Jaguar X300 Parts interchangeability

[Alster370]

Been viewing jag threads for months but first time poster. Got a budget of £4k or so to get a jag this summer, narrowed it down to 4 options.

X300 4.0 Sovereign
X300 XJR
X308 4.0 Sovereign
Daimler Super V8 (would need to find another 3k at least)

If you cant tell by that list, im looking for a fast jag with the best ride possible and most of the toys, don't need it for high speed cornering, just wafting about. My problems with the X300 XJR is that I don't like the sport interior (which is always in black, yuck!) so If I did go that route I would look to swap the interior for a beige one from a sovereign or a daimler. The second issue is the ride, which I wouldn't enjoy, so im wondering if parts like the dampers and the springs are interchangeable across the X300 models, so I can fit an XJR with touring dampers, springs and obviously 16" alloys, allowing me the power of the SC AJ16 but with the comfort of the sovereign?

Another mini question, asked a jag trader about the difference in refinement between the x300 and the x308, and he said that the soundproofing is improved on the v8 and therefore the x308 is the quieter car. Just wondering If you guys agree with that, and if so to what extent is it quieter?

[Alster370]

a8hex said:

While the wood work and carpets are black the rest of the sports interior doesn't need to be. I'm pretty sure the same choices were available on the X300 XJR as they were on the X300 Sport. My Sport has the ivory leather so a lot of the interior is light.

As far as I know you can get a sport/XJR with walnut/oatmeal interior, but its rare to get a sport/XJR that doesn't have ivory with black wood, ive only seen one, might go test drive it actually.
http://www.autotrader.co.uk/classified/advert/201701211536837?price-to=5000&sort=price-desc&make=JAGUAR&radius=1500&advertising-location=at_cars&postcode=s188xy&model=XJ&onesearchad=Used&onesearchad=Nearly%20New&onesearchad=New&page=1

a8hex said:

If you want ride comfort then for the X300s there were 3 levels. When I tried them back when they were new I found the XJR was rather firmer than I wanted to live with. The Sovereign was softer than I wanted. The Sport's suspension was, for me, the Goldilocks level. They made 4L versions of the Sport, so you might want to add that to your list.

The last Jag I drove was a 4.0 sport, was nice and comfortable and handled bumps pretty well, but was one in need of TLC so Im not going to judge all sports on that example alone. My main objections to the sport are the lack of toys + the normally black & ivory combo, I prefer the seats in the sovereign too.

a8hex said:

The Daimler Super8 if you can stretch to one might be the ultimate wafter, but what about V12?

I dont think my wallet could stretch to that for daily fuel. Il be doing 120 miles a week so the 4L I6/V8 should average 20mpg, which is fine by me. I also know alot less about the V12 and while it may be smoother than both it is quite power deficient for its size and weight.

Im looking to buy from mid-May, and If I was to buy now these are the ones id consider:

X300 XJR - Linked above
X300 Sov 4.0 - http://www.autotrader.co.uk/classified/advert/201702011884587?onesearchad=Used&onesearchad=Nearly%20New&onesearchad=New&radius=1500&advertising-location=at_cars&make=JAGUAR&postcode=s188xy&sort=price-desc&price-to=3000&model=XJ&page=1
X300 Sov LWB 4.0 - http://www.jagwestlondon.co.uk/vehicle-details.php?vehicleID=11807&uid=4
X300 Daimler LWB 4 Seater (Rare) - http://www.ebay.co.uk/itm/1996-DAIMLER-SIX-LWB-AUTO-FULL-HISTORY-RARE-MODEL-WILL-APPRECIATE-VGC-BARGAIN-/142296156117?hash=item21218307d5:g:kPcAAOSwr~lYtVII
X308 4.0 Sov - http://www.ebay.co.uk/itm/Jaguar-XJ8-4L-V8-Sovereign-with-Over-7k-of-extras-from-new-F-J-S-H-/112325558160?hash=item1a271fff90:g:zR8AAOSwB-1YvR5Q
Daimler Super v8 - http://www.ebay.co.uk/itm/2002-Daimler-Super-V8-LWB-/262864107514?hash=item3d33ebf7fa:g:iREAAOSwTuJYszna

[Alster370]

Thanks for the input so far guys,

Ive gone though pretty much every X300/X308 thread on the internet, so im aware of the overall conclusions that the X300 is simpler, cheaper to maintain, has more charm and is more reliable, whilst the X308 is quieter, more economical, better handling and more refined in several aspects.


Im leaning towards the X300 mainly because of the engine, in that the stroke is larger than the bore, so you get lots of lazy torque, which is partly what I like in my current diesel. As far as refinements go, I care more for quietness, smoothness and the absence of creaks and squeaks. The X300 sport I drove was fine in my view, the only gearbox quirk I noticed was a bit of a jerk when operating the kickdown in sport mode.

Im not really looking for the jag to have any kind of sporty handling, the softer the better, I almost wish I could put it on those gorgeous 15" 70 profile donut wheels from the 1 series XJ. The faster it is the better, the softer it rides the better. Thats why my ideal choice would be the super v8, as its the speed of the XJR without the harsh ride, which was why I was curious if the suspension from a sovereign could be used on a X300 XJR, to achieve the same effect, as Daimler didnt do a super I6 unfortunately, and as far as ive read, its quite a task to swap in a SC AJ16 into a non SC car.

[Alster370]

Jaguar steve said:

I'll leave it up to you to decide whether you really want XJR BHP with Sovereign handling in something the weight and wallowage of a X300...

I appreciate what your getting at, I wouldn't be planning on taking corners at any speed, maybe just showing up some BMW drivers haha. I took some inspiration from that guy who put an XJR engine in a series 1 XJ.

If I get the right XJR I reckon it could be a good result. Any XJR that is ~£1500-2000 chances are either it needs paintwork, interior work or the suspension is worn though. If I can pick up one which just needs a suspension renewal then I can just replace all the suspension at the same time with the sovereign units. Got a least £4k to play with at the minute so could probably even replace the interior as well.

[Alster370]

Are there any specifics to how they made the x308 quieter? Ive searched and cant find much besides that the door seals are different on the x308, and obviously the door cards are different, so might insulate the cabin better, but I cant see why I cant replicate this on the x300. Other differences could be that the revised suspension better insulates from road noise and bumps?

[Alster370]

Thought Id give an update. Ended up bringing a turquoise 4.0 Sovereign 1995 from Dorset back to Sheffield two weeks ago, got it for £2500. Several problems, but overall condition is good for the price, and the interior is excellent. Been doing some general servicing, so new plugs, filters etc but have been trying to get the cause of this lumpy idle sorted out, which was there when I bought the car. Doesn't affect actual driving, just idles poorly, as if one cylinder isn't firing properly, you can hear it pretty definitely at the exhaust end.

I've got a code of P1621 from a cheap reader and had a look at threads and some seem to be resolved by replacing bad coils or crankshaft position sensors.

Can anybody offer some help to narrowing this problem down further?

[Alster370]

Been a while so I thought Id give an update. Rough running is still there, but its only in park for 95% of the time, ive been told its most likely clogged injectors. I also have poor response in park, hard to test in drive, but in park when stamping on throttle from idle the engine almost chokes out then catches up eventually. Unplugging the MAF makes the idle 10% worse but response is miles better. Couldn't find any vacuum leaks, so Introduced one by taking one of the manifold lines off, and rpm increased by 150-200 rpm and idle improved slightly.

To give you an idle of this hesitation, using this video of a 3.2 revving as an example https://www.youtube.com/watch?v=QLBOH-G9f5g
from idle to 2000rpm, my car takes 40 frames, with the first 9 of those with the revs actually dropping after the throttle is pressed, corresponds to maybe a 150rpm drop, whilst the video car only takes 21 frames with no initial drop. (Both videos were recorded at the same fps, 25 I think.)

Any ideas?

[Alster370]

Could use some suggestions with this stumbling hesitation issue. see video here:

https://www.youtube.com/watch?v=meFJCD03oRo&fe...


You can actually see in the video that the revs drop before they increase! Also by twin fan cowling is loose at the bottom, looks like it has two tabs that slide into the support below, I guess these break alot?

[Alster370]

I don't think its ready for a specialist yet, im moving to Nottingham soon so I can get David marks to have a look at it with the jaguar diagnostics, but there are only a few things It could be in my mind. There's a lumpy idle. mostly in park, and then throttle hesitation, with some stumbling before it actually revs. Unplugging the MAF makes the engine instantly responsive, revs just fine, idle is faster but no lumpier Id say. Made me initially think it was a bad MAF, but my brother says because its using a different fuel map when unplugged, you cant rule out other components being contributors at least, to the issues.