Zel's Fleet Blog - BX, Jag XJ-S, Sinclair C5, Mercedes 208D & 230TE, AC Model 70.

[xantia_v6]

The xjs jacking points are on the floor panel, not the sills, but that makes them perhaps more susceptible to rust damage.

I know that the floor panels on mine are ok, as I had them replaced, but in case of doubt, the front subframe is the best place to jack.

At the rear, the jacking points are next to the trailing arm mount, and difficult to get a jack squarely on them. You can safely jack the trailing arm mount (if it has not turned to Swiss cheese), but safest is under the diff. It is a good idea to cut a block of wood to spread the load on the panel under the diff.

If lifting the rear other than under the diff, watch that the subframe mounting rubbers are not letting go, or you could find the rear subframe unexpectedly on the floor.

[Zelandeth]

The xjs jacking points are on the floor panel, not the sills, but that makes them perhaps more susceptible to rust damage.

I know that the floor panels on mine are ok, as I had them replaced, but in case of doubt, the front subframe is the best place to jack.

Cheers for that. I thought it was the subframe I'd used but just couldn't remember.

Will only be the front they'll be jacking up so hopefully the rear subframe will remain attached to the car! Would probably expect them to lift the rear from the diff anyway as it would probably be the quickest way for them to get both sides up.

Have to admit to being really curious to see how much difference and in what ways having a not utterly destroyed set of tyres on the front makes to how the car drives. Hopefully it will give me something like a chance of diagnosing any other front end suspension/steering issues...with them being unevenly worn from the tracking obviously being miles off for years, plastic and badly out of round it's just impossible to tell at the moment what's tyre and what's suspension.

[Zelandeth]

So our starting point today...



With enough of the interior reassembled as to make the car reasonably drivable we went off to collect the tyres. Via an Esso fuel station to sample their Supreme+ super unleaded which I learned in the last week or two is in fact still ethanol free (despite the E5 label on the pump - an E0 label simply doesn't exist according to their website), so I'll be using that for the forseeable future. The very first thing I noticed though was that it actually smells like what I remember fuel smelling like back when I started driving, rather than the more gas-like smell it's taken on since the early 00s.

We go to the nominated fitting garage at the agreed time and they did indeed have my tyres...they absolutely couldn't fit me in to get them fitted today though. I'd had enough by that point though, and given my unease with using a garage I didn't know and not being allowed anywhere near my car while it was being worked on I just said "thanks" and stuffed the tyres in the passenger seat and headed for Formula 1 in Newport Pagnell to get them fitted.

Yep, I was right that my high speed evasive action before I'd been able to deploy cadence braking had resulted in a "slight flat spot" on the ancient, already knackered front tyres.



That's quite plainly why the car wasn't driven again after that incident.

While the wheels were off I took the opportunity to take a look at the brakes...as F1 were absolutely fine with me using the time to look over the bits of the car that I wouldn't normally see without removing stuff.





Pads don't have a huge amount of meat left on them but they're getting swapped out with the warped discs shortly anyway so I'm really not bothered about that. Nice to see the pipes all look in decent order though. Hoses are nice and supple with no perishing apparent.

Doesn't this look better!





As I hadn't reassembled enough of the dash to have refitted the dash lighting rheostat I just headed directly home from the garage as I was critically lacking any dash lighting. However on the couple of miles it's fair to say that it's a huge understatement to call the car transformed. I was somewhat worried about front end alignment issues as the car has always pulled quite strongly to the left, even after I'd had the tracking done. It was about 8 degrees off when I got the car, which was probably why it wandered all over the road and had wrecked the tyres! It now tracks near as makes no odds absolutely perfectly straight. Think it pulls very slightly to the right on braking...but I'll worry about that if it's still an issue after the new discs and pads are in and I've cleaned up the brake pad slides. It's only very slight anyway. The horrendous vibration anywhere north of 50mph has completely gone, though there's still a very slight vibration through the car at exactly an indicated 70...1mph higher or lower and it vanishes. It's not through the steering wheel though so I'm suspecting rear wheel balance, especially as I'm pretty sure that the nearside rear has thrown a weight based on a witness mark on the rim. It's very slight though so not something I'd consider worrying about...being so slight could be almost anything in the driveline that's to blame as well.

The ride is vastly improved as well (unsurprisingly), the front end being nowhere near as crashy as it used to be. Noise levels seem reduced as well, though it's a bit hard to judge that as I've had to keep the windows open due to currently lacking half a ventilation system...and the exhaust isn't exactly quiet.

I need to make a couple of essential journeys tomorrow so if it's dry I'll try to get her out for a proper run to get a better feel for how the car is now behaving. Need to get her booked in for an MOT soonish too...Willing to take the car in now, I couldn't have shown my face in the testing station with those tyres in that shape though! Nor was I willing to drive it in that state - hence the car having been parked up for a while until I decided to go down the cheaper route to tide things over until we're in a better position to pick up the properly specification correct 215/70 R15 W tyres.

[CitroJim]

Excellent

Zel, I cannot forgive you for not calling in and saying hello especially as you were less than a quarter of a mile away from me whilst having those lovely new tyres fitted...

Don't let it happen again

Good old Formula 1 You can always rely on them to see you OK... I guess you'll not be dealing with the other mob again...

[xantia_v6]

The new tyres should transform the handling and ride. You may want to play with the tyre pressure a little, especially as the tyres are a slightly different size than the original.

re the front brakes, it is quite likely that you have a sticky piston. The original pistons are chrome plated steel, and if the fluid has not been changed regularly, they suffer from rust pitting and don't move freely.

On these calipers, the seals are mounted in the calipers and the pistons slide inside the seals, so the pistons are fairly cheap to sleeve or replace with stainless versions. I just mention this because replacing the pistons and seals is probably cheaper than replacing the calipers, which might be your first thought.

Also, in case you had not noticed, you need to remove the calipers from the hub carriers and hubs from the stub axles to change the disks.

[Zelandeth]

It really has transformed the car. There's definitely still a bit of a vibration from the back somewhere. First thing I'll probably do is drop back by F1 and get the rear wheels balanced (and check while on the machine that neither of the wheels/tyres is out of round) as it's a cheap, low effort thing I'd like to get done anyway. I'm pretty sure one of them has thrown a weight at some point as there's a suspiciously clean rectangle which has clearly had a balance weight on in the relatively recent past. Given what a sloppy job was done of fitting the weights it wouldn't surprise me if the fitter never cleaned the rim properly before sticking it down.

I remember you mentioning the procedure a while ago for disc swapping I think. As I recall it's caliper off (which I note the bolts for are lacking the lockwire which should be fitted - have bought the tool needed to fit that), hub off (just a big nut on the stub axle I assume?), then with the hub off undo the five bolts holding the two together - I can see that being a job for which either a sturdy vice and/or impact gun are going to be needed - then reassembly being the reverse of removal. Actually refitting the lockwire this time that the previous repairer apparently didn't.

Since I've put a little more air in the tyres the car seems to be pulling up in a perfectly straight line, with any apparent brake imbalance having vanished. So I'm guessing it was down the the pressures being a little mismatched rather than a braking issue, assuming it's not an intermittently sticky piston anyway.

[Zelandeth]

Back to battling with the world's most overcomplicated HVAC system in the world's most overcrowded cabin.

While I know the system has some issues, I'm reluctant to go doing stuff like pulling blowers and the whole system to bits until I've seen how it behaves with air actually going through the heater box rather than just all bleeding out behind the driver's side trim panels. It's obviously kind of hard to tell how the system is behaving when 50% of its air supply isn't connected properly. I'd ascertained that most of the fundamental bits of the system were at least somewhat functional.

Before I could really tell much however I had to get our old friend, the plenum back in place. This thing.



After having made four attempts so far at getting this thing back in place (which looks deceptively simple) I'd pretty much come to the conclusion that I basically wasn't going to get it back in place without further work. The most obvious solution was to remove the blower motor, attach the plenum to that then wrestle the whole lot back into place as one. This would be easier if Jaguar hadn't in a typically Jaguar fashion attached half a dozen other things to the blower motor frame because it happened to be a flat(ish) surface.

Exhibit A: The right hand blower motor and (almost) everything attached to it.



This wouldn't be quite so much of a headache if all of the fasteners were easy to get at, and if someone hadn't already stripped the heads of two of the screws out. I'd really rather not have to take that out if I don't have to as the moment you start getting involved with stripped screw heads you know you're likely in for a world of pain.

This was the point at which I basically had a critical patience failure with the plenum. At the end of the day it's just a glorified rubber hose, just one end of where it attaches to is horribly awkward to get at. So I set about mutilating the plenum. Plan 1 was to cut one slit in the base of it. This would allow me to get my hand inside the thing to assist in wrangling it into place.



This improved my available dexterity by about 300% and more importantly allowed me to be able to feel when each corner was actually positioned properly. Sadly this still wasn't successful as it's such a tight fit on the blower. I kept getting three corners on, but the opposite one would always pop off every time I tried to get the last edge on. So I hacked the thing actually in two and made up a sleeve to rejoin them together.

Getting the "stub" onto the blower still took me a good twenty or thirty minutes because it is a ridiculously snug fit. There's no chance I was ever going to get that into place without either having made the plenum easier to handle or removing the blower. Once that was in it only took a few minutes to get the now separate lower section in, and five minutes to (using an adaptor collar from a generic cone air filter) join the two together. It ain't pretty! I'll be going back in tomorrow to cover the ally tape with duct tape tomorrow just to give it a bit more structural support...not that this thing can really go anywhere. There's a really snugly fitted collar between the two sections of pipe so it's not going anywhere...absolute bonus is that it doesn't seem to be leaking either. The duct tape will add an additional barrier against any electrical shorts given the proximity to the various bits of loom. I like using this ally tape though on any work like this because while it doesn't have much strength it does tend to produce a very good seal. It's also very flexible so tends to form a really good seal even on oddly shaped or uneven surfaces. It does need some protection over the top of it though.

Less said about this the better I think...but it's not leaking and it's buried behind a trim panel...so I'll take ease of service access.



Turning the heater controls to demist, a huge collection of detritus was ejected from the windscreen demisters and centre vents (not been decent airflow for a few years then!) and almost immediately I had nice toasty air out of the vents. It's the first time I've ever actually felt any appreciable heat in the car...before "luke warm" is about the best I've ever had. I still think it's thinking the air sampled from in the car is warmer than it actually is as with it in normal heat mode it drops out after a few minutes - opening the doors though did get heat back on, and switching between demist and cooling shows that the actual hot/cold mixing side of things is working fine. Oh, we do actually have appreciable airflow through the centre vent now too. Not exactly hurricane force, but an order of magnitude better than it was.

So it seems the complete lack of heating performance was at least largely due to there simply being so little airflow actually through the heater matrix, as it was mostly exiting straight out of the right hand side of the heater box and bleeding out around the trim in the footwell.

I was going to take a test run to see if it would keep behaving itself once we were on the move...right up to the point at which I realised that I was lacking in functional windscreen wipers.

Bearing in mind that it had started pouring with rain about halfway through this work (in contrast to the forecast!) I decided that this was something to have a look at tomorrow. Hopefully I've just jostled the fusebox while I was messing around in the footwell.

I want to have a go through the fuse boxes anyway as it seems that there's been a completely random approach taken to fuse replacement in this car over the years. This for example should be a 5A.



Hmm.

In addition, this dropped out the left hand fuse box when I pulled the cover off. This sort of thing instils confidence doesn't it!



Hoping that was a "get me home, my headlights have failed" type fix. It wasn't fitted, just rattling around behind the lid (no doubt just waiting to short things out)...I do note there's one dodgy contact in that fuse box too, so may look into replacing it. At least it's a small fuse box.



Note another incorrect fuse there...another 17A on the far left where it should be 10A.

Let's just hope this doesn't wind up opening up a new can of worms!

[Hell Razor5543]

The problem with opening a can of worms is that you almost always need a larger can to put them back in (as they won't all fit back in the original can)!

[CitroJim]

The problem with opening a can of worms is that you almost always need a larger can to put them back in (as they won't all fit back in the original can)!

That's very true James Well observed

Zel, excellent The de-snagging is coming along a treat...

The XJ-S designer must have been French, surely?

It's got French stamped all over it

[Zelandeth]

The problem with opening a can of worms is that you almost always need a larger can to put them back in (as they won't all fit back in the original can)!

That's very true James Well observed

Zel, excellent The de-snagging is coming along a treat...

The XJ-S designer must have been French, surely?

It's got French stamped all over it

I think saying "designed" might be going too far for a lot of the vehicle systems..."Happened" I think fits better.

No one thing is actually too bad...it's just that nobody actually seems to have ever really sat down and put any thought into how these things will fit together and whether any provision for service access might be needed.

Okay...the HVAC system is a bit French. The whole control scheme being electronic over electromechanical over vacuum still makes me scratch my head a bit. When you've already got an electronic to electromechanical interface going on, why not just use solenoids and/or servos to operate stuff? Why add another entire level of complexity by adding a vacuum system? The term "a solution looking for a problem" springs to mind.

The servo unit is something else though, really looks like something you'd expect to find in some piece of industrial equipment rather than an automotive ventilation system.

[CitroJim]

Why add another entire level of complexity by adding a vacuum system? The term "a solution looking for a problem" springs to mind.

Yep, that'll be it and because they could

But seriously, there must have been a reason as car makers aren't known for going on expensive flights of fancy if it's not strictly necessary? If they can save a penny here and there, even on a prestige car then they will...

Sounds like rather than saving pennies, they spent rather a lot of them...

[myglaren]

The reputation of the British in Sweden was that we find very complex solutions to very simple problems.
Jaguar seem to have taken that on board and excelled with it.

For a marque with quality as a major part of its reputation they seem quite adept at shooting themselves in the foot.
One of my boss' had one, not sure of the model but new in 1980, it had a huge hole in the carpet.
He did say that "Jaguar is a ritzy motor but no better than a Ford"
Disheartening words.

[RichardW]

Bit like the space race and writing in zero gravity... The US spent millions developing a pen that would write in space. The Russians took a pencil.

[Zelandeth]

Bit like the space race and writing in zero gravity... The US spent millions developing a pen that would write in space. The Russians took a pencil.

Which granted did bring its own challenges. Microscopic graphite particles floating around inside a spacecraft in zero G isn't exactly a good thing...

This is the single part of the Jaguar system which makes me go "Seriously...just WHY?!?" I give you the "servo unit" as used on the XJ-S.

These images are from a now defunct eBay listing.

That is controlled by an electronic unit...this thing (while a bit of an engineering marvel in itself...just seems an unnecessary layer when you've already got electronic control.

[mickthemaverick]

I can only assume that the use of the vacuum servo is as an amplifier of sorts. The electronics probably cannot carry sufficient current to operate heavy loaded servos so they use the low current to control electromagnetically operated valves which control the much stronger vacuum system to provide sufficient umpf to power the flaps and water valves in the system. I'm fairly convinced they didn't do it simply because they could!!