Figured I'd start a new thread for this, as it is neither M57 engine conversion related or really relevant to anything else I'm doing.
As some of you might know, I've had a split charge setup for a few years now after Marty FINALLY convinced me to get around to it. It is mainly for running my Waeco compressor fridge for longer periods of time without worrying about the starting battery. It has never been to combat any battery drain issues or anything janky like that - in fact it is isolated whenever the engine isn't running through a VSR.
It occurred to me though, now that I no longer need the LPG tank, I can remove said tank and refit a spare tyre. But then I got to thinking a bit more... I've never had a spare wheel, and have a few cans of goop and my TMax compressor should it come to it. So... why don't I make use of the space for something else?
The plan is to build a custom frame to live in the wheel well area that will hold not one but two 019 sized 110ah leisure / deep cycle batteries, plus a pure sine wave inverter. The split charge kit will also be relocated to this area too. Outlets for 12v will be mounted into the load space in a convenient spot, one for the fridge, and one for a 50amp take off - both using Anderson SB50 connectors, because I like them. A 230v outlet will also be present, and I have plans for another one elsewhere down the line.
First things first... the LPG tank needed to come out. Mine had been held in with two massive bolts through to a steel plate underneath, and then expanding foam was used to stick it down... made removing it a bit of a tit.
You can see the semi-temporary arrangement I had for securing the current battery. The straps are held to the body - they're not just wrapped around it :)
Ideally I need to cut a section of the floor out and sort a new plate to deal with the mangled holes left from the LPG install, along with a drain of some kind.
This was oddly satisfying to clean up.
I figured rather than try and make a battery tray specifically fit the frame I make to bolt into the wheel well, I'd start with a tray alone and then build the framework and mountings to fit the floor of the wheel well second.
Yes - I am aware the tie down bars don't allow for batteries of different heights. Conveniently... the two new batteries will be a matched pair and thus the same height :)
The rods screw into captive nuts on the tray, and I will likely weld the top nuts to the rods making them long bolts effectively - or something like that. I've yet to add a few bits of flat bar into the base to support the underside of the batteries a bit more - will do that before paint.
I'm happy with how its come out. Next is to look at the top bit of framework that will support the actual load space floor panel, and tie it in with the battery tray.
Would someone be able to take a picture of the spare wheel well for me, with no spare wheel or lpg tank present?
Currently I still have a tank in mine that needs to go, and I was originally just going to stick a spare in... But now I have other plans for the space, but could do with some inspiration in the form of knowing what the actual surface underneath is like before I get around to digging the tank out.
Does anyone make a twin exhaust setup for a P38 that actually fits, that isn't genuine LR prices?
Just 'fitted' an allmakes rear section and its absolute crap. Admittedly, not quite as bad as the eBay stainless special. But the welder still had to come out to completely rearrange one hanger, and the backbox on the opposite side is now resting nicely against the tie down loop.
I have a new noise that has developed... and I am slightly stumped currently. Noise starts occurring towards the end of the clip and it sounds exactly like that in person. Audible inside the car clearly.
It only happens under load - in the video it is in drive with handbrake on and another foot hard on the brake. So it isn't UJs, or anything post autobox output.
It starts about mid throttle and between 2-3k. It might persist higher in the rev range but I've been driving sensibly to avoid having two cars off the road. It is there approx 50% of the time too. Lift off and it stops immediately.
It is NOT the belt or any ancillary - it persists with the belt off. I wish it was.
Engine hot or cold.
It appeared to be worse on gas than petrol, but I think that is placebo as it happens on either fuel.
It appears to be on the RH/drivers side, but as with a lot of noises it sounds like it could be underneath, to that side, or on top. But, its definitely further away than the LH/passenger side.
In neutral/park however - gone. Revs up and down sounding lovely.
The most annoying thing about this particular irksome noise, is I am sure I had exactly the same thing with the first engine on my first P38... and I never got to the bottom of it. I'm pretty sure that was 'solved' when it had a replacement engine dropped in. It also had a set of headers already on it. I can't see any evidence of a leak from the little you can see with heat shields in place.
Anybody come across this before?
This may upset the purists... but I've had a bit of an itch to put a BMW M57 diesel engine into a P38 for a while, and after thinking about it more and more - I think its time to start work on it. This may be a lengthy first post. Doesn't really fit into oily bits or electrickery - it will certainly contain both.
My P38 has a Bosch/Thor 4.6 engine that has seen better days. It's biggest problem is a suspected crack behind the liner of cylinder #6. For over a year I struggled with coolant being pushed out random places. Each time I 'fixed' one leak, it would pop up somewhere else. After it started missing badly at startup, which turned out to be a single cylinder, I found #6 spark plug was rusting... Those that have seen the deck of the block should know there is no way coolant should be able to get into that cylinder unless its coming through somewhere very bad.
So a top hat block would be the way forward - perfectly reasonable solution. Except I had just bought my first house, and the thought of sinking circa £4k into it when all is said and done wasn't going to happen. That left me with the initial options of scrap it, put a used engine in it, or park it and leave it. Scrapping it was obviously out, and I've done the used engine thing before with less than great results. Parking it up also didn't really work as I needed a big vehicle for getting things done.
I can't remember how I got the idea, but I figured there was little to lose in trying a chemical solution... it was already buggered, even if it ended up needing a new radiator and heater matrix down the line... it would be a small price to pay against the £4k of new engine. Settled on pure water glass, which is the main part of products like 'Steel seal' etc, but purchased as the chemical it is instead of a branded product is significantly cheaper! I've lost track of how long ago that was, but its over a year and between 5-10k miles now. No coolant loss, no leaking, no rusting plug, no missing.
So while it is, for the moment, keeping its coolant in check, its most likely on borrowed time. It's still burning a fair bit of oil and chucking more of it out down the side of the engine despite having rocker and valley gaskets done when it was pulled for the shattered flex plate. Breathers aren't blocked, so I must have done something wrong with one of the gaskets.
On top of that, LPG is becoming scarcer in my area. I have only two stations that do it that are worth going to now. One is expensive, and the other is out of my way and I don't trust that either will carry on supplying it for long. When LPG goes, my usage of the RR will have to drop significantly if forced to run on petrol.
And one final nail - it is bloody slow. Marty's is certainly quicker with its new engine and high torque cam, so mine is likely now an example of a probably less than stellar engine in terms of lost ponies. I know they're not sporty vehicles, but for the size of engine, the fuel consumption, the amount of noise it makes, it just needs more power.
And as it happens, I now have a superb condition BMW M57 engine from my late E39 530D. This is a common engine swapped into various LR vehicles, including P38s. Mine is the 194hp/390nm version. Less than the "225" hp my V8 may have once had, but more torque, and this is before a mild remap. And it stands a better chance of still having near its original figure as it stands!
Unfortunately my E39 met its demise in December of last year. No one was hurt (I wasn't even in it!), but the car was beyond repair - which became more apparent on pulling the engine. My car hit the car in front, and another hit it from behind. The front impact was so severe, despite not looking that bad, it slammed the engine backwards smashing an engine mount, and the gearbox crossmember. Despite all that... when the front of the engine was cleared and power was applied directly, it started straight up and purred like it always did. 168k on the car. I've genuinely never had to top off the oil or coolant while owning that car - and there was virtually no oil sat in the intake either like most diesels. I sorted some of the common M57 issues out in my ownership as preventative maintenance too. It had its swirl flaps taken out a couple of years ago, as well as the EGR disabled to prevent nasty intake buildup, and the oil breather was changed from a filter type that can clog to a cyclonic type etc.
Removing the engine and everything else needed, plus anything of use/value from the rest of the car. The upside of starting with a donor vehicle like this is I have all of the necessary wiring, ECUs, keys etc - and owning the car I know the condition of things.
What I will say is the viscous fans on these things are bloody strong. Power steering pump (further back than the fan, obviously), completely smashed... fan? spins true.
As I said, the P38 has seen M57 swaps before, but what I have never seen is a proper write up of how it was done, what challenges needed to be overcome. What I have seen a number of examples of is bodge jobs and half-finished projects that seem to stop being updated. Probably because they came up against something that couldn't be overcome. Certainly, if starting with a manual vehicle, it is a lot more straight forward.
Alas... I have and want a working automatic. I want everything to work as it originally did inside the car. Dials, gauges, HEVAC, heated seats+windscreen, air conditioning, cruise control. I have already started work on planning how each of these needs interfacing - I will post up how I go about these. It's a Range Rover - if the toys don't work, you might as well start with a Disco.
Truthfully the only thing that currently concerns me is the auto box control. One way to go about it is a Compushift aftermarket controller. But they are expensive, and that is going to be the last resort at this stage.
Because I'm still working on my house and garden at the moment, the engine is currently sat in storage. I have the engine ECU, immobiliser (EWS), key transponder pickup and loom all inside to start work on when the weather stops play in the garden. You can have the engine ECUs reworked to programme out the immobiliser entirely, however as I have the matching ECU, EWS and key, for the time being I will packaging the three together to let the engine run. For one, its a cost I don't need to fork out for initially, and by getting it running with the original setup, if I have any problems from the first start, I know it will be something I've done, rather than someone else.
The complete loom from the front half of the E39:
Reduced to what is actually needed to just run the engine ECU. ECU, EWS, key transponder pickup, drive by wire throttle, OBD socket:
These will form the basis of the vehicle interface loom. The loom that powers the ECU isn't shown as I left it on top of the engine, but its self explanatory. The interface loom connects the engine ECU, the EWS and key pickup, and the drive by wire throttle/accelerator pedal. It will also have outputs for the oil light on the dash, the alternator light, CAN bus for the auto box ECU (via whatever means I come up with to interface it to the gearbox), temp gauge, engine speed, things like that.
In terms of physically getting the engine into the P38 bay, there are a couple of hurdles I believe I need to overcome.
Mating to the gearbox is going to need an adapter plate to use the 4HP24 gearbox and V8 torque converter. These are available from a place called rallyraid, though I need to email them to check if the specific gearbox I have is suitable or if I need to find a particular gearbox and torque converter to suit.
After that, one of the engine mounts can be used from an M51 I believe, but the turbo/left/drivers (RHD) side will need fabricating, and the turbo actuator modifying.
The sump will need customising. To clear the bump stops, I've seen people use half an M51 sump and half an (I think) e39 M57 sump welded together. That's no issue. I've heard of others putting extended bump stops in place... but that's janky.
Once the engine is actually sat in place and mated up to the gearbox, I'm actually not concerned by anything else mechanical. I'll need an intercooler and to move the autbox cooler. The engine oil cooler won't be needed as the engine has an oil to water heat exchanger. I'll probably change the main radiator for a GEMS style one, as the top hose outlet on the M57 is on the right/passenger (RHD) side of the engine near the top. My electric fan setup will be staying, so the viscous fan will be removed from the engine.
The air conditioning is going to need some custom pipework I suspect, but that will be a future problem.
As I said... a long first post. But that's a bit of a splurge on my current plans/thoughts/reasoning. Yes, I'll lose the V8 soundtrack, but a common rail straight 6 diesel isn't the worst sounding thing in the world. It will also sound like a diesel at idle and have a reason for doing so, unlike my current V8 :) What I'll in theory gain is power, fuel economy, and reliability. I drive my P38 daily currently, and while I'm not worried about it letting me down at random - I can't help but think I'd have more confidence in the BMW engine.
So after a year or so of having half of my crap stainless exhaust system on my P38, I finally want to sort it - and that means going back to a 'standard' rear section, with a straight through pipe in the middle. The latter is already sorted. What I need is the rear section...
It seems a lot of aftermarket stuff is hit and miss, and what I want to avoid is something that doesn't fit or sit level again... with that in mind, has anyone tried one of these?
My 2015 vintage condenser has sadly succumbed to incontinence, in the same week that my BMW rubbed through one of the lines and also emptied itself of its precious refrigerant.
Anyway - back to coolpartsuk on eBay and ordered another one. When this turned up, I was sure it was the wrong one...
Upside down and the fact its narrower with pointy outy brackets threw me off... but it does in fact fit! And as a bonus, the fan mounting holes line up perfectly, whereas the previous couple of aftermarket in the 'old style' have been a bit of hit and miss... mostly miss.
Has held vacuum, so off to get it and the BMW gassed at somepoint.
While I'm repairing my nudge bar, I could do with a measurement of the depth available for spot lights - ie the distance between the front edge and the radiator grille with the bar fitted to the vehicle. I know the LR Safari 5000 lights fit - but I want to fit something else, but they're a bit deeper.
If anyone can oblige that would be much appreciated :)
Pic for attention:
Much like the mud guards... these things are horrendous for rusting under the foam/rubber and quickly becoming beyond repair.
I have an oil leak (standard fitment, of course) that I can't work out where is originating from...
The starter is getting covered in oil, to the point the frame rail immediately opposite it is getting wet, and the exhaust heat shield gets a build up that burns off.
The rocker covers are, for once, not leaking, and I've cleaned/degreased both sides of the engine since last doing them.
Looking up from underneath, the oil does not appear to be coming from the front of the engine, but about half way back, it suddenly is quite wet:
Front end is dry:
If it were the valley gasket at the back of the engine, I can't see how oil would make it this far forward? I'm also not dropping much on the ground, the odd drop. I think most is worryingly ending up being burnt off. I thought head gasket perhaps, but from what I can see there is only one oil feed up to the heads, and that is on the front end of the engine above the cylinders...
Today I had my windscreen replaced, by the company my insurer provides - Nationwide Motorglass.
I left the car in a nice open space with plenty of room around it, and let the guy get on with it. He let me know how long it would be etc, all fine. I checked with him that they'd supplied a heated windscreen, and not made a mistake with the wrong glass etc. All fine.
Hour or so goes by, and its all done. No problems mentioned, told to leave time before driving, longer before washing etc. Anyway - I get home, pop the bonnet to check no dislodged trims. Notice a screw missing, but no biggy.
My old heated windscreen had about 3 lines total that worked - and was open circuit one side, so it basically didn't work. I tested the resistance from the relay sockets to ground to check it was all connected okay (not exactly the weather to be testing it, and who knows if it should be left for the adhesive to cure fully before using it). One side open circuit, the other, 1.4Mohms. errrrrrrr... that isn't right.
Figured fine - it hasn't been plugged in properly. So I pop the strip at the bottom of the windscreen off carefully... and the air turns blue.
For those that haven't seen this area before... at the bottom of the glass in the middle of the screen should be two black wires - the grounds for the two halves of the screen. Both, as you can see, have been cut clean off. The black wire visible is the remains of one ground wire to the old glass.
This is the remains of the passenger side positive cable, again, from the old glass. This was presumably the side giving me 1.4mohm, as it was flapping around touching the body/painted surfaces. Brilliant - so a cable that would properly eventually wear through the paint and short out.
What he has done is pull the old glass out of the body, ripping off the cables in the process. He has then cut off all of the wires on the new glass, and bonded it in. What the fuck.
I can only assume he has ripped the old glass out before realising some of the screws holding the scuttle panel in were rusty, but frankly you could still get the positives in place and connected even so. The grounds a bit tricker maybe. But he should have at that point contacted me, to ask what to do. I would have happily removed the screws myself as I have now done to inspect the damage. The positive loom on the drivers side has had the connector bracket bent, and the rubber cable bung pulled out of the body. Thankfully the plug itself wasn't broken.
I have been in contact with the company, who are sending someone out on Tuesday to 'inspect' it to confirm what I'm saying. If he/they even try and deny he has cut the wires off the new screen, they won't get far:
On Tuesday I'll be leaving the car in our visitor parking, which will cover it entirely in HD CCTV.
I am incensed by this... what was he hoping? That it would get to winter and I just wouldn't notice? It would still come back to his company. How many others does this happen to? Is it just him, is it standard practice when its 'too hard' to do a proper job?
Fucks sake. I hate being watched while I work, so I left him to it - he's a professional, supposedly. Now though... I'll be sat there watching whoever does it next, as well as having it recorded in full view. Sometimes its just easier to be paranoid, can't trust anyone to do a proper bloody job.
For a while now I've had a miss on startup that clears within 10-20 seconds, which new leads hasn't sorted, so I figured/hoped a new set of plugs would sort that when I got around to it, or at worst one of my britpart coil packs was failing. This might still be an entirely unrelated problem, however..
Over the last couple of days I've had a missfire that rapidly got worse, to the point cyl 6 died entirely on my way home from work. Same on LPG and petrol. Plug lead connected fine at both ends, and it was only cyl 6 that was dead and not also a cylinder on the other bank, suggesting investigating the plug end first was the way to go. Pulled the plug... and it looked like this:
These plugs were new in 18 months ago, maybe slightly longer... so while they could do with changing, this looks concerning. I pulled another out and it looked like your typical wear - nothing unusual. #6 though looks like it has been rusting away...
I'm not losing coolant (for once), no steam other than when its humid out and the box has the usual condensation in it. Even if it were coolant, it wouldn't rust, and it should look clean rather than stained I would have thought. So lets say it was straight water in the cooling system, the plug would have to be sat in it to do that.
To further confuse things, when I did a compression test last year, this cylinder had higher compression than the rest - considerably higher if I recall. I didn't have my tester with me last night, just one that was older than me, which read about 150-180 psi but the non-return valve was leaking so didn't see a proper figure. I was mostly interested to see if I'd lost compression entirely at the time on that cylinder.
So I'm not sure what to make of this... conveniently had a spare plug from a Honda engined generator that fit, and its now running on all 8 again as if nothing had happened. Too early to tell on the startup miss, there seems to be little consistency as to when it does that, apart from cold startup.
Not oily, but smelly?
I need to replace my gas filter and the hose between the vaporiser and HD344 injectors... but I'm not entirely sure what size it is, and with the hose in the state its currently in I'd rather not remove it to measure.
I have an OMVL Dream XXI-g vaporiser, which I believe is 12mm. Plenty of filters about that are 12mm too, but I can't find any info on the injectors. I have a feeling they might be 10mm?
Could you possibly take a picture of something for me?
I've just changed my tailgate straps as one snapped a while back.
The replacements I've put on are Bearmach, but both ends have been crimped on in the same orientation, meaning the cable needs to twist for one end to be screwed in. So the first time I close the tailgate, they twisted, and one had a chunk taken out of the rubber/plastic sleeve as it got trapped between the tailgate and body... no amount of changing the twist makes things good - they either get caught in the body or caught in the door seal...
I'll be returning these as they're crap, the ends also don't rotate freely because the washer type thing is too big and it ends up clamping down on itself.
Has anyone bought any that are decent, if so, who/what/where? :) Specifically avoided Britpart and still ended up with junk from Bearmach... sad times.
Checking on things today and noticed something looked a bit... odd
I need/want to pot some spade terminals in a plastic connector, that will be subject to relatively high temperatures - around 100c (guess what, ha).
So far as I'm aware, most 2 part epoxy resins won't remain all that solid that hot. Any suggestions on something that will bond and hold up well?
Could someone confirm the below for me? My top hose persists in leaking, and now that my thermostat is stuck open I'm going to change it for some siliconey bits.
On my Thor, the outlet pipe appears to be 32mm OD. The inlet to the radiator appears to be 36mm OD however. Does anyone have a Thor radiator sitting about that they could measure properly for me? I don't want to take the hose off just yet.
With a couple of corners and a reducer I can make that work if it is the case. I can get 32mm and 35mm ID silicone hoses, but before ordering I figured I'd check!
Bit of a long post, but it might be of interest... I know this is a bit of a controversial topic, and I get why. The viscous fan when working correctly, is hard to beat.
Mine however, did not. Well it did - far too much. The fan is/was fully locked up I'd say 90-95% of the time, and resulting in a loss of power, MPG and the engine never got above 85-7c. Those of you that have seen/heard my car know it isn't that quiet. No centre silencer improves the V8 rumble no end, but its no fun when your viscous fan drowns it out entirely!
The ideal electric replacement fan would, by all accounts, be the 18" Lincoln Mk VIII fan found on various vehicles across the pond. Alledgedly rated at 4000CFM or so. Getting one over there is simple, getting it over here would be £200-250... err... no.
Looking at generic aftermarket options, Spal do a 16" 'HO' high output fan, that does about 3000CFM. I couldn't even find a price on that, so declared it unobtainium. All others I've looked at seem to top out around 2000CFM. And current draw on those topped out at about 10amps, which seemed a bit too good to be true.
A bit more googling looking at OEM fans pointed me at a pretty readily available Volvo 850/940/S70 fan... the internet suggests on low speed, its around 2500CFM, and on high its around 3300CFM. Best bit is, its about £30 on ebay, and another £15 for the Volvo relay module, which is a handy box that a) handles the current of the fan on high (about 30 amps running), and you just ground either the low or high speed selection to start the fan. A handy feature is high speed always takes priority - so if you hook low speed up to say, come on with air conditioning, and then have a thermostat for engine cooling on the high speed, the high always comes on regardless of what the low speed is doing.
It's a bit smaller than the mahoosive viscous fan, but not overly so:
I wanted a cowling/shroud that would get the fan pulling air across the whole radiator surface. Take one 600x600 network cabinet lid, and a bit of steel from one of the doors, and you're left with this:
And some fettling later. Sadly I didn't remember to take any pictures of the cowling with the fan in place, and the pegs on the bottom that fit into the standard radiator cowling mounts. The ears on the top are used to bolt the cowling to the radiator mount brackets - so the weight is hanging off the mounts holding the radiator, rather than the radiator itself. It isn't actually that heavy anyway.
Plenty of room!
The relay module can be wired up using 10mm spade crimps for the positive feed - the fan plugs straight in. The ground goes to the fan directly, again a 10mm spade fits nicely. The only problem is the speed selection that has round pins. I soldered some wires onto some red bullets, crimped them a bit smaller, pushed onto the pins in the module socket, and then filled with resin. Don't want them falling off!
Currently I don't have a thermostat - so I'm grounding the low speed before I set off and leaving it running. It's in the post...
Today it has been 17-18c all day, and I've had the fan running on low while driving around town, hooning it a bit, and letting it idle. At idle, it will keep the coolant temp down at 87c, with the A/C on too. Once I get the thermostat and can set the on/off points, it should cycle and keep the thing running proper temperature.
Best bit... I can hear my V8 again! And I no longer sound like a Nissan Navara pulling away...
Sad time. Had a phone call from my dad today (while in the back of my P38, fixing various issues, naturally...), and our red P38 had decided to get rather toasty, having lost all of its coolant rather rapidly.
Find it in a car park, and the drain bung on the radiator looks as if it had sheared off. Interestingly having retraced the 2 miles route from the last place it was parked up, we found no trace of a trail or puddle of coolant, leaving me to believe it was very hot when the bung let go, and left as steam. Anyway - popped into the Range and found a 1/2" BSP bung that did the job with some PTFE tape, and filled it up with water. Transpires the thermostat is stuck... coolant up to 96c and the radiator is cold from below the top tank to the bottom. I figure, the stat didn't open, temperature and pressure went up, and an overly tight drain plug let go first. Gave up and towed it home (flat towing a P38... that's a noticeable lump being dragged behind!)
Good news is, no bubbling in the expansion tank while letting it idle, no steam out the back, and no odd exhaust like noises from around the engine. The bad news is however, while it was running and way too hot, the first thing my dad noticed was it was making a loud clonking/knocking noise, and then he noticed it was hot... not sure if it was down on power or not.
The bad news now, is at any increase in engine speed, there is a strange squeal/squeak noise from the engine that is not coming from the belt, and I'm not sure what it is... I need to record it, but would anyone have any ideas what it might be? It certainly wasn't there a week ago when I last drove it.
More of a tale for your amusement, as the offending blighter of a sensor has now been evicted from its exhaust bung, and reduced to many small pieces...
My parent's P38 has had a bit of a bad time lately - tried setting fire to itself twice, once with fuel, then with a locked up caliper. New petrol line, entire ignition system, new front-rear brake lines, flexis, rear calipers, disks, pads... and then the bastard still refused to run right. Lean on bank 1 permanently. Lambda sensor looked like the culprit - refused to shift from 0v despite firing on all cylinders.
So... a new sensor it is. Pop the old one out, pop new one in, job done. Or not. With myself under the car pushing with my foot against the spanner, all I managed to do was round off the nut on the sensor. With a bottle jack forcing the spanner upwards, the car was lifting before the bottle jack eventually gave up, and I rounded another side off...
Friend of a friend offered to help - I think this car may no longer be welcome there! Even cherry red with grips, it still wouldn't shift. So, cross member off, exhaust studs all removed, and the centre box clamping plates cut through. On the bench, even more heat and a 2ft bar welded to the remains of the sensor - nope. Eventually, after the welds on the bar broke twice, it started to move with some persuasion from a set of stilsons.
Before it came out though... I noticed something:
I sent that photo to Marty while the sensor was still being massaged, and he said something about gaskets, and I realised... there was never any gasket on this side -_- I guess, had the sensor actually come out without a fight on the car, who knows how long it would have taken to find the exhaust leak, that was likely the problem all along...
But hey. Managed to find a nut that the new sensor threaded onto nicely, which was then welded on top of the old bung. New exhaust studs, a pair of new gaskets (ho hum, totally haven't been here before, prepared for this sort of crap these days), some nice work on the centre box clamps, and one adaptive reset later, it runs properly!