Thursday 21st June 2018

Jaguar XJR X350: PH Buying Guide

The all-aluminium X350 was a radical departure for Jag, even if it didn't look it - here's how to buy a good 'un

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As subtle takes on the performance saloon go, the 2003 Jaguar XJR was almost anonymous to look at. Other than the 'XJR' badge on the boot, different alloy wheels and mesh front grille, this 400hp supercharged barge could slip past unnoticed.

Mind you, it was capable of slipping past most other traffic with no trouble at all. The 4.2-litre V8 also dished up 397lb ft of torque and used a slick ZF six-speed auto to see 0-62mph in 5.0 seconds, with an electronically ceilinged top speed of 155mph.

All of that subtlety was carried over into the cabin, which was opulently equipped but not garish - unless the original owner went a bit too far in the personalisation stakes. Still, you got a touchscreen for the infotainment and many included sat-nav, which now looks very out of date. More importantly, build quality in the cabin was a step up from the previous XJ, which could look tatty very quickly.

Jaguar facelifted the entire XJ range in mid-2007 and the XJR got deeper front and back bumpers and side skirts.

It's worth noting that the X350 generation of XJR doesn't ride with quite the same deft cushioning as the earlier generations, so be sure you're happy with this on a test drive before committing cash.

If you do go ahead, the cheapest out there start at around £5,500, but £7,500 is a more realistic budget for an early 2003 car. A really clean facelifted car with average miles will cost up to £14,000, which still bags you one of the most understated swift saloons ever made.

Search for Jaguar XJR X350s here

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Bodywork and interior

Corrosion is the biggest worry with the body around the doors, boot lid, rear windscreen frame and wheel arches. Anywhere there's a sharp contour or crease in the body needs to be looked at too. It's not rust in the normal sense, but a reaction on the aluminium panels to moisture. This can be sorted by a specialist body shop and the good news is this type of corrosion doesn't spread like normal ferrous oxide rust. There have also been reports of galvanic corrosion where Jaguar used steel rivets to join aluminium panels, while others point at poorly applied paint or iron filings from when the body panels were pressed.

You should also inspect the underside closely for rust on the front and rear subframes, which are made from steel.

Parking dings can be expensive to put right because aluminium is more brittle and harder to repair, so expect larger bills for this sort of work. Check for any previous accident repairs or signs of damage.

Rear parking sensors can fail when water gets into their bodies set into the bumper. Removal and cleaning should get them working again.

Door handles can snap and electric windows stop working, requiring a new motor.

Engine and transmission

The six-speed auto is claimed to be sealed for life, but changing the transmission fluid every 50,000 miles is recommended by independent specialists. This can help cure the slightly jerky take-off from low speeds.

A gearbox ECU reflash will also help cure any snatchy behaviour of the gearbox, which was a common problem when the car was new.

The coolant valley pipe that runs underneath the supercharger can fail and means the entire supercharger, charge cooler and intake need to be removed to replace the hose. The hose is cheap, but the work to access it is expensive, so look carefully for any signs of coolant leaks at the rear of the engine and underneath.

The cooling system's expansion tank can become over-pressurised and blow off the connecting pipe. A new pressure valve should sort this.

Suspension and steering

Rear wishbone bushes wear more quickly than you might expect in a relatively light luxury saloon, so reckon on changing them every five years for around £850. Or you can just have the old bushes pressed out and new ones put in for much less.

Air suspension will almost certainly fail at some point and show a warning light on the dash. The air bags wear out and begin to leak, but Bilstein released original-spec modules in 2012 that are cheaper than Jaguar asks at its main dealers. However these units still come in at around £750 each. A more cost-effective route is a reconditioned complete unit from £349 available from Air Dominance in the UK.

The ECU's Body Processing Module can fail and affect the suspension. New ones are available for £500 or used ones that have been tested and working for £100.

Wheels, tyres and brakes

Jaguar issued a recall for leaking brake pipes, so make sure this has been carried out on affected cars built between December 2005 and October 2006.

Rear brake pads wear quickly and electronic handbrake can fail.

Search for Jaguar XJR X350s here

Search for Jaguars here

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SPECIFICATION - JAGUAR XJR (X350)

Engine: 4,196cc V8 supercharged
Transmission: 6-speed auto, rear-wheel drive
Power (hp): 400@6,100rpm
Torque (lb ft): 399@3,500rpm
MPG: 22.3
CO2: 299g/km
Price new: £58,500
Price now: £5,500 upwards

[Etypephil]

They are much easier to own than the article suggests. If a car hasn’t got any corrosion by now, it never will have, they are as reliable as cars can be, the best thing though is that 500+ bhp and 700nm is easily and inexpensively obtainable.

[Etypephil]

trickywoo said:

Can the gearbox cope reliably with 700Nm?

That's about the limit for the gearbox, but unless one wishes to die, one cannot use all the bhp and nm for longer than a few seconds at a time.

[Etypephil]

8bit said:

Probably do-able but easily and inexpensively? Very much doubt it - how do you manage that?

A smaller supercharger pulley (10%), better intercooling, exclusive use of 99 octane and a bespoke remap (confirmed on a dynamometer) to fully exploit the fuel and increased boost. Less than £1,000.

[Etypephil]

dme123 said:

ZF6HP26 this car uses is rated up to 600NM. The ZF6HP32 is rated up to 750NM and was used in a handful of cars.

If you actually used that remapped 700NM and took the box at least 15% over spec you'd it in fairly short order. Most people who carry out this work seem to think managing 20k miles with the higher output in place constitutes iron clad reliability though!

AS for a few seconds at a time, how long do you have to put too much torque through a biscuit before it snaps? Same principle.

“Most people who carry out this work seems to think” is received wisdom, not experience; the proof of the pudding, and all that is 2008 X358, past 135,000 miles, used, and abused, never even had the transmission oil changed (on recommendation of ZF engineers), still going strong. Jags are not fitted with biscuits.😎

[Etypephil]

dme123 said:

I'll go with the experience of ZF, who designed the box and tested it for countless hours and rated it to 600NM and then designed another version that could actually cope with 700NM+. LIke all these things you'll get lucky for so long, but eventually it'll catch up with you. Maybe it means the box dies at 150k instead of 250k and you're happy with that, but to believe it has no impact whatsoever and carries no risk is foolish. It might also mean the box dies the first time you give it what for; that's what design specs are for.

The ZF6HP28 that the 5.0 litre supercharged cars used was also rated to 750NM.

Edited by dme123 on Friday 22 June 01:21

I am fortunate to be acquainted with a senior ZF engineer who gave me the “don’t change the oil” advice, and confirmed my belief that whilst every piece of machinery has designed performance specifications, those speciations include a significant safety margin. Naturally, venturing too far into that margin, too frequently, will shorten service life. The opportunity to use full bore acceleration, from a standing start, to delimited maximum, is however almost non existent, in any case, surplus torque is dispersed in burned rear tyres, not by overloading the transmission in such a light two wheel drive car. Much greater stresses are placed on these gearboxes in other applications having far greater weight and four wheel drive grip, even in such vehicles they are rarely troublesome.

Edited by Etypephil on Friday 22 June 04:40

[Etypephil]

8bit said:

I still don't think you'll get near, let alone over a real, proven 500bhp with that lot. You got any links?

I didn’t come here for an argument. I do indeed have before pulley, after pulley, plus after pulley and final optimisation graphs, all from the same dynamometer, thanks. You, of course, are free to think whatever you wish.

[Etypephil]

sjc said:

In fairness the parts alone come to three grand plus fitting and vat I assume , so a lot more than the £1000 that was suggested would get you there?

Paramount are extremely expensive. Powerhouse are the people for blower pulleys; less than £500 for the 10% one, fitted, including machining the supercharger snout for clearance. Any local radiator specialist will make a better charge cooler for C£200, dynamometer time and bespoke mapping can be bought for £50 per hour; I spent £250 on mine. Any more, and you are paying designer label money for what will almost certainly turn out to be a generic map unable to exploit your other modifications.

[Etypephil]

sjc said:

So you wouldn't need a better flow exhaust or cats Phil?

If one needs every last bhp & nm, to go racing, for example, otherwise they give very little extra, in return for a lot of money. A decent bespoke exhaust system incorporating 200 cell catalytic converters will cost around £2,200, to yield perhaps 25bhp; a poor deal in my view, although the car will sound much more powerful, the proof is on the dynamometer, not in the ears.

[Etypephil]

Stedman said:

Could you post the before and after pulley graphs please? Ta

I will be happy to early July when I am home; on a Land’s End - John O’Groats round Britain tour plus XJ 50th anniversary display until then.

[Etypephil]

This one is mine,
on its Winter wheels;

Summer ones;

From where the dog watches TV;