you do know of course that most xj40 diff noises are due to worn output
bearings? teh design of the diff requires these bearings which will usualy
not last the life of the car or the diff. they can be replaced with the diff
in situ. now if it was the input bearing then it has to come out. 2 yrs ago
I dumped my 88 xj40 with 230k. had all the typical probs. now I have a cad.
deville with a third of that mileage many more serious problems and a car
payment. big mistake

The 88 XJ40 was perhaps one of the most problem plagued, unreliable vehicles
ever launched. That being said, it was a great highway cruiser and with an
undeniable elegance. Through analysis of warranty claims, customer and
dealer complaints, within 60 days of its launch in Spring 1987 (as an 88
model) the Jaguar service organization in the States had documentd 57
"unfixable" faults through. These were the results of either substandard
design, poor manufacturing processes, substandard componentry or a
combination of all three.

By the next Fall they released a "Product Enhancement" kit to recitify a
number of the most serious faults for which they couuld finf a repair. They
then set about fixing the issues one at a time in production. Thus, the
earliest XJ40s still on the road are by now likely to have recieved updates
to later spec. Many of the issues weren't corrected until the launch of the
X300 facelift in '94, some argue even that car still had a number of
undesireable issues endemic to the original, BL-penned XJ40 design.

Differential noise & early failures were indeed a problem. GKN, the
manufacturer, could not achieve a consistent setup. Along with Adwest,
Chloride and a number of other vendors, post -89 Ford management fired them
and replaced them with top drawer producers like ZF, Varta, Bosch, Denso,
etc. While the list of issues with the '88 are now funny to review, they
were a nightmare to deal with if you were, as I was, a Jaguar Service
employee in the late '80s.

Other issues: ride leveling system failures (numerous issues), dead
batteries, bulb-failure module failures, odometer readings that reset to
zero automatically, fogged windscreens (defrost design), single wiper blade
that wouldn't clean the screen (this issue remianed through X350), tinny
door panels that rattled when closed, bad panel fits, steering wheel shook
when the door was closed, transmissions that wouldn't go into park (ZF
claimed J-Gate cable design), seat control switch location - inandertent
operation, no tow hooks, blown headlight fuses (frozen washer bottles due to
no screen wash fluid installed at factory, design put the washer motor on
the same fuse as the headlights...brilliant!), front a-frame spring bucket
bolts fractured (front suspension collapsed), glove box door fit &
operation, exterior door handle failures, tail light lenses discolored from
UV exposure, brake light switch stuck on (tail light lenses melted), etc.,
etc.

When they were new, it was not unusual to find XJ40s that had amassed over
50 warraty claims by the end of their second year of ownership. The record
for an XJ40 buyback was 130 warranty claims in 3 years...the law at that
time in the USA was 4!

This last point underscores one of the main reasons Jaguar still exists: The
owners of these cars, as well as those of us who worked for the Company,
loved these cars and just wanted them to work. Every once in awhile I'll see
one cruising along the highway, or sitting on a used car lot and chuckle.