Jaguar X300 Parts interchangeability

[Simpo Two]

Jaguar steve said:

Not even close to either the previous ancient Jaguar XK engine or the later gorgeous V8s and behind any contemporary six cylinder motors from BMW, Rover or even the Renault/Peugeot/Volvo 2.7V6

My 1990 4.0 Sovereign had the AJ6 straight six; it was great. Did it become the AJ16 for emissions?

[a8hex]

Jaguar steve said:

londonbabe said:

I remember a quote from someone at Jaguar describing the AJ16 as having "the power of the Lexus V8 and the refinement of the BMW 6 which is the exact opposite of what we would like"

I was working as a mechanic at a multi franchise car dealer when the first version of that engine was launched in the 3.6 XJS and a little later in the XJ40. My experience both then and later putting some 50k miles on my own X300 is it's a horrid engine in terms of refinement.

Not even close to either the previous ancient Jaguar XK engine or the later gorgeous V8s and behind any contemporary six cylinder motors from BMW, Rover or even the Renault/Peugeot/Volvo 2.7V6

Well the 3.6 from the XJS and the XJ40 wasn't an AJ16, so I can't comment about those.
Maybe mine was the only good one, although that doesn't seem likely.

Jaguar steve said:

Not even close to either the previous ancient Jaguar XK engine or the later gorgeous V8s

Oh you mean the glorious V8 which fell to bits at the rate of knots? The one where the cylinder bore linings dissolved, or the one where the water pump disintegrated or even the one where the tensioners on the timing chains took years to perfect, an obvious weak point on a double over head cam V8. Or by "later" do you mean the 4.2 or 5L versions?

In terms of the contemporary BMW sixes they only made little ones. The big block BMW 6 was out of production by the time the AJ16 was launched and it's role was taken over by a V8, the smaller one of which couldn't have pulled the skin off a rice pudding. I don't know about the M3 engine, I suspect that was probably rather nice, but a very different animal. So that leaves the M52, I liked the smaller versions, the 2.3L version was nice, but I found the 2.8L version not as smooth, certainly coming from the AJ16 to it I found it uncouth. Mercedes also had a 3.2L inline 6, it was similar in output to the AJ16 in 3.2 guise, I don't remember much about the ones I drove, I liked the R129 and we looked as getting one of the 320, but I don't remember the engine being any different to what I was used to. Mercedes then switched to bent 6s and that wasn't anything like as nice in my experience. We ended up with the diesel version instead.

[Jaguar steve]

Yes there's no denying in the first few years the V8 had some issues. Apart from Nicasil erosion which is ancient history now and affected other marques too none of them are insurmountable.

This specific discussion concerns refinement and having run a AJ16 XJ6 and two V8 XJ8s for something like 150k miles in total I can assure you in terms of engine noise vibration and harshness the V8 is ahead of the AJ16 by a country mile.
Run both side by side as I did for a month or so when I first dipped my toe in V8 ownership it very quickly became clear the two engines really are are chalk and cheese in this particular aspect, so much so I really can't see anybody whose experienced both for any length of time could reasonably suggest otherwise.

[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?

[AdeTuono]

4 months on; I'd have taken it to a specialist by now.

[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.

[Jaguar steve]

Apart from the fact it's about to run out of fuel I can't see anything wrong on the video.

The symptoms you describe suggest there may be an air leak somewhere in the induction system, more likely downstream of the MAF, . I'd check right through all the joints and hoses and connections from the air filter box right up to the inlet manifold including the brake servo.