1985 Jaguar XJ-S V12 HE

Car port sadly is a non starter here due to planning rules, and there is already blistering in quite a few places from it having spent a long while under a cover in the past. It will be waxed to within an inch of its life though...

First task for today was having a look at the throttle balance.

The throttle actuation rods were waaaay out of whack, meaning that the throttle pulley was resting a good 1/2" off the closed throttle stop. This was due to the left one. The right one is currently seized in its bushing but has been left soaking in Plusgas so I'll give it another poke in the future, it was in about the right place at least. At least with my foot off the throttle the throttle position sensor will be seeing that the throttle is actually closed now.

When I checked everything at rest after that was adjusted, we had 4% CO on the left bank and 0.5% CO on the right.

After adjusting the stop screws I was able to get things stable at 1% on the right and 1.2% on the left. I was kind of hoping I could aim for 1.5% (smack in the middle of the 1-2% quoted in the handbook), but I couldn't open the driver's side up any further without opening the throttle itself because I couldn't adjust the actuating rod on that side.

Right:



Left:


It's a lot closer to correct than it was. The car smelled very obviously rich before, it doesn't now so it seems I've done something right. Idle is very obviously smoother too.

Next up was some detective work to figure out why the lighting in the stereo was refusing to go out.

Pulling it out of the dash revealed clear evidence that someone has been in here before.



Have to wonder if this was more recently when the speakers were changed or if it was back when the head unit was replaced back in 1988.



Helpfully the handbook for the head unit contains a clear wiring diagram which made the detective work a lot easier.



Didn't take more than a couple of minutes to track down that someone had connected what should be the permanent live for the memory backup to the line which should be connected to the dash lighting circuit. That will be why it was always lit up then. Goodness only knows how long it's been like that.

At first I couldn't actually find the wire for this, but after groping around blindly for several minutes I found this.



...Which when tested turned out to have 12V present on it when the headlights were turned on. That will be the illumination feed then.

Having connected this to the appropriate terminal, tested it and stuffed it back into the dash it initially didn't work. Well it did but I couldn't receive anything because the terminal for the power antenna had been pulled out. Second time round, having more carefully routed the wiring bundle we had better luck.

Headlights off:



Headlights on:



It's hard to tell from the photo, but the display is dimmed when the lights are on. Sadly the bulbs which should provide lighting to the buttons on the stereo have burned out, so I'll need to conduct some microsurgery to sort that at some point in the future. For now though it has solved the problem with it refusing to switch fully off. Do wonder how long this has been causing issues with battery drain...

The four screws which were meant to secure the cage for the head unit to the dash were also missing...so someone didn't take much care when they were in here last.

Feels like a reasonably productive afternoon.

Good work!

Balancing the throttles on these can be a pain as not only is there an Auxiliary Air Valve on the left bank to control idle air and extra air to a cold engine; there's a stinking huge balance pipe at the back connecting both intake manifolds. When the AAV starts to get weak with age (its only a wax capsule using coolant temperature to open/close a small piston), sometimes it can start to hunt when cold and people adjust the throttles open to compensate for it.

While I think about it, I'm pretty sure I've got an old XJS Clarion stereo in the shed - if its still there and you want it as donor guts for your unit, you can have it!

I'm assuming by now you'll have discovered the XJS bible..?

www.jag-lovers.org/xj-s/book/Jaguar.html

I remember the vac system to the distributor was very complicated with thermal switches which bleed vacuum off to change the timing as it warmed up, the only purpose I could see for all of this was to meet the emissions, I ran mine with dizzy directly to the manifold and it worked fine, no pinking and the mot emissions are measured hot anyway.

Re XJS bible, richw82 just beat me to it! This is a very good read and has been useful for my VERY protracted XJS rebuild. All the very best for keeping this car alive! Also - don't forget to check that dingbat system of a coolant expansion overflow tank behind the front left wheel arch - a built-in rust generator if there ever was one!

Also of use, and unfortunately I can't find the link any more, is the Browns Lane photos of the early XJS build so I'll upload them here for you and anyone else to reference.

Let's have a look at the non functional full throttle kickdown.

Having done a bit of research I discovered that the kickdown system is meant to be triggered by a microswitch on the throttle cable right next to the throttle cable tower.

The way it works is that when the throttle itself hits the stop at full travel, if you press the pedal further it then pulls the sheath of the cable back against a strong spring, which then acts against a microswitch.

This relies on the cable being pretty much perfectly adjusted to get sufficient travel to activate the switch...and sure enough mine wasn't even close. It's a quick and easy thing to adjust though (probably the only easy to access adjustment in the whole engine bay!), so was a quick matter to correct that.

Sadly it hasn't apparently resolved the issue, though I've yet to confirm the switch itself is working (they're apparently not particularly reliable) as the meter was making a bid for freedom the moment I let go of it because of the wind. I gave up when the bonnet blew shut on me for the second time.

If that switch is working, there's a deeper issue...but I'm not going to worry too much about it just now. It really doesn't affect the driveability of the car (the normal "mild" kickdown feature works fine, it's just the "kick in the pants" mode that is acting up). On a car with more mild power availability it might be more of a headache.

Something a bit less involved needing looked at is the state of the wood trim. It's the first thing people notice in the car.







The wood itself actually looks to be in good nick. It's just the lacquer layer that's peeling off - not unlike a Dante Red Citroen!

I've never dealt with anything like this but have a rough plan of attack in mind. The bit I'm expecting to be the biggest headache by far is physically detaching the bits of trim from the car so I can work on them.

Probably the trickiest bit with regards to the actual wood I reckon will be getting the remains of the old lacquer off. I'm not expecting it to just peel off nicely, and will probably have to get some paint stripper involved. I don't think sanding is an option as I reckon because it's patchy it would leave high and low spots...also I don't know how thick the veneer is and really don't want to risk rubbing through it.

Once I've got rid of the old manky lacquer it should be pretty simple I think. Quick coat of stain to give it some colour, a skim over with some really gentle sandpaper to key the surface, then a load of light coats of clear coat. I believe polyurethane varnish is normally used commercially...though part of me is wondering if normal automotive clear coat could be used? Both because it removes the requirement for brush painting (which I hate) and I have it in stock in the garage.

Open to suggestions from folks who actually know what they're doing there as this is a bit of a new challenge for me...is the first car I've had with actual wood trim for one thing!

I mentioned a couple of days ago that the lights in the boot which I had revived were pretty pathetic. Having a rummage through the box of "misc automotive bulbs" this morning I came across a couple of 5W LED festoon lamps which I'd stuffed in there a couple of years ago. They're a horrible 6000K bluish colour, which is why I had just stuffed them in the box and forgotten. However for a boot light I'm not so bothered about the colour temperature as it's purely practical.

With the first one in the difference in brightness is immediately obvious! The one on the left is barely even visible.



Reckon that will be a bit more useful when digging things out in the dead of night.



Hopefully the weather tomorrow will be slightly less ridiculous and I can get a couple more things done.

The brake judder should soon be sorted as a set of discs has been ordered. Was braced for eye watering prices but they weren't too bad, can't remember exactly what the number was, but I think the pair of discs and pads was around £100. Was bracing for several times that. Will be nice to get that done as it's really the only thing that's really obviously amiss from the driver's seat to be honest.

Love that v12 sound, gotta be wonderful just gliding along in it. Looks like you're really giving the car the love it needs too, which is nice to see. So many old Jags seem to get run into the ground, without people stopping to fix those small problems and do those basic service jobs (like balancing the throttle)



Regarding the wood, I'm far far far from an expert, but I'm just starting the same journey with my Daimler. From the picture you're put up, it looks like the veneer is in good condition and it's only the lacquer that's damaged, which makes your life easier. Check out petervdv thread for some ideas.

From what I've learnt so far, I would suggest paint stripper as opposed to sanding to remove the old lacquer. The veneer will be about 0.6mm thick, so very easy to sand through, especially at the edges. Having removed the dark lacquer from my dashboard it's revealing that a previous owner has already sanded though lots of my veneers, I think I will have to remove it all and start over, which is a little daunting!

After paint stripper you can use fine sand paper very carefully to just refresh the surface. If you wipe the now bare wood with a damp cloth you will be able to see the colours that will come through with a clear top coat and decide if you need any stain. The walnut burr is lovely colour and I believe wouldn't have been stained at the factory, just clear coated.

What clear coat to use is something that seems to be a hot topic, with many different answers. As I've not got to that stage myself I can't really comment, only suggest it's worth reading up as there seems to be pros and cons to the various finishes available.

So nearly 11 litres of oil and 12 spark plugs for a big service! Thems is good numbers.

Not something I've come across, the supplier I use still has stuff in 5 litre containers, though they are more of a trade outlet so probably have more variety. They also stock 25 litre drums, which I may well switch to given these quantities! I thought the van holding 7.5 litres was bad enough...



Let's not forget that the book time for changing all 12 plugs is 8 hours on account of having to remove the throttle linkages and A/C compressor to gain access.

Hehe, it's no wonder that so many ended up in scrapyards back in the day! I'll bet most garages and mechanics considered them to be a plumber's nightmare, and didn't want to touch them with a bargepole.