1985 Jaguar XJ-S V12 HE

The fact that Jag decided to stick a refrigerant based fuel cooler on the return line doesn't help the apparent plumbers nightmare as that's plonked right on top of the engine. It's not immediately obvious what it is until a poke around the manuals either.

I need to get to know the engine bay a bit better. I think what puts quite a lot of people off is that there's quite a bit of stuff in this engine bay which you can't immediately see the purpose of. Some things are unnecessarily complicated...the cooling system for one still has me scratching my head...the routing is just *strange* in many ways. A couple of proper bleed valves wouldn't have gone amiss either.

I think the biggest headache with this engine bay though is just that (unless you're working on the throttle linkage) there is always something in the way. It's annoying compared to most classic cars (though rather familiar to those of us used to Citroens!), but honestly doesn't seem any worse than quite a few modern cars I've been unfortunate enough to work on.

It's awkward to work on. Some parts are expensive. It's horrific on fuel. The rear seat is more of a suggestion than anything else. Getting out of it if you've got a bad back is a nightmare. Have I mentioned it's horrific on fuel? Do I care? Not after the first time I drove it.

This really is a car which encourages you to go the long way to get places.

Like home to the charity shop over at Kiln Farm I check in on semi regularly as they usually have a good selection of vinyl that's mostly £0.50 apiece...a trip that's about four or five miles...but I ended up going via Buckingham, just because I could. Still didn't want to get out when I got there!

The windscreen washers have decided to pack in today. I'm guessing as with most cars of this age this is due to slime growing in the bottom of the washer bottle. It's easily accessible though so no problem. I'll pull it out tomorrow and give it a really good clean, then blow all the lines back through with compressed air. Sure it will be absolutely fine once that's done.

One modification I am definitely going to do is the deletion of the 15 minute "warm up timer" system. What this does is that if the coolant temperature is below 45C (measured by its own sensor to the rear of the right hand coolant manifold), for the first fifteen minutes it disables the vacuum advance system and retards the timing. This makes the engine less efficient, producing more heat and helping it heat up more quickly. It also means that for the first fifteen minutes it absolutely massacres your fuel economy. You'll be lucky to see the instantaneous MPG figure make it into double digits until this has timed out.

Given there is 5.3 litres of quite highly tuned V12 producing heat, it'll warm up in a perfectly reasonable amount of time, even though the engine weighs something ridiculous... there's really no need to deliberately make the thing use more petrol than it needs to!

Luckily this system can be disabled really simply by unplugging the appropriate temperature sensor. The associated hardware can also be removed to help improve space in what's possibly the most cluttered engine bay ever designed (I'm not sure designed is the right word..."happened" seems more accurate), though that's not strictly necessary.

Speaking of heating, the heater is something which needs help. Pretty certain that the tube has come adrift from the duct used to sample the cabin air temperature (or the thermistor value has drifted) as the only way to get any appreciable heat out of it is to set it to the demist mode. Bit of explanation needed here for those who have never used the heater in one of these. When it's set to anything other than demist the temperature is dialled in to a set value between 65 and 85F. There's no "as hot or cold as possible" setting. Which is fine and good when the system is correctly sampling the cabin...but a pain when it's not. The demist mode overrides this and just chucks out as much heat as possible, with the blowers set to maximum. It's also worth noting that there's no air distribution control like on most cars. So the only way to get air into the windscreen is to set it to demist...which puts the blower on full! I reckon that will be less of an issue once the air conditioning has been sorted as the cabin will then always be dehumidified...however it's currently a pain to keep it demisted - though the fact it's never stopped raining since I picked the car up hasn't probably helped. When it's set to demist you should get as much heat as possible, full power to both blower motors and air distribution set to 90% to the windscreen, 10% to the floor level vents. However the air coming out of the lower vents is never warm. So reckon there's an air distribution issue there. That's a job for another day though, I'm not pulling the dashboard apart yet.

Hard to believe I've done nearly 400 miles in it already! Wonder how many years of its previous life that would account for...

I seriously love these.... And the series one XJ's...

A neighbour, back when I still had my 66 mustang so must have been about 2003, had bought a series two XJ V12. Lovely thing, though the front was never as cool to me as a series one... Helped him on several occasions trouble shooting fuel pumps, running issues... Cramped as hell to work on, but such a cool thing to work on at the same time.

In dreams I sometimes trade my Granada for a series one XJ...In reality it'll probably never happen.

That would be really useful. The documentation I've come across so far doesn't really cover the ventilation system in much detail. So we've got vacuum actuators (knew the hot water valve was vacuum operated) *and* a load of servos...I can see no possible way this can go wrong...

-- -- --

450 miles in.

MPG on the last tank? Uuuuum...10.98MPG. Yeah, economy isn't her strong suit. That warmup timer needs to get in the sea and we'll see how much that helps. The trip computer is far more accurate than most modern ones seem to be. At least I can track it properly now... previously I was having issues there as I hadn't been able to get the tripometer to reset and the counter on the trip computer was getting wiped as I was disconnecting the battery overnight prior to sorting the stereo wiring issue.

Been busy most of today, so aside from briefly introducing a local friend to the Jag (yep, they were as surprised as I was to see it in my fleet!), I've not had a chance to do much with cars. Weather has been distinctly miserable anyway and not really conducive to working on cars.

However on departing the house to run one of many errands I was presented with this:



The way the lamp failure system works in the Jag is that if an appropriate amount of current flows through the lamp, a bimetallic switch in closes after 10-20 seconds after the respective lighting circuit is turned on to tell the system that the lamp is good, at which point the indicator on the dash goes out. If it doesn't detect this "lamp good" signal, the indicator stays lit.

In this case examination revealed that a number plate light was indeed out. Simply tapping the fitting restored it to operation though rather than the lamp needing replaced. So I'll add "clean number plate light contacts" to the to do list.

Good, because I could have done without standing in the pouring rain sorting that!

Have the service booklet in front of me just now and it looks like the standard service interval is 7500 miles or 6 months.

Some of the numbers involved are a bit ridiculous though.

Oil: 10.7 litres.
Automatic transmission: 9.1 litres.
Coolant: 19.5 litres (no, that is not a typo).

Made a quick run out of town today, partly for a change of scenery and partly as it's an excuse to drive on slightly nicer roads.

This has definitely improved my average fuel consumption from the previous 11mpg, but is still "far from frugal."



I think one of my jobs for this weekend will be getting stuck into the distributor and making sure the vacuum advance system is working properly. Apparently the old grease dries up and causes the system to lock up. The obvious consequences of this being an engine that's down on power and horrific fuel economy. The former is quite hard to detect given the abundance of torque available from this power unit!

This also has a huge impact on the exhaust gas temperature which really isn't great for the exhaust valves, which is something we want to rectify sooner than later I think given my reading seems to suggest that these engines dropping valve seats isn't unknown if the heads get unduly hot.

Now, to figure out how to get at the distributor without having to remove the cruise control assembly and half of the fuel injection system...

The "Hey, that's a lovely looking car...wait...that's *my* car!" reaction when walking back to it in car parks definitely has hasn't worn off yet.





Managed to get it a very quick blast over at the jet wash today (hoping to do it by hand at the weekend so mainly wanted to get the moss out of the window seals etc), get the impression this won't come up bad with a bit of work.



At least I've got rid of the huge greasy hand print I left on the bonnet a few days ago now.

Sounds daft but 13mpg I would consider good!

I managed to average just over 20mpg on a run to Subic, but after only a few weeks back in the city it was back to 8.

Who cares?

We, who also drive antique Toyotas, salute your commitment to Jaguars finest

OVIMOR

Would the distributor's likely advance/retard issue show up with a timing light? Or would you need to see what happens with the engine under load, not just revving it up and down with the car stationary and in Park? Obviously, no harm in pulling it apart and giving it some TLC, other than maybe disturbing surrounding items, but the potential for burned /dropped valve seems the bigger worry than economy. Best of luck, John

If you bung a timing light on it , and hold it at ,say, 2500 rpm steady , you should have a certain number of advance degrees , lets say 40 degrees .

if you then pull off the vacuum advance pipe it should go down by around 10 to 15 degrees . if there is no easily accessable pipe , then holding it at the 2500 , and then blipping the throttle wide open v quickly , should show the timing retarding momentarily as the vacuum reduces .

Apologies if you already know all this


regards
robert

Finally had an opportunity to give the Jag a proper wash today.







Which gave me the chance to give the bodywork a bit of a better appraisal.

The rear arches definitely need some attention sooner rather than later. Probably not a massive job to sort now, but give it a few years and it will be far harder.

Not quite sure what's going on with the number plate lights. Looks like the lenses have sort of disintegrated (and half painted over during the respray).



There are a couple of wide washers on the original screws which are sort of wedging the lens half in place. Methinks replacing these will be on the cards. Though they're £25 apiece so might not be particularly high on the list just now.

Spotted something which I'll need to attend to at some point shortly. Looks like the seals under the feed hoses to the brake master cylinder need changed.



I'll make sure it's not the hose weeping first though.

While the car was actually clean for ten seconds I decided to grab a couple of better photos.





















Figured that the next thing it would be sensible to do would be to throw some wax on to protect the paint until I have time to fully polish it. This it turned out was a mistake. I didn't spot the words "new and improved formula" on the bottle of aqua wax until after I'd sprayed half the car with it. Being new and apparently improved of course translates to "no longer behaves as I expect it to." As such I then spent nearly two hours trying to buff it off, without seeming to get anywhere.

Tomorrow I'll set about polishing and waxing it properly if the weather plays ball.

Planning to get into the distributor in the week when I should have a couple of afternoons with a decent chunk of time without interruption. Don't want to do that tomorrow as there's too much chance of me getting dragged off for other tasks and it's a job I'd rather get done in one shot rather than having to down tools and come back having forgotten half of what I'm doing.

Last little job I had a look at before tidying up was to see if the foggy reversing light lenses would clean up. It's a small detail but their being milky, dull and yellowed is quite obvious when looking at the rear of the car.

Before:



After:



That scrubbed up nicely, could probably do with a second pass (and the polish residue cleaning out of the lettering), but looks far better. I'll probably do all of the tail light lenses as even though they're not as bad as the reversing light ones they're all quite dull.

Speaking of tail lights, I do wonder how much of the US spec running lights is present in the cluster...I believe over there the little retro reflector in the side facing part of the indicator would have had a little 5W lamp behind it.

Sorry, I will stop spamming the thread with photos of this car eventually...