1992 Jaguar XJ40 SuperTurboDiesel

Ah squirreled away in the technical pages I tend to loiter around the project threads page, must venture out every now and again

Yeah the M57 isn't exactly a rev-hungry beast. Haven't really come across a diesel that is apart from the OM606/605, which is part of the reason they make so much power. You can get cams for the M57, but not sure if they do anything for the redline though. Not that the AJ6 revved particularly high either (5500rpm), so the rev gauges are pretty well matched.

Actually, just in case it interest anyone, I've been trying to do some research into the internal forces in various engines to see if I can work out what revs different engines can reach by comparison to other similar ones (either of the same type, or different but similar ones). It was all in the effort of trying to get a higher revving AJ6, but as I compulsively collect data it's ended up with most I6s of note, a fair few V6s, and a couple of V8s/I4s. There's some estimation in there (e.g. 2/3rds conrod weight is rotational), but a lot is solid.

It's nuts some of the internal forces, and how much these can vary between slightly different engine setups. The critical factors I've found are reciprocating weight at the big end (can be up to 3.5 tons!) and surface speed of the main bearings (typically 8m/s for stuff near the limit, but some Jag V12s can get up to 11m/s!). I was also interested in pin diameter vs piston reciprocating weight, which is similarly nuts (can be up to 2 tons on an 22mm hollow tube!).

Here's a link to it if anyone's interested.

Getting a clear picture is largely dependent on some kind soul having measured complete pistons and complete conrods separately, so if anyone has any measured that'd be amazingly helpful!

One of the key bits missing Triumph-wise is a 2.0l I6 piston weight if you know it Nick. There's lots of info about, but not that!

Simon

Darkside Developments extend the rev limiter from 5,000 to 5,200 on the 1.9 and 2.0 TDI PD units. Their BKD Jetta made 343bhp!

Yeah it's a bit nuts how much power you can get out of oil burners now. One of the reasons I went with the M57!

Didn't know that you could get the JTDs up that high though! I knew you could get mid-350s on the newer 20v versions, but 400-500 is pushing as much as people are getting out of M57s with 0.6l more displacement. Loved the 10v version in my dad's 156 when I was borrowing that. Nicest sounding diesel I've every heard. Proper Quattro-esque warble.

Latest updates on the Jag now that the starting conundrum has been solved I can move onto the last of the suspension work. First off is replacing the rear carrier bearings (a set of needle-rollers between the rear suspension lower arms and the rear suspension upright). Didn't get off to a great start as I bought the wrong bearings!



There's a degree of confusion with XJ40 parts as the bits on later cars ('94, and I think '93 for some bits) are interchangeable with later X300 bits but not the earlier cars. Late XJ40s are pretty much X300s under the skin in a lot of respects, including rear suspension. Key differences are the lower wishbone which is a tubular cast thing on X300s, but is a stamped A-arm on most XJ40s.

Turns out the bearings are different as well. The difference in height is subtle, but enough that the carrier won't fit back into the wishbone (and the through-bolt is a different diameter too).

With the right bearings ordered I repurposed an old crush-tube as a press tool, and used the through-bolt for centreing.





The old bearings races are a royal pain to get out (there's no machined slot in the casting to let you drive them out, and there's only a little lip around 1/3rd of the circumference). It's typical practice to just leave them in if they're not knackered as it's not a high speed bearing surface at all, so that's what I did!

Next up was filling the gearbox. There's a recommended mix of 50/50 Redline 75w140 NS/Redline D4 ATF that's supposed to reduce the gear chatter you get at idle on single mass flywheels. Filling it was a challenge, but my mum nd sister came to the rescue with an old rapeseed oil can they had for their horses, complete with pump handle!



Worked an absolute treat

The last big job on the car is a front suspension overhaul, so it was about time to get on with that! In case people are unfamiliar with XJ40s, the front springs can be a bit of a challenge. They're curved at quite an angle, obscured by all sorts of stuff in the way, and are mightily beefy springs under a lot of preload.



It's not really possible to get traditional spring compressors on in a safe manner, so there's a factory tool for the job (which is extortionately expensive, although a number of XJ40 clubs have them to loan to people). It's basically a sodding great threaded bar that slots up through a hole in the bottom of the spring pan and locks into the subframe above it, allowing you to wind the spring pan down safely.



As there's a possibility of me doing it multiple times as I sort out spring heights I thought it would be a good idea to make one, as a number of others have done before. Here's the one I came up with:





It's an M20 coarse threaded rod with an 8mm pin pressed into the end to do the locking. For the screw section I drilled a 20mm hole through a 50mm steel ball as the spring pan changes orientation as it drops so needs something that allows for that movement. Below that is one of the wrong rear carrier roller bearings to allow it to turn smoothly (others have used a couple of greased washers, but I had the bearings ad they slotted on perfectly). Then a random bearing race I had in the 'press tools' pile that just so happened to fit the outer race of the carrier bearings, and then a washer and nut.

That threads up through the spring pan and twists 90 degrees to lock into the subframe thusly:




You have to get the car pretty high to do this, which is no problem if you're a proper garage and have a car lift, but is a little tricky in my tabernacle on sloping tarmac! Took it slowly and carefully though and I managed to get there in the end



Quite the angle! About 4" from the tailpipe to the floor :S

I did manage to work out though that a length of 51cm for the M20 rod will still allow the spring pressure to be released, but is about as short as you can reliably go with my bearinged setup. The 8mm needs to be about 30-32mm across to fit in as well.

With that setup, I found you need about 34cm vertically below the spring pan, which puts the bottom end of the tool 19cm out from the plane of the hole. At the angle that the tool slots in at, you need 41.5cm between the bottom of the spring pan and the floor. Bit hard to explain without a diagram, but might help someone in the future!

Lastly, it's a good idea to pop some M8 threaded rod into the bolt holes for the spring pan to guide it down (and back up again) as it does change orientation quite a lot! Also offers a little bit of safety in case something gives way.



On cars with similar setups like Alfa 105 GTVs you can just wind the spring down using threaded rods in the boltholes like this, but I highly doubt they'd survive it on an XJ40. They'd probably shear and send bits of M8 stud and an enormously preloaded spring rebounding into your crotch (which is roughly where all of this lot is pointing while you're undoing it all) :S

Still, all worked very nicely indeed and the springs are now dropped next up is supporting the engine and steering rack so I can pull it out, give it a wire wheel and a paint, then throw it all together with new bushes and lowered springs

Haha I think I still have the Leaper from the Jag that got crushed by a tree. Should attach that and call it a 'special edition'

Not a great deal of progress on the Jag due to various holidays and house stuff, but I have managed to pull the front subframe out ready for de-rusting, painting and re-bushing.



To support the engine I thought I'd make one of those support bar things that sits in the drip channels on the bonnet. Used some 1" box section, a length of ally scaffolding pole, some exhaust u-clamps and some silicone hose to make this:





Forgot to take a picture with it installed, but I've got a couple of ratchet straps to take the load and painted the support brackets. Really must paint more of my home-made tools, makes them look much more professional!

Works well enough, and was worth making one rather than buying it as I made it a couple of inches longer than the ones available commercially and you really need it on an XJ40!

Couple of teething problems though. First is that I need to make the little cutouts where the scaffolding bar sits angled slightly as the line of the wings tapers in on most cars. Second is there's not really a good place to support an M57 now that I've moved the engine mounts around. One side is hooked around an engine mount, but I've had to wrap the other around the alternator which I'm not amazingly happy about. So in this instance it's serving mainly as stabilisation for a jack under the sump, but on a less busy engine it should work rather nicely

Cracking progress. Sorry to hear of the injury, do hope you're healing up ok!

Little more progress on the Jag. First was a little light duties stuff while I recovered, trying to get a working coolant temp sensor for the Jag gauges. I'd initially bought an in-line takeoff for the radiator hose like this guy, but wasn't amazingly keen on the temp reading coming from the other side of the thermostat.

Then, I was scrolling through some of the FB car feeds and spotted someone asking where to take a coolant temp reading on an M57-swapped E34 and someone mentioned the coolant drain plug about halfway up the block. Turns out it's the same M14x1.5 thread as the BMW sensor, which was easy for him but as my Jag sensor is 5/8 UNF I'd have to adapt something. This is what I came up with:




It's a 5/8 UNF female to M14x1.5 male brass adapter jobby, with the bore drilled out ever so slightly to let the Jag sensor fit through. I cut some of the excess threads off the end to let the tip of the Jag sensor poke out a bit, but it'll all probably heatsoak quite effectively anyway (especially as it's right next to the downpipe!).

After that were a few more bits and pieces I'd like to do while the subframe's dropped. First up was the oil pressure sender. As standard, M57s have a boggo on/off switch, but as the XJ40 has a gauge I'd like to use it! The BMW switch is on the underside of the oil filter housing here:



I didn't much like how much space there is around it, so I thought I'd try and find a pressure sender that's the same M12x1.5 thread as the BMW one so I could swap their positions on the little brass tee thingy that I had to buy from Poland because no-one else is selling ones that have M12x1.5 all the way around...



It was at this point that I discovered the little note I'd scribbled down saying 'Jag sender, M12x1.5' was, in fact, quite misinformed. It's a bigger thread, although not quite sure what it is yet. Not a major issue as the Jag senders are notorious for dying (apparently the AJ6 oil pumps produce a lot of vibrations along the oil column that kills senders).



After a fair bit of googling and coming across this thread I plumped for this sender with a range of 33-240 ohms. As the Jag gauge reads from 230 ohms at '2' and 75 ohms at '8' I figured it'd be close enough with a resistor in line.

That goes together like this:



...and in place like so:



It'll be a pain to access after the subframe goes on, but hopefully still possible with crows-feet spanners. The BMW sensor is just about short enough that if you can get the new sender off you can rotate the whole thing round to unscrew it which is lucky. Jury's out on clearance to the engine mount though...



The other thing that needed doing before the subframe goes on is sorting some rust by the front mounts. I'd noticed there was quite a bulge in the metal where the mount sits on one side, meaning there was probably quite advanced rust creeping inbetween the layers there. I was not wrong!




It's amazing how much more volume rust has than steel. Maybe 5mm of rust had formed from a 2mm piece of steel. This is how far it went:



Choppy choppy, weldy weldy, grindy grindy:





Normally I'm against re-making multi-skinned layers, favouring just stepping up the steel thickness and welding in one plate. However, in this area it was a bit tricky to do that and retain the position of the locating tubes for the subframe so I figured I'd just try and do a good job of rust-proofing between the layers. I've got a pic of the 1.5mm covering plate I cut, but not of the zinc primer between or having welded it one, painted and sealanted it so you'll have to just trust that I did it



Although the other side looked alright I wasn't convinced so I chopped that back too.



The rust wasn't as advanced under there, but had spread further back so I ended up chopping off more of the second skin. The thicker inner plate cleaned up well enough with a wire wheel and a linishing disc so I just did the outer plate on that one. No pics, but it's all sorted ready for the subframe to go on, barring any further nasty surprises

I winced at the bit with the broken rib, be careful as if you do yourself a mischief we will all miss the thread updates 😂

Big weekend man! First thing is the propshaft was ready so I trooped up to Bexley to fetch it. Terrible photo, but this is a beefier 35mm centre bearing and a sliding spline section fitted to a Jag centre bearing housing:



If anyone wants to do this in the future then I'm afraid I've no idea what bits they used! I had brought them a 6-speed Transit propshaft to use, but the sliding spline section was too long to fit in the shorter section of prop so they said they'd order in some parts for it. Was too excited and forgot to ask what bits they'd used

The actual bearing itself is from an E46 330d, and presses out neatly from the rubber housing. It's got the right 55mm OD to fit into the Jag carrier which is handy as all the ones I could find for sale with a 35mm ID have a larger OD. Had to buy the whole assembly just for the bearing as no-one would sell be just the bearing itself!

That let me throw the exhaust back together and it was finally ready for a shakedown run! Only issue is that there was a sodding great Jag engine and gearbox in the way



Did give me the opportunity to weigh it though. Complete AJ6 4.0l and getrag 290 in about as heavy of a setup as you can get. 10l oil but no coolant, stock dual mass, 110v alternator, ps pump, air con pump, cast exhaust manifold and downpipe, inlet, dizzy etc. Turned the scales on after the weight of the engine leveller had been taken up so it should be zeroed without it.



324.6kg man!



Jeez that's heavy. I'd had a figure for an AJ6 at 220kg and a Getrag 290 at 49kg so there must have been bits missing from those measurements. Either that or it was a 3.6 AJ6 with its lighter crank and no dual mass...plus some bits missing.

Bundled into the trailer I'd just re-boarded, ready for transport East to get shoehorned into a 60s Triumph...



With that out of the way, it could finally turn its wheels for the first time in maybe half a decade...



Well it drives!

Straight into the garage though as there were a few teething problems to sort



Bigger prop UJ fouling on the crossmember so that had to be clearanced, headlights not working (a bit of corrosion on the terminals...and helps if the earths are connected), washer pump seized and needed freeing off, wired up the oil pressure and coolant temp gauges the wrong way round, and forgot to do up the power steering cooler hoses so it pumped all the fluid out. Oh, and it's low man! Rolled the arches, but it's still catching on the arch liners on full lock. This is on a hill, but it's not a million miles off...




Took it for a quick spin around the block which highlighted a few more teething problems. Expectedly the tracking is horrendous, but also it won't really boost or rev above 3000rpm. It is on a base-map with an unknown hybrid turbo, so perhaps the mapper is keeping it safe until he can get it on a dyno. It's also loud. There's a killer drone around 2400rpm so will be making a little resonator J-pipe to try and cut that down a bit.

Oh, and there's a diesel leak from the tank. It's definitely the drain plug which I forgot to check before fitting the tank. I can just about snake an arm up to nip it up with a 17mm deep socket, but that hasn't quite sorted it. Ran out of time to try and nip it up again, but that needs sorting (especially with diesel at £2 a litre!).

So yeah. Plenty of teething problems, but none major. Big weekend!