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

[myglaren]

I had a walk around today and saw many cars, mainly disappointing dowdy lumps, and thought of your nice sleek XJ-S.
The only car I liked was an older Jag, one of the nice wide ones, didn't get the model, too far away.

This sort of thing -

nicked from Bloomberg.

Don't like the new ones much.

[xantia_v6]

I would advise to get a better idea of where the oil is actually leaking from before tackling the oil filter assembly, as there are several gasketss and seals which could be involved, or it could be coming from above (camshaft oil feed or more likely, the half-moon seal on the end of the camshaft cover).

Note that the oil cooler on these is plumbed into the oil pressure bypass circuit, so the output of the cooler dumps directly into the sump and there are no significant pressures involved.

Even with the car on a hoist, reassembly of this is a bit tricky access seems to be worse than it looks, but thankfully much easier than the same job on the V12 e-type.

[Zelandeth]

It's tricky to really see where oil is coming from on this thing just down to the sheer amount of "stuff" that's always in the way. Plus it's a 35 year old Jag, so pretty much every area involving an oil seal looks a bit damp. I did look at the rear of the camshaft cover (the half moon seals are a classic leak spot on Saabs too), and while the area is definitely wet, it didn't look wet enough at a glance to be responsible for this leak...though looking back at the photos I'm now less convinced. I'll take a closer look immediately after an actual drive this afternoon and see if things look any more definitive.

Shame to hear the oil filter assembly is a pain to reassemble...it looks deceptively easy by V12 Jag standards at a glance! I'm guessing the inflexibility of the oil cooler lines attached to the assembly which bolts to the engine is the factor which makes things difficult.

[xantia_v6]

It is more than 20 years since I did that job on an XJ-s, but I recall the difficulties were that there is nowhere to swing a spanner on the oil cooler lines, and the vertical pipe that drains the oil down to the sump means that there is are two perpendicular (and mostly invisible) faces that have to be assembled in an oil-tight fashion. I was just a bit worried that your photo does not really show a smoking gun.

Maybe you need to get an endoscope camera.

[white exec]

Wonder whether, given the number of not very rapidly leaky bits, it would be worthwhile getting the underside steam-cleaned. This is done by outfits that MoT commercial vehicles, and wasn't expensive.
You could then monitor new/active leaks, amid all the rest.
Also a good precursor to underbody waxing.

The dash woodwork looking positively sumptuous

[xantia_v6]

My advice would be to start at the top and replace the cam cover gaskets (with the later sandwich gaskets from the 6.0), replace the half-moon seals, dowty washers on the cam feed banjos, and work down from there.

[Zelandeth]

I think a (careful) with degreaser and the pressure washer will be in order anyway.

Seems me and Xantia_v6 are thinking along the same lines. I know the top end leaks currently anyway...so it's going to want doing at some point...no reason not to do it sooner than later. Well aside from the job looking somewhat intimidating at a glance anyway. I'm assuming it's an inlet manifold off job as I can't see any way you'd get at things with the manifolds in place... probably a good time to get a fresh set of plugs fitted too if I've got to take half the car apart anyway!

Only a quick update today. I discovered yesterday that half the interior lights weren't working in the Jag. This happening immediately after I changed one of the switches involved seemed far too much of a coincidence, so I took a closer look. Sure enough, they're different. The new switch only be four pins on the back rather than six on the old one. So I switched over the cap from the old and new switches and put everything back together. Problem solved.

I've also painted the area behind the switches alongside the trip computer black for now. I will be looking for some veneer offcuts to rebuild the wood trim here in due course, but this looks better than the cracked, warped mess that was there for the time being.





The distributor breather air filter has also been swapped for something a little more standard looking.



The red anodised thing would have looked at home on my Suzuki Cappuccino...not so much on a Jag.

[xantia_v6]

Manifolds off to do the cam covers, nothing tricky there... Think about replacing the injector hoses while you are there, a fiddly job, but they do perish and you don't really want petrol spraying over the distributor cap and spark plugs.

BTW, one of the quirks of these engines is that they were designed with american threads (UNF, UNC) and fasteners, but in 1983 BL management decreed that all designs had to be converted to metric fasteners, but that project stalled. Your 1985 engine will have an imperial block and metric heads, so any bolt or stud that screws into the block will be imperial, and anything that is fastened to the heads will be metric.

Also change the cam cover screws for something with a proper thread, stainless cap screws look good.

[Zelandeth]

Oh, that's right...the cam covers have those strange self tapping things don't they?

Is it really shallow that I'm tempted to sand the surface of the grooves on the timing covers to show the stripes? Just seems the sort of detail which would look at home in the engine bay.

The fuel hoses are already on my radar...especially given that it's impossible to avoid ethanol blended fuel nowadays.

Is it possible to separate them from the connections to the fuel rail/injector to allow the hose itself to be changed, or does it need to be replaced as a unit? We're five minutes away from a hydraulics specialist so hopefully they will be able to provide me with everything I need. A1 Marine grade hose will be used to ensure it's essentially indestructible and engine bay fuel leaks shouldn't be a worry.

I'm hoping that a few jobs like this done will make the engine bay seem a little less daunting. Aside from some slightly bizarre decisions in the air conditioning department, there's nothing in the engine bay which is really unusual just there's a lot of large engine in there and there are two of a lot of things.

Have the oil and filter in stock now, so will get that changed shortly too. Wouldn't be the first time I've done that on a car and had an oil leak disappear of its own accord...though that's wishful thinking I think!

[xantia_v6]

Yes you can respray the cam covers and then sand them back to expose the stripes. On my e-type I painted them red.

The fuel hoses need to be cut off the injectors and rail, taking great care not to nick the fir trees. You need to use the correct size of injector hose (an odd size I think), available from good automotive suppliers. Take care to get the lengths correct so that the rail sits in the correct place.

On the A/C I can't remember if that joint is a flare fitting, or one with an O-ring. Be careful to support the fitting at the evaporator, on one of my XJ-S a professional fitter did not have the correct size spanner and managed to break the evaporator while fitting a hew hose.

Redoing to top end ancillaries on the V12 is a great way to familiarise yourself, and is very satisfying to see everything clean afterwards.

[Zelandeth]

This afternoon involved a lot of standing around and waiting.



It takes a while to drain off this much oil. To put in perspective how much oil this car takes...this much.



Not quite the 40 odd litres a Detroit 8V71 takes, but a lot for a car!

What came out wasn't disgusting but equally it was definitely due a change. The fact that I had to resort to "mechanical assistance" to remove the oil filler cap and the battle it was to shift the oil filter tells me it's been a while since she had an oil change. I'm equally aware that she's had a miss for quite a while before I got her so there's probably some degree of fuel contamination in there.

It's not the most inaccessible oil filter I've ever come across, but it's definitely close. Nothing from above. The circular thing you can just see through this gap is the oil filter housing.



From underneath is nearly good...except for the fact that the left hand exhaust downpipe runs directly under the filter so gets in the way of you being able to get a hand onto it. A not insignificant amount of swearing was involved, especially as the filter was thoroughly stuck in place. At least it's mounted vertically so you can fill the new filter with oil to help prime it and minimise the work needed to get oil pressure back up.

While I was waiting for the oil to drain down it gave me a good opportunity to double check the rest of my fluids etc. Especially the coolant. Glad to report that it's not moved at all since it was originally topped up.



The cap was horribly graunchy to remove or loosen, so have given it a tiny smear of rubber grease on the seal. Lovely and smooth now.

It was about that point at which I noticed some bodgery which will need to be resolved before I get the air conditioning reinstated. Generally it's one of those areas where you see nice big, chunky hermetically sealed fittings. Jubilee clips aren't normally on that list. Especially on the hot gas line to the condenser...





Yeah...that will need to be replaced. At least the hose isn't expensive. One found for £35 delivered over here on British Parts, which makes me wonder all the more why they messed around with this. Have to wonder how long it has worked like that as the hose clips and everything don't look recent.

I spotted something about that point which I need to pick the brains of the Jag experts about. Not a problem, but a "why is that there?" type question. Why is there what appears to be a second ignition coil tucked down in front of the radiator?



It appears that the HT terminal is capped off, but it's definitely hooked into the loom so must be doing something. I'm curious.

Oh, on reading the handbook I discovered that the steering wheel has a reach adjustment. Turning the knurled collar releases it and allows about 3" of adjustment. Doesn't sound like much but really makes a difference.



I'd never have found that by myself!

While looking at the interior I figured it was worth snapping a photo of the switch panel in black with actual daylight involved.



It's actually growing on me...the veneer there almost clashes with the black of the trip computer casing and this whole panel being black looks a bit more coherent. Obviously it wants to be painted properly as it's a bit rough and ready at the moment so the finish isn't great as it was only intended as a stopgap. That's easily fixed though.

We did have a fun moment in the afternoon when attending a hospital appointment. What odds would you have given two V12 engined cars ended up parked next to each other in the hospital car park completely randomly?



Think mine sounds better...

[xantia_v6]

A few point to cover here...

Firstly, you don't check the coolant level at the cap on the engine (which should be a fully sealed cap (no pressure releif) or a 16 psi cap. You should check the level at the other cap (13 psi) on the header tank on the LH wing behind the radiator (and not the catch tank which is mounted inside the wing behind the front wheel). The fact that the level is OK at the engine cap is a sign that the bleed valve is working (they are often gummed up).

The bodge on the A/C hose is strange, but not in the way that you think... That is actually how all the 5.3 litre cars left the factory. It is a unique jubilee clip with a distance piece so that it is fitted the correct length down the hose. If you buy a replacement hose, it will have no fitting on the end. I did have to replace that hose on mine last year, (it was the original from 1975), but the hose actually blew off the crimped fitting at the other end, the jubilee clip was still holding fine. The A/C shop insisted on brazing a modern O-ring fitting on to the compressor manifold and making up a custom hose to suit.

Getting sufficient ignition dwell angle on multi-cylinder engines has always been a problem. The first widely used system was the dual-point setup on the Ford flathead V8s from 1932. When the Jag V12 was put into production, it was the first application of the lucas OPUS electronic system which has about 95% dwell and had a special low inductance coil to cope with the demands of supplying over 650 sparks per second. The OPUS was never very reliable, and the HE engine required even more spark power due to the higher compression so Lucas cobbled together a system based on the GM HEI ignition. Lucas could not however make a coil that could charge quickly enough, so the solution was to add a large inductor in parallel with the ignition coil to store more energy which then transfers into the coil as the spark occurs. The "coil" you see in front of the radiator is the extra inductor. In 1989, the Lucas ignition was ditched and replaced with a Magneti-Marelli system with electronic timing control. The Marelli system overcame the coil charge time problem by having 2 coils with separate HT distribution for each bank (which created a new set of problems we will ignore here). The Marelli system had a coil with lower inductance, and someone at Jaguar worked out (or maybe guessed?) that the Marelli coil could be used as a substitute for the Lucas coils on the earlier Lucas HEI system and from that point Lucas discontinued supplying the original spare coils (which were unique to this engine), and the Marelli coil was fitted instead, but it was important that the extra coil inforn of the radiator is disconnected in that case. My 1985 car had had a Marelli coil fitted and the wires to the front coil had been cut.

[white exec]

JOOI, Mike, on the V12, do any cylinders spark/deliver power simultaneously? I was intrigued by your figure of 650 sparks per second, which is quite a delivery rate.

When I ran a Rover V8, there was always an issue not so much with dwell, but with wear on the heel of the contact breaker (even when oil-pad lubricated), which caused dwell/timing to wander and points gap to gradually lessen. After being set, the gap normally needed resetting again after as little as 2-3k miles. Pain.

Solution was to fit breakerless to the distributor, either optical (Lumenition) or Hall-effect, and couple this with a capacitive discharge high-frequency d.c. unit, which drove a standard coil. A company called Electronize marketed a kit (and ready-built units) which provided this. It retained points, but reduced the current through them from the original 3-5amps to around 50mA. This stopped points arcing, but still left the problem of heel wear. The Electronize unit also fed the primary of the coil with high-frequency d.c. pulses, at around 300v instead of 12. This h.f. drive made the coil work far more efficiently, but within its insulation spec. The result was a powerful spark (around 8mm if sparked to Gnd, iirc) of longer and controlled duration. This greatly improved starting.

I went a step further with the Electronize unit, and ditched the mechanical points. Fitted instead a Hall-effect sensor, one from RS (in a V3 microswitch package), and mounted in place of the points, with a 8-slug inductor ring fitted to the cam. Without the mechanical points, idle and high-rev running both improved noticeably, and timing/dwell drift vanished. The system stayed on the car for years, and around 100k miles.

[xantia_v6]

6500 RPM x 6 sparks per revolution (4 stroke) / 60 seconds gives 650 sparks per second I think. Many CDI systems would also struggle to recharge fast enough.
There are other good reasons that CDI was never generally adopted including (relevant for the V12 HE) that the CDI spark pulse is too short (duration) and leads to intermittent poor combustion and increased emissions.

All of the ignition systems used on the Jaguar V12s had adequate performance, but the OPUS suffered from frequent failures due to inadequate component ratings and the placement of the electronic box on top of the engine block where the temperature often got to 130°C with practically no ventilation because the A/C compressor completely shields the cooling fins. Lucas finally produced a modification kit to relocate the box, but only after all the cars fitted with the system were already out of production (fortunately mine has had the modification kit fitted).

The Lucas HEI system fitted to Zel's car has adequate performance and is very reliable, but only has inaccurate mechanical and vacuum advance systems, wheras the V12 HE engine needs tight control of the ignition timing to get reliable peak performance and economy.

The later Marelli ignition has adequate performance and computerised timing control, but has an archilles heel in the HT distribution which effectively has 2 separate 6 cylinder HT distributors concentrically located in the same cap with a double-ended rotor, each end of the rotor feeding 6 cylinders from a separate HT slip ring connected to a coil. These rather fancy (and expensive) rotors often fail, and for cars fitted with catalytic converters often cause serious engine and car fires.

There were also 2 other ignition systems fitted to the V12 (Zytec and PECUS), but they are quite specialised and rare.

[white exec]

Really interesting detail. Can see the attraction of separate HT modules for each spark plug, so doing away with mechanical distrubutor and the dwell/duration problem.

Interesting comparison with Rover V8, where there was so much torque available at low/mid revs that high-rev ign issues were not a problem, except for racing engines (eg a tweaked Vitesse, by which time EFi had happened). For normal carb'd road-going V8s, typical to see 27-29mph/1000rpm, so not a lot of point in exceeding 3000rpm. Jag V12 in a different category, of course.

Remember there being an issue with the P6B V8 where the ammeter (!) used to show something of a discharge when driving gently at moderate revs. Lucas/Rover (god bless them) had overestimated engine revs at low speeds, and fitted too large a pulley to the alternator! Lucas depots got a memo about this, it seems, and would fit a smaller diameter pulley to the alternator f.o.c. Problem sorted. With 400W of main beam fitted by some of us, this sort of thing mattered.