1. Overview of various XJ40 models.
The Jaguar XJ40 was the result of a 10 year design exercise with the
Jaguar design department attempting to best the classic design of the
first generation XJ6. The XJ40 prototypes began with a body design very
similar to the final result, wandered through the boxy, angular shapes
which were popular in the early-1980s, before returning to the body
style that we know today as the XJ40.
While the XJ40 body design was simplified greatly over that of the
series III XJ6, the XJ40 electrical system became much more complex.
If you interested in the new XJ40 model, then get a copy of the
September 1994 Jaguar World magazine. They have an excellent 5 page
article on buying a used XJ40. Currently, large numbers of early XJ40's
are being dumped on the market at low prices due to many first owner
leases ending. The jury is still out on the XJ40, but the picture which
appears to be evolving is that, while early models had some some serious
problems with their new electrical and mechanical systems, the later
XJ40 models appear to be quite robust.
"A business colleague and I bought our XJ40's from the same dealer,
within a month of each other. This was two years ago. He has since
sold his, because there was precious little that didn't go wrong with
it during that time (Dropped valves, a new radiator, a new clutch fan,
a gearbox, a rear end, dropped valves, instrument panels, Window
motors? a radio, an aerial, 4 door handles, (same door??), new shock
absorbers, air conditioning compressor, new brakes (discs) wheel
bearings and power steering pump). Many more miscellaneous towings!
All in less than 40,000 Kms.
But mine just kept driving along. By comparison, I did 110,000 Kms in
the same time and only had a fuel pump, new discs, and repairs
necessitated when the thermostat seized and cooked the engine. Other
than that one major repair (ouch) for a car of that mileage, I don't
think it is too bad." Peter Rebbechi(prebbech@ozemail.com.au)
"Likewise, I have now done 99,000 miles (160,000km's) and have had to
repair or replace nothing other than the usual bushes, pads, shoes,
shockers and not forgetting the tyres!!!! Tyres are the biggest
overhead of all! I have had a few punctures....it's amazing how sharp
a hawthorn thorn is! No electrical problems (other than bulb out
warning which I still live with). A little rust , mainly due to
(Jaguar dealer ) repaired accident damaged front wing. Still on the
original exhaust - minus the two mounting hooks above rear axle. I
have of course spent a small fortune on Jaguar dealer servicing."
Donald McGregor (Donald.McGregor@snl.co.uk)
2. Specific problem areas with XJ40's.
The early 1988 XJ40 models were the least reliable, with electrical
problems such as irratic guages, starter and fuel pump failures being
very common.
The service record for 1989 models is also poor though the model year
witnessed improvements such as new air vent designs that stayed in the
dash when moved instead of falling out into your hands, improved switch
assemblies for the cluster on both sides of the steering wheel column,
and some improvements in the electrical harness.
Metric tires: Early XJ40's came with metric sized tires. The metric
tires tend to be more expensive and come in fewer sizes than the more
common standard sized tires.
The 1990-93 years were ideal years for reliability. Improvements were
made to the power seat motors, improved sealing of the trunk (less
leaks) and more improvements in the electrical system. Things to really
look for are oil leaks at the right front corner of the head and rear
suspension problems. The oil leak tends to be the head gasket and can
be quite a problem. Look for oil between the distributor and the head.
The rear suspension should be converted to standard to get rid of the
hydraulics. After years of testing it has been found not to work
properly.
"A common problem with 3.6L AJ6 engines, is the intake manifold gasket
leaking. The gasket separates and protrudes from the mating surfaces
causing a vacuum leak and leaner mixture on the affected cylinder(s).
When the engine is cold, it isn't usually noticed because the computer
is creating a richer mixture. As the engine warms up to operating
temperature, the mixture is leaned to the point that a vacuum leak can
cause a rough idle." Loren Lingren
"Wheel sensors are the single biggest failure in the ABS. And, just
for the sport of it, a few diagnostic tips:
- The sensors get weak before they die totally. Causes intermintant
"failures".
- Proper testing requires a lab scope, and a reference
pattern/amplitude. however, you can do a rough-n-tumble by
hooking a AC volt meter to the unpugged sensor. Compare side to
side. At the speed *I* can spin the front wheels by hand, I want
to see about 1 volt. At about 0.7v, the system gets upset.
- Ever notice how badly XJ40's chew up the brake rotors? Well as
those filings from the rotors seem to gravitate (magnetate?) to
the ABS sensors. Before replacing a suspect sensor, try cleaning
all of the swarf from it and the reluctor wheel.
The ABS does a two pass self test. First test is done directly at
startup. When this passes, it will do the second part as soon as the
car exceeds 5km/h. This second test is dynamic, firing off the pump
and cycling all of the dump valves. This is what you are hearing. It
is normal. It shouldn't be very loud."
Randy Wilson