X100 convertible : 4.0 XKR vs 4.2 V8 ?

X100 convertible : 4.0 XKR vs 4.2 V8 ?

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Bossv8

Original Poster:

51 posts

141 months

Tuesday 24th January 2017
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For the same price, you can get XK X100 (before 2005) convertible with the 4.0 supercharged or a 4.2 naturally aspirated.
The 4.0R has more power and torque but the 4.2 would be newer, sound better and get a better gearbox.

Which one would you pick up? Why?

edward1

839 posts

271 months

Thursday 26th January 2017
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Depends on your anticipated usage and how important the power is for you. The normally aspirated one isn't exactly slow but at the same time isn't particularly fast by the standards of the modern hot hatch.

In the end buy on condition, a well maintained 4.0 will no doubt be less trouble than a poorly maintained 4.2, assuming the tensioners etc have been done on the 4.0. There will probably also be some subtle exterior styling changes between the 2 cars as well.

Bossv8

Original Poster:

51 posts

141 months

Thursday 26th January 2017
quotequote all
Yes of course. I even find the early shape a bit less bulky than the latter.

But the 5sp gear box I read is much better than the 6sp.

P700DEE

1,132 posts

235 months

Friday 27th January 2017
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The Mercedes 5 speed fitted to the 4.0R is a better box than the ZF six speed fitted to all 4.2s but the extra ratio allows a better cruise and improved mpg. There is no comparison between the drive (power) of a 4.0R and a 4.2NA the surge from the Supercharger is why you buy an R and why they are just better. The 4.2 is the better sorted engine but by now most 4.0 engines will have had the potential issues addressed. I have had a 4.0R for 12 years and had a 4.2NA for three during which I wished I had bought a second R.

Bossv8

Original Poster:

51 posts

141 months

Sunday 29th January 2017
quotequote all
That's interesting. In what regards is it a better gearbox ?
I am now looking at a 2001 model. I think those have had all the problems sorted or are there still things to be sorted on those?

P700DEE

1,132 posts

235 months

Monday 30th January 2017
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The Mercedes 5 speed box is slightly more reliable, and never suffered from the "lurch"

Jaguar steve

9,232 posts

215 months

Monday 30th January 2017
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Bossv8 said:
That's interesting. In what regards is it a better gearbox ?
I am now looking at a 2001 model. I think those have had all the problems sorted or are there still things to be sorted on those?
A XK of that age should be fitted with the revised AJ27 engine which means the weak water pumps and throttle bodies and Nicasil linings you may read about are no longer of concern. Secondary timing tensioners still are though and you'll need to either see a receipt showing the metal bodied versions have been retrofitted or take the Rh cam cover off and have a look yourself.

Apart from that chances are the car will be seriously in need of a gearbox and diff oil change and you'll need to be very aware of floorpan and general corrosion issues with the XK8 and also the condition of suspension, tyres and brakes.

As with any old car buy very carefully on condition and history and IMO budget for a full fluid change.

Bossv8

Original Poster:

51 posts

141 months

Tuesday 31st January 2017
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The car i am considering as a low millage 50.000 miles.

Bossv8

Original Poster:

51 posts

141 months

Wednesday 1st February 2017
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At what month of 2000 or from what VIN were all mentioned issues solved?
Thanks.

Jaguar steve

9,232 posts

215 months

Wednesday 1st February 2017
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Bossv8 said:
At what month of 2000 or from what VIN were all mentioned issues solved?
Thanks.
Assuming the XK was revised at the same time as the XJ then all the early throttle bodies should have been changed under a factory recall and engines should have been revised from AJ26 to AJ27 for the 2000 model year - you can tell from the XJ VIN, but I don't know if the same applies to the XK - which version is fitted.

AJ27 engines have steel liners instead of the Nicasil coated bore in the AJ26, revised water pumps with a metal not plastic impellor and mk2 secondary tensioners as well as other modifications. Some early cars may have had a later engine fitted under warranty and you can identify these by the presence of a green tag on the back of the RH cylinder head. At sometime in the production run the ZF5 5 speed gearbox fitted to the N/A cars had modified transmission components.

You'll need to make sure the 3rd gen metal tensioners and later water pumps have been retro fitted to both the AJ27 and 27 versions.