
RedTiger Dash Cam
10th Apr 2021 1:54 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5053
The thing is there is no diesel in the burner unless its actually running, or you are priming it with diagnostics!
The introduction of fuel is the last operation of the start up sequence, and if there's any fault detected in the heater this final step is prevented.
It's possible the fuel feed pipe is ruptured and spilling onto the exhaust downpipe, giving the impression it's leaking from within the exhaust?yµ (idµ - eAµ) ψ=mψ
10th Apr 2021 2:06 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8235
Mouse attack? check the rubber pipe that feeds the heater, may have gone hard and brittle with age, can be a source of fire It can when others can't,
It will when others won't,
It goes where others don't.
10th Apr 2021 5:04 am
jamesj74
Member Since: 28 Jun 2013
Location: Derbyshire
Posts: 89
That pipe is fine. No damage or leaks there.Smoked swooshy side repeaters
LEDs
Sill protectors
Tinted lights
GAP IID BT 3
LRP Tailgate release
RedTiger Dash Cam
10th Apr 2021 9:22 am
jamesj74
Member Since: 28 Jun 2013
Location: Derbyshire
Posts: 89
Similar setting, sounds the same. Inefficient burn, white smoke, unburnt fuel, exhaust pipe becomes a fuel condenser, diesel on drive.
Member Since: 21 Oct 2016
Location: kent
Posts: 14148
Hi
Don’t know if it’s any use to u, but a few years back I noticed some fuel dripping off the FBH exhaust and after removing the wheel arch liner I found a fuel pipe connector tucked away that was leaking
See that it tracked down the chassis rail and down the FBH exhaust
Also clutching at straws but just an idea if u can test the fuel quantity flow rate to ensure the fuel pump is pulsing correctly and not letting by / faulty
Of course the other members here are a lot more experienced than myself , it was just that leaking connector and u saying it dripping off the exhaust sounded very similar so wished to at least share just in case u wasn’t aware of that hidden connector
Ps, drew a yellow line on the pic of how the fuels route that it took
Last edited by gstuart on 10th Apr 2021 2:19 pm. Edited 1 time in total
10th Apr 2021 1:56 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14148
PROFSR G wrote:
The thing is there is no diesel in the burner unless its actually running, or you are priming it with diagnostics!
The introduction of fuel is the last operation of the start up sequence, and if there's any fault detected in the heater this final step is prevented.
It's possible the fuel feed pipe is ruptured and spilling onto the exhaust downpipe, giving the impression it's leaking from within the exhaust?
Hi mate
Hope ur good
Me as always being a pain, lol, can I pick ur wise brain plse
Could a faulty dosing pump cause this at all please, ie if it’s letting by / faulty , therefore as it pulses isn’t shutting down correctly so allows more fuel in that it should so overfills and exits the exhaust
Will that software allow u to see what the flow rate is plse
Know I found on mine a leaking FBH fuel pipe connector that had tracked down the chassis rail and onto the exhaust , didn’t even know it was there as tucked away , only noticed it when I was replacing my front struts
As always apologises for the daft question, Plse forgive me
Stay safe
10th Apr 2021 2:01 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
It might appear to be running and trying hence the smoke, but it was most likely not running properly if at all, if it was actually running/burning there would no dripping diesel.
Mine does not smoke, every now and then you might get a whiff but thats it.
I have had this same failure recently on a boat webasto heater, and it was the flame sensor dud, 75 bloody quid plus gaskets = chuck it in the bin and fit a new chinese one.
On some diesel burning heaters the flame sensor and the glow plug are one and the same thing.
10th Apr 2021 2:14 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5053
gstuart wrote:
Hi mate
Hope ur good
Me as always being a pain, lol, can I pick ur wise brain plse
Could a faulty dosing pump cause this at all please, ie if it’s letting by / faulty , therefore as it pulses isn’t shutting down correctly so allows more fuel in that it should so overfills and exits the exhaust
Will that software allow u to see what the flow rate is plse
Know I found on mine a leaking FBH fuel pipe connector that had tracked down the chassis rail and onto the exhaust , didn’t even know it was there as tucked away , only noticed it when I was replacing my front struts
As always apologises for the daft question, Plse forgive me
Stay safe
Hi Gary.
All good here thanks, hope you are too!
The short answer to your question is no. If there is any issue with the dosing pump this would be picked up by the unit during the pre start-up test sequence.
I would agree with what lynalldiscovery says, as there should be no smoking from a regularly used burner provided is is allowed to reach full temperature before shutdown i.e. Avoid short journeys, or keep it lit until full temp is reached. yµ (idµ - eAµ) ψ=mψ
10th Apr 2021 3:45 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14148
lynalldiscovery wrote:
It might appear to be running and trying hence the smoke, but it was most likely not running properly if at all, if it was actually running/burning there would no dripping diesel.
Mine does not smoke, every now and then you might get a whiff but thats it.
I have had this same failure recently on a boat webasto heater, and it was the flame sensor dud, 75 bloody quid plus gaskets = chuck it in the bin and fit a new chinese one.
On some diesel burning heaters the flame sensor and the glow plug are one and the same thing.
Ah i see , many thanks, same here with mine where it doesn’t smoke and indeed also get the very occasional smell if I’m sitting at traffic lights
Ouch red the cost of the sensor
10th Apr 2021 3:51 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14148
PROFSR G wrote:
gstuart wrote:
Hi mate
Hope ur good
Me as always being a pain, lol, can I pick ur wise brain plse
Could a faulty dosing pump cause this at all please, ie if it’s letting by / faulty , therefore as it pulses isn’t shutting down correctly so allows more fuel in that it should so overfills and exits the exhaust
Will that software allow u to see what the flow rate is plse
Know I found on mine a leaking FBH fuel pipe connector that had tracked down the chassis rail and onto the exhaust , didn’t even know it was there as tucked away , only noticed it when I was replacing my front struts
As always apologises for the daft question, Plse forgive me
Stay safe
Hi Gary.
All good here thanks, hope you are too!
The short answer to your question is no. If there is any issue with the dosing pump this would be picked up by the unit during the pre start-up test sequence.
I would agree with what lynalldiscovery says, as there should be no smoking from a regularly used burner provided is is allowed to reach full temperature before shutdown i.e. Avoid short journeys, or keep it lit until full temp is reached.
Hi den
Good to hear ur ok mate , have been trying to put bits away in that new tool cabinet i got
Thank u and makes sense when u explain it like that
With mine , odd occasion of smoke on first start but that’s it , oh and occasional smell when sitting at lights but hardly know it’s on
Also remember to keep the fuel tank above the low level light as I didn’t realise at first when that light appears it also knocks off the FBH
Many Thanks as aways for the fantastic explanations
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check the rubber pipe that feeds the heater, may have gone hard and brittle with age, can be a source of fire 
