Project BX17RD - the further adventures of PBO

[vulgalour]

Had another look at this today to see if I could find anything amiss.  The car isn't keen on starting, or restarting, and the injection pump is now making a wubbawubba sort of a noise so I guess that means something in the pump is on its way out.  The wubbawubba gets quieter the longer the car is running, but it required two attempts to start with or without priming, as though the pump wasn't pulling fuel through quickly enough.  The wubbawubba noise is similar to the one that a mechanical fuel pump diaphragm makes, that sort of wobble board meets air sucked through a straw type of noise.  I couldn't capture it on my phone because the engine drowns out the rest of the noise.

No diesel leaking out anywhere and while I'd like to say there was no air getting in, since I don't have see-through fuel hoses I can't say that for certain.  Once running the car is fine and try as I might I can't get it to repeat the stalling issue.

So I guess at a minimum an injection pump rebuild is on the cards to try and resolve this issue.  My concern is that the badly filtered used veg oil remains I found in the bottom of the fuel filter housing has perhaps but excessive strain on the pump and simply worn it out, which would mean replacement is the only option.  I don't know though, I'm learning as I go here on this one and not entirely sure what the wisest course of action is from here.

[vulgalour]

Had a bit of a natter with some people, and we're going to try some injector cleaner first.  Theory being, with evidence of chip fat in the system I could have gunked up injectors and a bottle of cleaner is very cheap and could well solve the issue without me taking chunks of complicated things apart.

[Fabergé Greggs]

Could it also be the leak-off pipes letting in some air? 

[vulgalour]

Theoretically yes, though they look in excellent shape and aren't leaking diesel out, I'm pretty sure @dean36014 did them not long before I got the car off him.

[lesapandre]

Look at the fuel tank uptake if you can get to it on these. The filter gauze and uptake pipe can get full of gunge that grows in the tank on little used diesel vehicles. My Citroen was virtually completely blocked which led to fuel starvation.

The other thing I would replace, if not replaced recently is the fuel filter.

[dean36014]

Yes I replaced the leak off pipes with decent mercedes pipe I had in stock

[RobT]

Another possible culprit is the plastic fuel filter housing.  As others have documented online, the housing can crack causing air to leak in. If you've cleaned the housing out recently you may have inadvertently opened up a crack.  The fix* is to replace it with a BMW E46 320d fuel filter.  I tried this on my 406 that has a rough running/stalling issue when cold.  It's a 2.1 XUD. It didn't work unfortunately, but is something else to consider.

My next port of call is to replace what I think is one dodgy injector.  Hopefully yours could just do with a good clean out.

[Cleon-Fonte]

Has the fuel heater down the back of the engine been blanked off yet? It's a well documented air ingress point and bypassing it shouldn't make any difference.

 

[vulgalour]

Fuel filter is all metal on this one, and there's cracks or damage, it's not leaking  The fuel pre-heater hasn't been bypassed, it's still as Citroen intended.  I didn't want to poke that bit in case I found out it was something else like a blocked fuel filter or something so it's on the list, but not a priority.

[vulgalour]

Earlier today I was hunting out some stuff in the garage and found some H4 yellow headlight caps that I'd bought for my old Renault 6.  I had thought I'd moved these caps on, they didn't fit the headlight bulbs in the Renault, and I didn't have another car to fit them to, turns out I hoarded them instead.  They literally just clip on to a H4 bulb and that's it.

They have the added advantage of making it impossible to touch the bulb glass once fitted.  I had to wait until I'd finished work before I could see the result and while my camera overcompensates with blue, making the photos it takes look like an early Star Trek set, I've got photo editing software and I'm not afraid to correct the balance.  In person, the yellow it puts out looks just like it should, no a dirty old-bulb sort of colour, nor a harsh brilliant yellow, just this very mellow glow reminiscent of news footage of France in the 80s.

Time will tell if they're actually horrible to drive with at night and whether or not they actually keep their yellow colour.

 

[RobT]

Must admit, although the 11 looked rather sexual with yellow bulbs fitted, the night vision was shite so I've gone back to normal ones.

[vulgalour]

I'm hoping the BX isn't too bad as the night time light output without the caps is actually surprisingly good.

---

BX needed to be moved today since I was doing a spot of garden maintenance.  It started up with a bit of reluctance and after I'd parked it elsewhere I went back and found this big puddle of diesel under it.

That's a lot of diesel.  Before opening the bonnet I had a look underneath to see if I could find it and all I could really see was a lot of diesel had leaked from somewhere higher up in line with the injector pump.

Hmm... let's pop the bonnet and see what's what.  Ran over the various fuel connection points and saw that the top of the injector pump was greasy with diesel.  With the engine not running it wasn't readily apparent where it was coming from aside from a slight dampness on the outlet/return on top of the pump.

I had inspected these hoses recently and had seen nothing untoward.  Indeed yesterday they weren't causing any diesle to come out and the pump didn't have a greasy sheen of diesel on it like it does here.  Better start it up and see what's what.  Car was a bit reluctant to start up.  These shots were taken after I'd removed the hose clamp for the bigger non-braided hose when I'd had chance to clean my hands so I could use the camera.  With the car running it soon became very clear where the leak was.

A bit of throttle and it was REALLY clear.

That's a surprise, to be quite honest.  Easily rectified at least... but wait, what's that I see in the camera that I didn't see in person?  *tickatickaticka* Enhance.

*tickatickaticka* Enhance.

You have got to be kidding me!  Another failed hose, and another fairly new one at that.  I bet that's sucking air in and cocking things up isn't it?  I haven't got enough hose in stock to replace this with and the hose itself isn't long enough for me to trim the end off so I'll have to order a new length and replace the whole thing.  These cracks are not visible in person, I only saw them because of the camera showing them up.  The digital camera, the tool we all forget we've got when it comes to spanner time.

Oh well, I trimmed the leaking portion off the braided hose and refitted it.  I will be buying enough hose to replace all the leak-off pipes as a precaution when I buy the other hose to replace that big cracked one.  Maybe that will fix the issue.  When the braided hose was removed it was almost impossible to see the crack that was causing the leak, it's no wonder I couldn't find it until it properly failed.

Hooked it all back up and the car, unsurprisingly, started much more willingly than before and didn't leak any more diesel out.  Gave it some throttle and it was fine, no leaking out of diesel.  However, on pulling back onto the drive it did that trick of the idle dropping until it stalled.  It did fire up again quite willingly so it's slightly improved which ties in with the slight improvement I made by trimming down that bad hose so perhaps when I replace all the other fuel hoses it will be okay and this problem will go away.

I also learned quite by accident how the driver's side mudflap got broken at some point in the past and why you shouldn't park too close to the curb.

 

 

[dean36014]

Bloody hell that was genuine mercedes Benz leak off pipe. I remember buying for a Merc I had and it didn't get used and got used on the bx instead. Doesn't inspire confidence really in the quality of parts on the market at the moment. At least it was an easy fix.

[vulgalour]

Some days, you don't even get as far as suspension goes up.

[stuboy]

certainly keeps you busy the ol' bx

[vulgalour]

s'funny, when I was driving it up and down the country it gave me much less issue than it has while it's been sat more idle since moving house.

[paulplom]

It looks brilliant. 

Cars don't like being idle. They weren't designed for it.

[Tadhg Tiogar]

2 hours ago, paulplom said:

Cars don't like being idle. They weren't designed for it.

Citroën BX: Loves driving. Hates garages.

[vulgalour]

Right then.

Getting the old return fuel hose off wasn't too bad.  It helped having someone wiggle it at the engine bay end so I could see which hose it was underneath the car and then it was a case of wiggling it out of the metal clip on the inner wing and the two plastic clips that hold it to the other fuel hose.  It's just a push fit onto the metal pipes at each end, there's no additional clips.  The rubber hose had welded itself to the hard line under the car and had to be sliced off with a Stanley knife, it was otherwise fairly plain sailing.  Checked it against the length of hose I'd ordered and fortunately the hose I ordered was exactly the same length, so no cutting required.  That's also when I found this large crack in the old fuel hose that had been hidden by the metal clip on the inner wing.

Fitting the new hose wasn't too bad, the fit was a little looser than the old hose so I added a hose clip just to be certain it wouldn't leak or fall off, it does measure the same size as the hose I took off so the difference must be very tiny.

I then finegled the hose down through the rats nest of other stuff to get it under the car so I could connect it to the hard line.  It was easier to pop the hard line out of a couple of its clips to line the two halves up.  I then secured it at this end with a hose clip too, just in case.  It's worth noting that the interference fit on the hard line underneath the car was much better and a clamp probably wasn't needed.

I then moved on to the leak-off hoses.  The new hose measured the same as the end I'd disconnected from the pipe on top of the injector pump, and it turns out this is too big for the injectors, so now I have to order some smaller hose so that I can sort those out.  Interestingly, when I popped off the leak-off hose furthest away from the pump (passenger side), it was very dry, especially when compared to the others.  I don't know if this is normal, or if it hints at a problem with this injector.

I reconnected the hose and started the car up.  Whatever had been leaking diesel - and honestly, I couldn't find anything underneath the car or down the back of the engine that looked like it even had diesel going in or out of it anywhere remotely near where the diesel leak had been - now wasn't so perhaps it was some diesel trapped in a nook from the previous leak, or perhaps it was that return hose I've just replaced leaking in a way that wasn't obvious.  Either way, the car did start much better on restarts and while it did stall once on doing the three-point turn to come back on the drive, it was otherwise vastly improved.  If you give it a lot of throttle and then let it idle, it will do so without the wandering idle for much longer now, and is far less inclined to stall.  I hope that means replacing that one hose got rid of a large air leak, causing the improvements, and that the remaining issue can be solved by the injector cleaner I'm waiting on being delivered, and replacing all the leak-off hoses when the correct size I order arrives.

[vulgalour]

The new leak off hose arrived so I thought it'd be a quick job just to pop out and fit that and then the air leak issue will be solved, right?  RIGHT?  Let's pull off the old ones.

These didn't look particularly bad, a little stiff perhaps.  Fitting the new ones was nice and easy.

Once primed, and a fair bit of cranking, the car did fire up.  It restarted willingly too.  This was good.  I left it to idle for a bit and then the car just slowed down and stalled.  A restart was more difficult and when I primed the pump this time I could hear air squeaking from somewhere near the pump or the filter, just not quite where.  Car was an absolute pig to get to start again and wouldn't idle for very long so I knew I had an air leak somewhere and it must have been a pretty bad one.  Not sure where it would be exactly, I checked over all the connections I'd disturbed and noticed some chafe marks on the new hose going into the new fuel filter housing, so I repositioned those.

While this was good for routing the pipes, they squashed right up against the bonnet and the pipe going to the injector pump was a bit too close to the mechanism for my liking.  I readjusted everything again to fix that so now the pipes can't chafe or touch any moving parts.  The shorter hose has a bit of a kink so I will probably have to replace that with a slightly longer piece and then I'll cable tie the hoses together so they don't flap about.  I wish I could just get the proper kind of original filter top new, then I wouldn't have this routing issue.  I did try fitting them to the opposite side of the filter housing and the LHM reservoir gets in the way.

That done I tried to start the car and could see diesel bubbling, literally, out of the top of the fuel filter.  I reckoned I'd found my air leak and, annoyingly, it was where the new parts were.  Removing the fuel filter confirmed it.  The top O ring has stretched massively and I don't know why, I was very careful installing it and didn't pinch the seal.  I put the filter and top together off the car when I replaced them and then fitted it to the car, so nothing should have been unseated.  Suffice to say, I've ordered replacement seals, perhaps that will cure the air leak issue.  It is annoying when new parts fail, this filter and seals have done maybe four miles total.

[vulgalour]

I had bought a Volvo 240 high level brake light for the BX, something I was going to make brackets and whatnot for.  Then while shopping for something unrelated I had the sort of high level brake light I actually wanted to fit pop up in my suggestions.  The algorithm worked!  So today, I'm going to show you how I fitted this without a soldering iron and with the help of a C clamp.

The first task is the scary bit, I had to remove the inner C pillar trim to check the wiring route I wanted to take was viable.  There is wiring that runs into the tailgate for the central locking, so that gave me access from the tailgate into the car so that's the route I chose to take since it should be the most straightforward.  First job is to remove the two small screws holding the top of the C pillar trim in place and then gently prise each of the fir tree studs out of the holes to get the C pillar trim off.  I did not enjoy this part of the job one bit.  You also need to be aware there's a plastic hook on the point at the back of the car, you don't want to be snapping that off.

That done, it confirmed the wiring route I wanted to take could be taken quite easily, didn't even have to drop the headlining, just ease the very corner out so I could see when the wire had been fed through.  Before committing to anything, I then took a look at what the book suggested was the wiring diagram so I could determine which was the wire I need to splice into...

er... NOPE.  I couldn't figure out how any of this, or any of the other wiring diagrams, related to what I saw on the car so instead I chose the practical approach.  Built into the back of the light clusters is sort of a printed circuit board, only it's made out of a sheet of metal, that's held in place by melted bits of plastic.  Looking at this I could understand which sections of it powered the brake and running lights and that it correlated to the brown plug on the back of the light cluster.  The green plug is the piggy-back for the other light cluster, and the small yellow plug deals with the indicators.  What I didn't know is which of the pins on the brown plug related to the brake light and I didn't know where my multimeter was (typically I found it when I was putting tools away after this job was done), so I went the practical approach.  I stuck the wires from the new brake into the slots for the pins on the brown plug until I got a pair that lit the brake light up.  I have no idea if this is good practice, but it seemed low risk as the worst I could theoretically do I assumed was to blow a bulb or a fuse.  After a bit of trial and error, the only pins that operated the brakes were these.

Then I had to figure out the best way to connect the new and old wiring.  After a bit of jiggery pokery, I figured out that you can prise the black part of the plug out which gives you access to the back of the pins.  The factory wiring just pushes into these pins to make a connection so, in theory, it made sense for me to do the same and stack the new wires on the old ones.  A little nerve wracking prising the plug apart since I had nothing to replace it with, I found the best way was to prise it up with a screwdriver from each narrow side and then push the locking tabs in as you go, eventually it pops out.  Then fiddle about with the new wire and test several times to make sure you had a good connection before putting the black insert back in.  I did have to resort to a tool not commonly found in an electrician's kit which was a small C clamp so that I could press the black insert home, using pliers or similar got one side in and not the other, so this worked quite well.

More testing after that and the light was still working reliably.  Good.  Next was to tidy away the wiring.  I didn't have the sort of clips I wanted for the one short bit of exposed wiring at the top of the tailgate, so I improvised with a clip I did have that was just bit enough.  Eventually I'll replace this with some more suitable edge clips.

The extra wire was tidied away and given a cable tie so it didn't end up hanging down outside the trim.  Yes that is a recycled cable tie, something I picked up from @KruJoe

I carefully reinstalled the trim I'd disturbed and the wire was mostly invisible, quite a satisfactory job.  Further testing showed that the light was still working.  There's no trim to hide the wire behind in the side pockets in the boot, what you see in there is literally the bodywork of the car.  Fortunately there's a trim bracket you can hook the wire over to keep it close to the back of the light cluster so unless you go looking for it, you don't see the wire.

I'd already figured out any rear visibility issues, as in what it blocked from inside the car and where it was most visible from the outside of the car, which is why I settled on having it at the top of the screen instead of at the bottom.  I did double-check this before instalation since there was enough wire to put the light at the bottom of the screen, it just didn't work as well there.

It's an unobtrusive bit of kit that gives me a little more peace of mind since I now have a brake light at eye level for other drivers.  I like that it's not very obvious inside, or outside, of the car.  Oh, and I suppose I should show it lit just to prove it does work.  A little difficult to see in the daytime with the tailgate open, at night I'm sure it'll be much more obvious.

[vulgalour]

Spurred on by the success of that brake light install, I was delighted when the new fuel filter arrived today.  I was very hopeful that I'd finally get to the bottom of this air leak that was making the car undriveable.  Fitting the new filter gave me a eureka moment on the fuel pipe routing between injector pump and fuel filter housing so I finally resolved that.  Everything is a bit snug, but nothing is kinked or chafing so that'll do me fine.  The filter isn't on upside down, that's the only way up it goes, for some reason the print on it is upside down to usual.  The new seals with the new filter fitted very well and, after bleeding the air out and priming the system, the car did eventually start and none of this leaked.

Then it stopped running.  It was an absolute bear to get going again, much worse than usual, and I was having trouble getting it to idle long enough for me to get my eyeballs and earholes into the engine bay to try and find any visual or audible leaks.  One injector looked a bit damp, but that soon dried off, I couldn't see any diesel coming up from the engine side, or down from the pipe side so I'm not sure what that's about, maybe a duff injector seal?

I triple checked every connection, every hose, trying to find somewhere the air was getting in or diesel was getting out and there just wasn't anything to see.  I wondered if it just needed a bit of a blat up and down the street to maybe clear some air out so after checking for the umpteenth time that there were no leaks, I did that.  Particularly pleased at how much better the ANT brand (never heard of them before) fuel filter and seals seem to fit than the FRAM one I had on there previously.  Pretty disappointed with the FRAM one in all honesty.

Anyway, the car would run if you held the gears and gave it a lot of throttle, come off the throttle too quick and it would just die, whether you were at idle or not.  Then it just wouldn't want to restart at all.  At one point it was so unwilling to start I began to wonder if I was going to have to push it home and then it started chugging slowly and puffing clouds of smoke, and then very suddenly decided it was fine and set off quite happily.  It's impossible to drive now.  Parked up, the car died before I even got my hand near the ignition key, and checked for leaks again.  This time I found that all under the injector pump is wet with diesel.  It's not pouring out, it's just a constant weep here.  Also, on some of the attempts to reprime I could hear the telltale squeak of air being sucked in somewhere in the vicinity of the pump, it wasn't the fuel filter like before, the nose was definitely coming from the injector pump on the fuel inlet side of it so I suspect that's where the leak is.

I also had a dig in the kitchen for a potato so I could take a video of it running for diagnostic purposes.  If I had an apple I would have used that instead, I hear they do better quality video.

 

 

[Broadsword]

So do you think all these slight running issues have at least in part been because of a gradually failing injector pump (or seals within) all along? Then again it's strange that the fuel filter change would finish it off like that if the pump is indeed faulty.

[vulgalour]

I think something has been leaking and slowly getting worse combined with the leaks we've already found and rectified.  Whatever the original leak is has just continued getting worse and now it's pretty much at the point of total failure.  The trouble is, I don't know what that something is yet.

[Talbot]

On 4/4/2020 at 1:41 PM, Cleon-Fonte said:

Has the fuel heater down the back of the engine been blanked off yet? It's a well documented air ingress point and bypassing it shouldn't make any difference.

This, this and this again.

All XUD engines from this era had a sintered aluminium fuel pre-heater bolted on to the water pump inlet elbow, IE right down the back of the engine in the most inaccessible  area of evAR.  They go porous for a laugh and will give all the same symptoms you are currently getting.  Trace your pipework from the tank up to the filter head and be absolutely sure that this has been bypassed.   I used to bypass these even before they failed as it was very much a case of "when" rather than "if"
 

Another trick to find this diesel leak is to put a bit of pressure in the fuel system.  Easiest way is to find the tank breather and shove about 1psi of compressed air into it.  Any leak, even on the suction side of the injection pump, will then weep diesel out.  Found a few very odd leaks this way.

[vulgalour]

As far as I know, the pre-heater hasn't been bypassed and it is on the list.  Fuel filter was ahead of it since we were addressing leaks I knew I had.  My gut feeling is still that it's a fault with the injector pump because that's where the noises are and that's where there's a visible weep of diesel.  I will be getting under the car to check the rest of the system - though I found nothing amiss on previous investigations - and will of course report back.

My checklist for leaks are:

• pre-heater thing that always leaks
• injector pump, because it seems to actually have a leak
• injectors, because injectors wear out
• Any other pipes I haven't yet replaced

I've already replaced and hopefully ruled out:

• fuel filter primer
• fuel filter and sealing rings
• rubber fuel line into and out of fuel filter
• injector leak off hoses

It's slow going because every time I've thought I've found the leak, it's reappeared usually somewhere else.  I wish I was off work so I could devote more time to this, I had completely expected work to dry up and give me some free time and it just hasn't.  I've also only got so much patience with my hands and tools being covered in diesel, even when wearing gloves, so that's not helping.

 

[Talbot]

Bear in mind that everything after the lift pump in the injection pump will not cause the symptoms you're experiencing.  It can only be the lift pump itself or the inlet pipework between the tank and the pump.  Everything else will show up as a diesel leak, but not affect the running of the engine.

Injectors wear out, but the symptoms don't come and go.  If they were worn and had bad spray patterns, they would just give you consistent crappy running.

Even the injector leak-off pipes shouldn't give you the running problems you currently have.  Starting problems, yes, as it would allow fuel to drain back while the engine is off, but once running it should not then stall again.

One thing that you could do to negate any other problems is run the engine from a slave tank (IE a fuel can) that is above the height of the injection pump.  If the engine then idles and runs without stalling, you have your issue.  If it still dies, then it's not a fuel pipework problem.

[vulgalour]

I'll give the jerry can idea a go at some point, it would help with diagnosis perhaps.  It's a frustrating one and I've been avoiding it since my last post and instead trying to do some research, thusly.  The following is copy-pasted from another forum.

Having gone over the various tips and advice, I was all geared up to try and do this and then realised I can't for one reason: I have no idea what I'm looking at.  After much searching through the manual, the forum, the internet, I can find nothing conclusive about what the fuel preheater looks like, where its located, or how I might bypass it.  All I can find is people saying "simply bypass the preheater".

My best guess is that it's the silver square-ish box to the bottom right of this image.

But also that the one on my car isn't going to be that design because it's older, so it's more likely this black one in the same location.

The reason for me thinking it's that piece is that's the side of the engine the fuel lines run, and more people say it's "on the back of the engine" as the location than anything else.  Some people have told me it's near the fuel tank, but that doesn't line up with anything I can find.  Unless I'm being spectacularly blind, I can find no reference to this part at all in the Haynes manual, and a search online to try and find anyone stocking a replacement (so that I can at least see what the part looks like) has been equally fruitless.

So, how do I "simply bypass the preheater"?  What does it look like?  Where is it located?  I've looked under the car and while I can see something that looks like it might be that thing, without knowing if it is that thing I don't want to go unplugging stuff until I know at least a little bit what I'm doing.

[vulgalour]

Turns out, my car doesn't actually appear to have a fuel preheater so there's nothing to bypass.  That rules out that as being the item at fault at least.  I'll come back to the leak finding in a moment because one thing that arrived today was a new washer spray bar that was kindly donated by @Meter rat since he had a spare.  Optimistically I thought this would be a straight swap, instead it needed a little adjustment.  This is the aluminium type rather than the original fitment plastic hose type.  My original spray bar had already been given some gaffer tape on the bend by a previous owner which had worked okay, but now it had split in another place and wasn't doing its job so well.  Removal is straightforward, it's held on with three plastic clips to the wiper arm itself.  Here they are side-by-side.

The aluminium one is slightly thicker in diameter and because of how the end is capped off, it won't fit through the plastic clips.  I couldn't reuse the end cap from my original spray bar as it was incredibly brittle and would probably have broken up if I just trimmed off the and of the aluminium pipe and inserted it.  I didn't have any other suitable end cap so I looked for an alternative option.

The answer was to use a fine tooth saw to carefully cut a slot in the side of the clip.  I chose the side since it would line up with the squashed end of the new pipe and it shouldn't compromise the strength of the plastic clip too badly.  The clips didn't seem very brittle, so I felt confident they'd be springy enough to push the new pipe into place and not break.

Yep, that worked okay.  The third clip is a U shape so didn't need any modification, the only issue with that one is that the outer diameter of the aluminium bar is fractionally larger than the original spray bar so it was a bit of a fight to get the clip to lock in place on the wiper arm.  It was otherwise fairly plain sailing.

I'm happy to report the new spray bar works much better than the old one, putting screen wash down of sufficient quantity for the whole length of the blade that it no longer drags the blade along a dry screen when you hit the washers.  That's a satisfying little job to have done and since I had some more lunch break free I thought I'd see about tracking down that air leak.  What I did learn is that my car doesn't actually have a fuel preheater, which is the item I've been told repeatedly is what's likely at fault.  I had a right job trying to even find a picture of what one of the preheaters looks like since it's on the side of the engine hardly anyone photographs and it's not even mentioned in the manuals I've got.  Anyway, my car not having one rules out that being the problem doesn't it?

I did eventually get the car to start with a big cloud of smoke and it stank of veg oil, something it hasn't done since I first got the car on the road and which was a bit surprising.  I just about got the car to idle long enough to start looking and listening for the air leak and found I was having to use the fuel primer button almost constantly just to keep the engine idling while I was looking for the issue.  Eventually I noticed the diesel appearing under the pump again so I hoped I'd see some diesel from another location to show me where that was coming from.

I knew the diesel leak was no higher than the injection pump, I knew it was on that side of the engine, and I knew it was at the front of the engine, just from where the diesel was present.  Then finally I saw where it was coming from.  Every time I primed the fuel with the button to get it idling properly I noticed the top of the injector pump where the throttle bracket fixes was wet.  Some tissue at the joint after drying it off confirmed the suspicion of a leak.

It's not a big leak, but when you get this area to actually start leaking diesel you can then trace the route it takes which is to go down the spring under this bracket, down the front of the injector pump, underneath it to the bracket, and then down the block on the timing belt side.  It then runs down the sump, to the engine mount, and drips on the floor.  Interestingly, with the car turned off, when you prime the fuel system you can hear air being sucked into the injection pump, presumably at the same location, and when you stop hearing the air and go back to the primer button there's absolutely no resistance to it until you reprime and the symptom repeats.

I hope this is actually the air leak and that there isn't another one waiting somewhere.  I'm hoping that I can redo the seals myself with one of the kits that you can get for just this purpose rather than having to try and arrange getting the car to a specialist to sort it out.  The pump seems a fairly straightforward mechanical thing providing you heed the warnings on setting it up correctly if it does need to come off the car to be done.  I also suspect that this issue is down to the car having been run on used veg oil in the past without the proper care taken over filtration.

[plasticvandan]

I don't pretend to understand diesels,bit I've always been of the opinion that on a car,if fluid is leaking out,air can get in,so would summise any diesel leak is an air leak as well