XJ8 4.0 MPG?

Author
Discussion

mickrick

Original Poster:

3,701 posts

178 months

Friday 19th October 2018
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What can I expect out of one of these Motorway cruising?
TIA.

fatboy b

9,566 posts

221 months

Friday 19th October 2018
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There was me thinking this was a thread about a problem with an XJ8 doing 4 mpg hehe

Sorry, can’t help.

Hashtaggggg

1,926 posts

74 months

Friday 19th October 2018
quotequote all
me too

flying-banana

257 posts

77 months

Friday 19th October 2018
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I would say you could get excited if you see 30mpg, but it wouldn't be an exciting drive, keeping out of the way of the trucks!

Any stop/start driving will kill the numbers, maybe as low as 15mpg, mid 20s should be achievable if you're not too heavy with your right foot

mickrick

Original Poster:

3,701 posts

178 months

Friday 19th October 2018
quotequote all
I'm guessing 18-20?
Found a 2000 model with 43,000 on the clock, clean as a whistle in LHD, I live in Spain and I fancy it....

Jaguar steve

9,232 posts

215 months

Friday 19th October 2018
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4.0 gearing is slightly higher than the 3.2 X308 so MPG may be marginally better under some circumstances.

Driven reasonably sensibly and with anticipation the 3.2 will return mid to high teens round town in stop start traffic, mid 20s out of town and high 20s on a long cross country drive.

30 MPG is a myth unless you're doing a steady motorway cruise for hours then you might just touch that.

Simpo Two

86,596 posts

270 months

Friday 19th October 2018
quotequote all
fatboy b said:
There was me thinking this was a thread about a problem with an XJ8 doing 4 mpg hehe

Sorry, can’t help.
Me too! I could get 4mpg out of my XJ40 4.0 Sovereign by booting it in second smile

Pity the designation 'Sovereign' got lost along with everything else. When it had that on the back you knew you had all the toys (apart from the fold-down picnic tables which were the preserve of the Daimler tag). Happy days.

FWIW the XK 4.2 will do over 30+ on motorways.

gamefreaks

1,993 posts

192 months

Friday 19th October 2018
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Not sure about the 4.0 but 4.2 will get over 30 on the motorway and under 20 in town.


mickrick

Original Poster:

3,701 posts

178 months

Saturday 20th October 2018
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Thanks for the replies.
So, apart from timing chain tensioner, coolant tower, and water pump upgrades, is there anything else I need to look out for?
What about nikasil bore issues? what years were these?
They seem to be a good solid reliable car?
TIA.

Jaguar steve

9,232 posts

215 months

Saturday 20th October 2018
quotequote all
Rust.

Pay top money for the best one you can find.

The world famous JS X308 Buyers Guide thumbup

OVERVIEW

To avoid model confusion between the 8 XJ models the 1997-2002 V8 engined XJ8 can be referred to by its factory designation as the X308. The all new at the time V8 engine in the 308 has similar architecture to current cars and is available in a 3.2, 4.0 with VVT and a supercharged 4.0 and all versions are 5 speed auto only.
Engines were revised in the late 1999 model year from the original AJ26 version to AJ27. A car fitted with the revised engine version can be identified by a VIN number ending in five , not six digits. AJ26 engines suffered weak water pumps, thermostat failures, secondary timing chain tensioner and throttle body failures and had a Nicasil coating applied directly on the cylinder bore walls rather than using conventional steel liners pressed into the block.
ENGINE NICASIL
Some Nicasil coatings errroded due to a combination of high Sulphur content fuel and repeated short trips. Sulphur maximum allowable limits in petrol were lowered considerably in Jan 2000 so any pre 2000 Nicasil coated engine that you know for sure is OK now should not be any concern. Several Nicasil engines were changed under warranty so you may find a pre 2000 car with a later steel lined engine fitted - identify this by the presence of a green tag on the head buried at the back of the RH bank and the engine change should also be recorded in the history. Symptoms of erosion and loss of compression are fast cranking, poor cold starting, a lumpy idle and heavy oil deposits in the breather system and air intake. Crankcase pressure will be high too – a quick check for this is to undo and slightly lift the oil filler cap at hot idle. There should be little or no internal pressure or fumes escaping. Jaguar dealers can perform a blow by check to determine engine condition. A good condition engine will show less than 20l/m anything over 30 l/m is shagged.
ENGINE COOLING
Impellors on AJ26 water pumps can disintegrate giving a loss of efficiency leading to overheating and potential head gasket failure. An early pump can be changed to the later version with a metal, not plastic impellor. The temperature gauge is software driven and is not always an accurate refection of actual coolant temperature.
For an indication of water pump efficiency, remove the coolant header tank cap when the engine is absolutely stone cold, start up and gently increase engine speed. If the water pump is healthy you should see a strong stream of bubble free coolant into the tank.
Thermoststs can jam either open or shut.
You may be able to identify the later type of pump by the presence of a black plastic, not metal gasket, but the only certain way is to remove the pump and have a look. Spring type coolant hose clips can loose tension and let pipes blow off and some plastic parts on the hoses, unions and thermostat housing are very delicate. Check all over the engine compartment for evidence of coolant leaks, particularly around the thermostat/filler cap tower and coolant (valley) pipes underneath the inlet manifold as well as around the expansion tank hidden under the front of the nearside wing. Leave the engine idling to make sure the cooling fans kick in. Sniff around too as hot coolant has a distinctive smell. Auxiliary heater pump failures cause loss of heat output in the cabin at low engine RPM. Two types of coolant available for the XJ8 - don’t mix the later orange long life one with the earlier green one.
ENGINE THROTTLE BODIES
AJ26 throttle bodies all ought to have been changed to the later design under a factory safety recall. Some of the early bodies suffered from failing actuating motors causing to the engine to cut out completely on a high speed overrun. The later design should have been factory fitted to all cars from VIN 043775 onwards.
SECONDARY TIMING CHAIN TENSIONERS AND CHAINS
The only post AJ26 revision engine issue that remains is the secondary timing chain tensioners. These were replaced by a mk 2 version in Oct 1998 from engine no 98102106XX but the mk 2 type still had a plastic body which can crack or break up leading to slipped or broken chains. Mk 1 tensioners are actuated by engine oil pressure and failure can often be identified by a sharp rattling noise similar to a bicycle chain dragging on the chain guard on a cold start. The mk2 type is permanently tensioned by an integral spring instead which means it’ll usually fail silently.
A permanent solution is to retro-fit the later mk3 version tensioner made with a metal, not plastic body from the later 4.2 incarnation of the V8 engine. Jaguar issued a TSB in 2005 advising the fitment of these to the X308. Only way to be sure of which tensioners are fitted to an 308 is to either have a receipt with tensioner part numbers C2A1511 and C2A1512 which are the metal bodied type and the required 4 shorter bolts to fit them on it relating to that particular car or remove the RH cam cover - the LH is a PITA to get off - and have a look. A reddish/orange (mk1) or cream (mk2) plastic tensioner body is bad news, a grey aluminum metal one (mk3) is good.
The cam phasing on the V8 places uneven loading on the timing chains and they can stretch at high mileages or on neglected cars. If this is identified then a full chain and tensioner replacement is required costing up to £1000. If the chains and sprockets and guides are servicable then it’s a sensible move to fit the mk3 secondary tensioners which is a fairly easy DIY job. Tensioners cost around £75 a set plus a couple of quid for new bolts. Camshaft setting tools can be hired from the Jaguar Enthusiasts’ Club. Secondary tensioners can also be changed without any setting tools by tie wrapping the secondary chain to the exhaust cam sprocket and jamming the chain on the inlet cam sprocket with a wedge of wood to preserve the timing and removing the exhaust cam alltogether. Taking the cam out gives just enough room to ease the secondary tensioner away from position and fit a replacement. Chains slipping one tooth – usually on a cold start - will give a very rough running engine, more than one tooth slipped means exhaust valves will contact pistons.
A good general rule of thumb for engine condition is quiet running with just faint injector tick audible and internal cleanliness. Bright shiny metal inside the oil filler cap and dipstick along with clean oil and no evidence of leaks is a good sign, as is clear coolant that does not smell or taste bitter or acrid.
GEARBOX/ DRIVELINE
X308 gearboxes were marketed as “sealed for life” meaning no oil changes are called for in the schedule to reduce servicing costs. It's a ZF unit in the n/a cars and a Mercedes one in the supercharged cars. Any hesitation or engagement of Drive with a jerk as the engine speed rises means a potential gearbox failure looming and any gearbox stuck in 4th or 5th or only driving in reverse is beyond saving. A very faint gear whine may be heard in intermediate gears but any gearbox issues or concerns are potentially fatal. An oil and filter change might be all that’s needed to cure a gearbox malfunction like occasional reluctant or rough changes but that’s never guaranteed. Gear changes should be seamless and quiet and you should have instant response using the throttle, Sport switch and J gate selector.
Ideally the gearbox oil and filter should be changed at 50k then at 25k intervals; it's not a simple drain and refill on the ZF box as the final fill has to be done quickly with the engine running and within a narrow temperature range. There is no conventional dipstick for checking oil level.The ZF 5 speed box on the n/a cars requires Esso/Mobil longlife LT 71141 fluid also known as Lifeguard Fluid 5 and not conventional Dexron 3. The Mercedes gearbox in the supercharged version is also sealed for life but the same change requirement apply although you can use standard Dexron 3 in this box and once you have fitted a temporary dipstick it’s a much less complex job to do. Some transmission specialists offer a flush and change service done via the rather fragile oil cooler pipes in the radiator which also gets most of the oil otherwise retained in the torque converter out.
The same sealed for life marketing applies to the rear axle. Oil ought be changed but there’s no drain plug so old oil has to be vacuum extracted out of the filler plug. Refill with a API GL5 75 or 85/90 oil. Whiny diffs - a high mileage Jaguar speciality feature - can be quieted down considerably with EP140 or even EP250 oil.

BODY, PAINT AND CORROSION
Substantially better than earlier Jaguars. But look for corrosion round the rear wheel arches, round the front and rear screens especially underneath the screen rubbers in the bottom corners, bottom of the front wings, sill closing panels, jacking points and most importantly on the inner wing behind the front shocks on both sides. There's a reinforcing plate where the engine sub frame V mount is bolted to the body rail and some cars have corroded badly here. Corrosion around the same area may also be visible in the engine compartment on the top of the body rail around the heads of the two 10mm bolts that retain the top of the V mounts. Corrosion here is an MOT fail and a big welding job if the subframe has to be dropped. Another area to check is the joint between the rear of the front inner wings and the bulkhead. Body and paintwork is otherwise pretty good however some darker coloured cars suffer from peeling lacquer. Darker cars often appear to have slight but consistent orange peel in the lacquer all over the body too but you can use this to spot inconsistencies and start thinking about accident damage repairs. Bumper corners are susceptible to damage and bumper mounting brackets can corrode. Lacquer on the XJ8 is soft and easy to scratch with careless washing Providing you can’t actually feel scratches with a thumbnail and the paint colour underneath is OK it’s possible to restore the bodywork to a glossy finish with a mornings detailing if that's your thing. Stripe down body flanks if car has one is hand painted and not always completely straight.
INTERIOR
Very cozy given the size of the car. Always leather with different levels of trim and seating style. Wood trim clips on and is easy to change to different design. Driver’s seat back and steering wheels tend to suffer from wear. Head linings can sag. LWB version has extra room in the back. Check everything and repeatedly cycle the whole climate and a/c system through all vent operations and temperature range and run the interior fans at high speed while doing so and listen for vibration. Foam can get dislodged from the flaps and jam in the fans.

SUSPENSION, TYRES AND BRAKES
X308s are heavy and can be hard on suspension and brakes. Listen and feel very carefully for any clonking or knocking over bumps and make sure the car comes to a straight judder-free stop under both light and hard braking. Stop the car on the handbrake to make sure it works. A sharp rattle heard and felt through the steering over bumps combined with a little free play in the steering wheel may be a worn crush joint on the lower steering column. A clattery rattle from the rear is likely to be either failed shock bushes or worn rear silencer hangers. A soft clonk from the front might just be anti roll bar bushes. X308s with weak rear A frame bushes or worn rear hub pivots will tend to self steer and wander about under hard acceleration.
Look and feel round the tyres for uneven wear patterns; any suspension wear or bush failure allowing incorrect geometry will cause tyres to feather badly and excessive wear in the inside edges of the fronts is sometimes a symptom of excess negative camber from wishbone bush or ball joint failure rather than excess toe out. There is a subtle bifference in the two wear patterns with excess toe out usually causing a even slope across the tyre and excess camber more likley to show a sudden step up in wear on the inside 25%. Slight and even feathering inside and out is normal on the front tyres.
308s are very sensitive to wheel and tyre imbalances or damage, typically you'll feel a steering wobble between 50-70MPH and possibly vibration through the seat from anything over 45MPH if there are any tyre problems or buckled wheels. A Hunter Roadforce wheel balance may help diagnosis. Incorrect tyre pressures and knackered or faulty tyres will severely influence handling and ride. Most X308s exhibit a faint exhaust harmonic around 50 and another one at 65MPH. You might possibly experience a hint of driveline vibration through the body too. Don't expect too much in the way of the legendary Jaguar ride quality either - it's acceptable on touring (black shocks) suspension and 16" wheels but sport suspension cars (green shocks) have higher damping rates and have a thicker front anti roll bar and one fitted on the rear too which when combined with larger diameter wheels and lower profile tyres gives a hard crashy ride on poor roads. CATS suspension may be fitted as an option to any X308. CATS has electronically controlled valves in the shocks to vary the damping rates depending on driving style. Identify CATS by the presence of a plastic cover over the top of the front shock absorber with a lead going into it.
ELECTRICIAL/ OBD2 DIAGNOSTICS
Electrical systems are generally pretty robust. As with any old car you might have the odd problem so check absolutely everything works. X308 is OBD2 compliant and a £20 code reader plugged into the socket in the driver’s footwell will help diagnosis a lot. Electric aerials are easy to damage but easy to replace, there are occasional O2 sensor, airflow meter and brake light switch failures. Non working key fobs usually need nothing more than new batteries, a clean and easy DIY reprogramme. 308's need a strong battery to avoid random error messages appearing on start up. If you get one – usually TRAC FAIL – the battery is on its way out or needs several days on a trickle charge to bring it back up to full capacity.
BUYING AND LIVING WITH AN XJ
Generally the 1997-2002 XJ8 is a strong car and capable of big mileages if maintained well and not abused or neglected. It's mostly easy enough car for a competent DIYer to work on and parts are pretty reasonable and in good supply from several independents and the Jaguar Classic Parts scheme. The few specialist tools required can be hired from the JEC.
Expect around 26/8 MPG on the motorway or touring, between 20 and 24 around town and mid teens or less if you're nailing it in a n/a car, the supercharged versions typically use more. Quality tyres start around £100 a corner in 16" diameter size. Early cars fall into a cheaper VED bracket then later ones. Servicing schedule is annual or 10000 miles. 70k service is the expensive one on n/a cars
3.2 does 0-60 in 8.1s and the 4.0 is a second quicker.
Shortening intervals between servicing and using a genuine fully synthetic oil is worthwhile IMO. It’ll help protect the timing chains and give a small improvement in fuel economy. Keeping oil topped up to the maximum mark - both my V8's have used a little - is a plan too as it reduces stress on the oil and both reduces the possibility of oil starvation on rapid cornering and seems somehow to make a subtle improvement in refinement. A through rust proofing and full fluid change is a benefit too if you want to preserve the car. Waxoil has the effect of lubricating suspension components and a good soaking - not anywhere near the brakes 'tho please - will subtly improve the ride quality.
Keeping the inside of the throttle body and the elements of the airflow meter spotlessly clean as well as the 2.5mm calibrated bleed hole in the breather system will stabilise and improve throttle response and consistentency especially at small openings. Again it's a subtle but worthwhile improvement. Any leaks in the air intake or breather system need fixing.
Providing the suspension components are all OK and the tyres are reasonable a occasional Hunter full 4 wheel laser alignment geometry check and reset will improve feel of the car dramatically. Small changes in tyre pressure have a unusually big influence on how the car drives too.
One last thing. A software error means its a very bad thing to start an X308 from cold and then switch off again straightaway or before allowing the temp gauge to move off the cold section of the scale. There's a chance are it’ll flood when you next start and wash all the oil of the bores and it’s a right PITA to get it running again.


mickrick

Original Poster:

3,701 posts

178 months

Saturday 20th October 2018
quotequote all
Wow! That's a pretty comprehensive reply! Thank you so much!
I'm hoping the dealer will respond to my e-mail on Monday, otherwise I'll call.
If I get the right answers, I'll book a flight and go have a look.
Thank you smile

mickrick

Original Poster:

3,701 posts

178 months

Monday 22nd October 2018
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Saggy headlining! Any tips on this?
TIA. smile

Jaguar steve

9,232 posts

215 months

Monday 22nd October 2018
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mickrick said:
Saggy headlining! Any tips on this?
TIA. smile
Myrtle Ltd make a replacement headlining that's flexible enough to roll up and get in through a door. No need to have the screen out
Vid on utube.

mickrick

Original Poster:

3,701 posts

178 months

Monday 22nd October 2018
quotequote all
Thank you sir! Found them smile 200 quid fix, nothing to stress about then smile

Edited by mickrick on Monday 22 October 12:20

prand

5,999 posts

201 months

Monday 22nd October 2018
quotequote all
In my experience, I should have read and paid attention to Jaguar Steve's advice on the gearbox.

i.e. any hesitance in selecting gear, or subsequent shunting when driving off is a sign of a gearbox on its way out and if you are interested in a car, walk away. As my poor mum and dad found out on the autoroute in near Lyon.

Fortunately I had very decent European recovery cover to get the car repatriated. Still cost over £1500 for a second hand gearbox to be fitted though.

I think I got around 30mpg on cruise.

Jaguar steve

9,232 posts

215 months

Monday 22nd October 2018
quotequote all
prand said:
In my experience, I should have read and paid attention to Jaguar Steve's advice on the gearbox.

i.e. any hesitance in selecting gear, or subsequent shunting when driving off is a sign of a gearbox on its way out and if you are interested in a car, walk away. As my poor mum and dad found out on the autoroute in near Lyon.

Fortunately I had very decent European recovery cover to get the car repatriated. Still cost over £1500 for a second hand gearbox to be fitted though.

I think I got around 30mpg on cruise.
Transmission failure on the XJ8 ZF 'box is frequently a broken A drum caused by a pressure spike from a faulty or sticking actuation valve.

ZF did modify the A drum from, IIRC a retaining circlip to spot welds at some time in the XJ8 production run but the real answer is to keep the fluid clean with semi regular changes. If you start getting the odd thump on gear changes get clean oil in asap - you might just save it.


mickrick

Original Poster:

3,701 posts

178 months

Tuesday 23rd October 2018
quotequote all
I've chased the dealer up, and he tells me the car is a US import.
I'm waiting to hears from the Lady who does the foreign car registrations here, to see if it's a possibility.
As much as I love living here, it's not a petrolhead friendly Country.
Ideally I need to find a Euro spec one.
Plenty in Germany, but they have huge mileage, and black leather.
I want a black car with cream leather smile I also like the very dark green....

mickrick

Original Poster:

3,701 posts

178 months

Tuesday 23rd October 2018
quotequote all
I've given up on this one. Nice car, but the dealer seems useless. Didn't respond to e-mails, and when I dialed the number in the advert, the Fellow on the other end tells me I've dialed the wrong number, and need to speak to someone else, as he was "out of the loop".
Fair enough though, he took my name and number, and his oppo called me back, but needed to ask someone else about some of my questions.
Then my Gestor Lady needed to see the logbook to give me some answers.
Called them back, got recorded message and escalator music, then told there was no one to take my call. Left a message, still no comeback.
Seems they're not bothered if they sell it or not.
Don't want to deal with them now.
And I think I want an XJR smile