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

[Zelandeth]

Ah, the joys of Jaguar. Apparently the coolant checking procedure in the handbook is incorrect then as that's where I found which cap to look under. Note to self: Check it under the expansion tank cap...which did make more sense to me in the first place to be fair!

Interesting to read of the technicalities of all the different ignition systems.

I imagine the biggest downfall of coil-per-plug type systems (aside from the cost of 12 ignition coils!) would be reliability. I seem to recall the ignition coils on the XJ8 a friend had causing more issues when he had it than anything else on the car by a long shot...and that was on a 1998 car. We both reckoned that the ambient temperature was to blame...and that seems even worse on the V12 than the later V8. I don't personally recall these systems appearing on anything before the 1990s anyway.

The potential for disaster on cat equipped cars with the later ignition system does sound downright terrifying...definitely sounds like a situation where it's worth engineering a fail-safe system of some sort would be worthwhile.

Derp on my part regarding the pressures present in the various bits of the AC system...how long it is since I really worked on this stuff is showing! I imagine the decision regarding the hose clips was that the seal was good enough and that the system would get serviced every year or two anyway. Given the price of refrigerant these days though I think it makes sense to take reasonable steps to get the system as well sealed as possible. Given the hose can easily be rotated at the condenser end, the grip on the inner pipe appears to have failed over the years.

I've seen plenty of farmers who have bodged AC kit with hose clips...but this is a first for finding stuff having left the factory that way!

I wasn't 100% happy with the finish I had achieved on the glove box lid. It ended up looking a bit less smooth than I was really aiming for. So today I pulled the trim back off and gave it another few coats. Is now looking a lot better.







The helpful bit of workflow I added to the mix today was to set the heating running in the back of the van to a nice toasty 25C and use that as my drying room. That understandably sped things up a good deal and seems to have helped achieve a better finish.

[Zelandeth]

I believe there's a get together of car enthusiasts tomorrow morning. My intention at this point is to get along to it. In preparation for this I figured I'd at least blast the worst of the grime off the Jag.





Plus side of me having waxed it to within an inch of its life a couple of weeks back was that it scrubbed up pretty easy.

Still reckon this was one of the best bits of cleaning gear I bought in the last year.



50m hose which bundles up to fit in the washing bucket and is thus far 100% kink proof. Expensive for a hosepipe but the amount of aggravation it saves is well worth it I reckon. These expanding hoses are really strange but well clever.

[Zelandeth]

So despite the weather I decided to try to get to the breakfast meet up this morning.

Despite a not insignificant amount of debris on the road there I got there without incident. 1700kgs of very low car is a pretty good formula for "doesn't care about side winds."

I wasn't the only one mad enough to be there either!























This was the point that I got the call telling me that the roof was about to blow off the shed, so I had to leg it back to base.

Despite the legendary hate that all British cars are apparently meant to have for rain, the Jag handled getting well.and truly drowned today without complaint. Though I do apparently have a point of water ingress I'll need to look into.



Chasing that is a job for when there are less bits of tree getting blown around and inserted into my ear by the wind. To be fair though, she had been travelling at speed through absolutely torrential rain immediately before I spotted that so I don't really begrudge the car for letting a bit in.

Hopefully next month I won't need to depart in a panicked powerslide because my house is flying to bits in the wind...

[Zelandeth]

Little care package arrived this morning.



Contents:

[] Air filters (X2).

[] Distributor cap.

[] Rotor arm.

[] Oil filter housing gasket (not sure if I need it yet, but it was £1.34, so made sense to get it in stock).

[] Number plate light lenses (X2). Quarter of the price of used ones on eBay for some reason.

[] Drive belts (PAS & Alternator/Fan).

The sheer size of the distributor cap still surprises me. Keyring for scale!



I've also got a set of timing cover gaskets (the later type as used on the 6.0 version which are apparently actually oilproof) on their way too. Once they arrive I'll get stuck in. I want to clean up and lubricate the distributor advance system, but given the amount of bits that need to come out to get at it, I figured that it made sense to get everything together so I could tick as many things off in one pass as possible.

I know the distributor cap was changed back when the previous owner had the car, but the stub for the breather system has snapped off (looks like someone has tried to glue it back on at some point), so it needs changing.

Need to confirm the hose sizes involved then will get some marine hose ordered up with a view to getting the fuel system gone through end-to-end so it's all guaranteed to be ethanol safe. Given the lack of any markings whatsoever on most of it my assumption is simply "I don't consider it safe until you've changed it." Especially in light of the V12 XJS being somewhat known for engine bay fuel leaks with the obvious potential for fire as a result even before they went and stuck ethanol in all of our pump fuels!

[white exec]

If high under-bonnet temps are an issue (they were on Rover V8, and even more so on MGBGTV8), could there be an argument for having the engine cooling fans always running at extra-low speed, whenever engine is running? This would be easy to achieve, could shift a lot of heat, and would involve less wear-and-tear than having the AC running full-time, which some owners in sunny places might do.

[Zelandeth]

Under bonnet temperatures are an issue on these cars (especially in the V of the engine and at the rear of the engine bay), though the car being fitted with a (huge) viscous can means that there's always a pretty decent amount of airflow whenever the engine is running.

Reconfiguring the power feed to the electric booster fan to provide some degree of post cooling after the engine is shut down does seem to be worth looking into though as under bonnet temperatures do spike quite alarmingly when the engine stops.

[white exec]

So it's running a viscous fan and an electric one? That sort of set-up is very old hat, and typical of the time. Could there be scope, later on, for fitting a pair of electric fans, and simply controlling them (high and low speeds) from our beloved 3-relay arrangement, which AC (and an under-bonnet thermostat) could also trigger?

The reduction in noise (and saving in power) by removing an engine-driven fan - even a viscous one - and moving to electric, is noticeable. I've done this on Dolomite 1850 and V8. In the case of the Rover, the only noise from the engine was a whoooosh of power, and farewell to the risk of losing fingers.

[Zelandeth]

Definitely something to consider for the future. Aside from anything else, the resulting fan activity on a hot start results in the car sounding like a hovercraft for the first five minutes or so.

The potential to save even 0.003% on fuel isn't to be sniffed at either!

[xantia_v6]

There are electric fan conversion kits available for the XJ-S, but they are rather expensive. The fans have to go behind the radiator due to structural tubes (and stuff) in front of the condensor. Fitting a single fan, or the right hand fan of a pair is tricky due to the proximity of drive belts to the radiator. I have formed the opinion that there is so much aluminium, steel and water under the bonnet that any heat soak will not raise the temperature very much.

As an aside, you will note that the electric fan relay shorts out the fan motor when the fan is not running. This is said to be so that the fan does not freewheel at excessive speeds when the car is driven at maximum speed, but few other manufacturers seem to have had the same problem...

[Zelandeth]

Yeah, access/availability of space is always going to be a challenge. I think if I were to look at an electric fan conversion for this given the amount of work involved, I'd probably want to see full speed control. Though to some extent you do already have that with the viscous coupling.

I hadn't spotted that they shunted the fan when it was off, though that does explain why it felt harder to spin than I'd maybe expected - might worry less about that then (I haven't actually confirmed whether that fan actually works yet) as it would be if it's shorted out by the relay!

Another one of those ways that they've over-engineered something beyond all reason maybe...in contrast to certain other areas which are delightfully shonky and needed an extra £0.10 spent on them. Yes, fuel injector lines, I'm looking at the lack of hose clips there...

(Yes...I know it's a stiffer than normal hose and that in theory if the hose is pushed fully into the ferrule it *should* be fine...but I don't like trusting my car to the word "should" where highly flammable liquid under high pressure is involved!).

[white exec]

Wouldn't a stalled/stiff electric fan just impede the air flow being created by the viscous fan - and add (minutely) to the overall air resistance? Intrigued by the thinking behind this.

Just read an informative article 'Braking a DC brushed motor' on the web, which talks about the physics of it, and motor stresses, but more interested in why Jaguar felt this was necessary. Are there many cars with both electric and engine fans ex-factory?

[xantia_v6]

Wouldn't a stalled/stiff electric fan just impede the air flow being created by the viscous fan - and add (minutely) to the overall air resistance? Intrigued by the thinking behind this.

The fan shroud has an internal divider stopping air leakage between the electric and mechanical fans, so the mechanical fan cools 2/3 of the radiator and the electric fan 1/3. There are also rubber flaps to release excess pressure if the fans are impeding airflow at high vehicle speed.

[Zelandeth]

The electric fan is set to the left of the radiator so shouldn't impede the operation of the viscous can. Said fan is bigger than the one fitted to the early Volvo B10M coach chassis...seem to recall the engines they were fitted with were usually around 10 litres in size. Tuned for torque rather than power, but thinking about it the numbers probably don't compare that badly, albeit with a very different sort of duty cycle in mind.

Imagine having the electric fan able to freewheel would probably assist slightly in terms of airflow purely by ram air while the car is moving though.

Seem to recall there's some sort of flap arrangement in place to prevent hot air from the engine bay being pulled back through the radiator by the main fan when the electric one isn't running.

[white exec]

One of the advantages of (twin) fans ahead of the radiator is that, under all running conditions, hot engine bay air cannot get pushed through the radiator.
If that were my engine bay, I'd be looking to update, improve and de-clutter, and maybe create some useful space ahead of the rads.

Many British engineers were reluctant to start with a clean sheet, or to back-track when something didn't work or became over-complicated or mechanically cumbersome. Comparing under-bonnet on Jaguar and Rover, of similar vintage, is quite instructive. Rover didn't always get things right, but at least the result was always tidy - even when working from essentially the same parts bin.

[Zelandeth]

As I recall the idea of situating pusher fans on the XJ-S is frustrated by the location of bracing spars behind the radiator grill. Nothing is insurmountable though.

I think the fans are probably a ways down the priority list though. Sorting the shortcomings in the actual circulation path would probably happen first as that can do quite a bit to boost the overall efficiency of the system. I need to dig it out, but there was an article in Practical Classics where a gent had basically explained all the shortcomings in the system and how he had resolved them. It got rid of quite a bit of spaghetti as I recall.

Tyres are definitely the major thing next up, and it will be expensive. Before I do that though I'm getting the tracking checked. If I'm spending more than a grand on tyres I'm going to make sure I'm looking after them! I'm pretty sure it's out a ways anyway. The steering wheel is slightly off straight and she tramlines something rotten on broken surfaces, especially under braking. I need to ask Formula 1 about tyres anyway, so may as well get the tracking done while I'm there.