Jaguar XJ-S. Manual - part 171

 
 

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STORAGE 

 

This section provides tips for storing an XJ-S for extended periods. 

 

GUMMY FUEL:  Walt Osborn of Vintage Jag Works:  “We have the third car in the shop this year with stuck valves.  
This is becoming more of a problem as people collect more cars than they can take care of.  Some of the cars have been 
sitting for several years and the gasoline evaporates and leaves behind a syrupy varnish-like substance which gets on 
the valve stems in the cylinder head and causes them to stick in their guides.  They stick in the open position, the owner 
attempts to start the car and/or turns the motor over with the starter, and the piston fouls the valve.  Now the engine may 
start and run for a time and then start missing.  The miss is usually a bent valve.” 

 

FUEL STABILIZING:  Fuel doesn’t store well, it goes “stale”.  Fuel lines and other components may be affected by 
“varnishing”. 

In the old days of carburetors, it was usually recommended to cut off the fuel supply and run the engine until the fuel 
lines and float bowls are empty.  Unfortunately, this is more difficult to accomplish on an EFI system -- and may do 
more harm than good.  The electric fuel pump is immersed in fuel, and running it for any length of time with air in it is 
probably not advisable.  The worst thing for injectors is water, so condensation in empty fuel lines wouldn’t be good. 

The local auto parts store sells fuel stabilizers that can be added to fuel.  Before storing a car, add some fuel stabilizer to 
the tank and drive the car for a while to get it circulated throughout the fuel system.  Gregory Wells says, “Sta-Bil is 
one brand and these things are almost always available at boat dealers, since they are highly recommended for use in 
boat engines stored over the winter.” 

 

SOUR GASOLINE:  Arthur Smith says, “I found a reference to "Sour gasoline" (gasoline which has developed 
peroxides).  I found that enlightening since some of our British cars get stored for a period of time.  The reference was 
to a certain special rubber with stabilizers added that could withstand the "Sour Gasoline".  That makes me think that 
when one of our cars is stored for any length of time the "varnish" that forms will eat any rubber that is in the fuel 
system. 

“The information came from a BF Goodrich pamphlet and the distributer said the special rubber is not available.” 

 

ENGINE FOGGING:  The auto parts stores sell aerosol foggers for preparing engines for storage.  For the Jaguar V12, 
you will need two cans of aerosol fogger and three people.  When ready to park it, take both air cleaner covers off and 
disable the ignition and EFI -- you can disable both in one move by disconnecting the white/slate/blue wire to the 
ignition amp right on top of the engine.  Have one person stand on either side of the car with a spray can of engine 
fogger in hand while the third person holds the throttle open and turns the starter.  A good blast for a few seconds in 
both sides at the same time.  Turn off the starter and foggers at the same time, so you don’t run any fresh air through 
behind the fog. 

When it comes time to drive the car again, it is generally considered a good idea to change the oil promptly.  There may 
have been condensation during storage, which will contaminate the oil. 

 

TIRES:  The following was attributed to a Yokohama tech rep:  “He recommended two methods for storing vehicles.  
First, inflate the tires to 65 psi and leave the weight of the vehicle on the tires.  65 psi?  Modern tires will accept 65 psi 
for storage without damage.  You just can’t drive on them at this pressure without damage.  He did caution, however, 
that old stamped steel rims may not be able to take this pressure with out damage.  His second recommendation was to 

 
 

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keep the tires at the proper inflation pressure and to remove the weight of the vehicle from the tires (ie. put the car on 
jack stands). 

“The tech rep stated the reason for these two alternatives was that all tires contain nylon (typically, the nylon covers the 
steel cords and keeps the steel cords from working their way through the tread).  The nylon will develop a flat spot.  
The colder the temperature, the faster and more pronounced the flat spot will be.  Jag owners in Edmonton, Alberta, and 
Bismark, ND should have first hand knowledge of this. 

“A final recommendation, store the vehicle in a dark, well ventilated, cold room.  Light (specifically ultra-violet light), 
temperature, and moisture will damage the vehicle finishes and rubber over time.” 

 

CAR COVERS:  The general consensus is not to use car covers for long-term storage due to their adverse affect on 
ventilation.  Car covers are apparently better left to daily use only.  

 

BATTERY:  Herbert Sodher hails from the cold North where people store their Jaguars all winter and drive less 
valuable vehicles in the snow.  When stored that long, the battery in the XJ-S tends to go dead.  The alternator, clock, 
and some stereos and security systems put a small drain on the battery when the car is parked.  Jaguar recommends 
disconnecting the battery if stored more than a month, but that may be assuming too much about the condition of the 
battery and how easy the engine will be to start.  And, disconnecting the battery requires resetting the clock, all the 
stations on the digital radio, and possibly some security stuff, all of which is a pain. 

Sodher suggests the owner go to an auto supply store and purchase an on-board, fully automatic trickle charger and 
install it in the car.  One called the Mity-Mite is made by Schumacher Electric Corp., is rated at 1.5 amp, and costs 
around $30.  This unit is so small that Sodher attached it right to the front of his battery with Velcro, and the battery 
cover will fit over it (his battery is not the original -- it may require a different location for the Jaguar battery).  It comes 
with eyelet connectors that can be connected directly to the battery terminals.  Merely remove the nut on the clamping 
bolt from each terminal, put on the connectors, and reinstall the nuts.  The unit comes with a one-foot power cord, just 
enough to feed outside the battery box.  When parked for extended periods, merely run an extension cord into the trunk. 
 The unit will automatically charge the battery as required, and won’t overcharge it. 

 

 
 

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MODIFICATIONS 

 

ROUTING WIRES, HOSES, ETC.:  John Napoli says, “A really easy way to run wires or hoses or whatever across the 
firewall on an XJ-S is to go through on the passenger side (Federal models) access plate where the pedal box would be 
on a Brit version.  To get to it, remove the windshield washer reservoir (under the hood on the passenger side).  Now 
remove the bracket and the plate.  Plenty of ways to run your wires through there!  Note that there is another vacuum 
reservoir for the climate control system underneath, as well.” 

 

GARAGE DOOR OPENER INSTALLATION:  Paul Bachman says, “I took my garage door opener and replaced the 
battery with a 9 volt regulator (about $0.50), and installed it inside the center console.  Apparently, the entire wiring 
harness becomes an antenna, because the range actually increased (I expected it to be worse) when I buried the 
transmitter in a basically metal box.  Sure is nice not to have that stupid transmitter in my way any more.  I will install a 
third window switch between the two existing ones for the control. 

“The 9 volt regulator (LM7809) is a very simple three terminal device in a large transistor package (TO-220).  It is 
available or can be ordered at any electronics store for under $1.  One terminal goes to ground, one terminal goes to a 
switched 12 volt (+) source (can be found at the cruise control switch) and the third will provide a regulated 9 volt 
source.  The 9 volt source is connected to the (+) battery terminal or soldered to the appropriate place on the PC board 
of the transmitter.  The (-) battery terminal is, of course, connected to any handy ground (same place as the ground on 
the regulator).  If you can handle a soldering iron, it is quite simple. 

“This project is particularly practical if you have a garage door transmitter with a case that is broken and needs to be 
replaced anyway.” 

 

 

WEIGHT REDUCTION/RELOCATION 

 

The XJ-S is a heavy beast.  Let’s face it, it’s a luxury car, not a performer.  The best way to aggravate the Corvettes 
would be to pull about 800 pounds out of this car.  If you can do without the electric windows, electric door locks, 
stereo system, 5 mph bumpers, air conditioning, back seat, spare tire, carpeting, sound insulation, etc., etc., then go for 
it. 

Another popular way to reduce weight is to replace components with lighter versions.  Chad Bolles has replaced the 
radiator with an aluminum model, the bonnet with a fiberglass one, the A/C compressor with a smaller model, and other 
mods.  Effective but expensive. 

When making weight reduction modifications, bear in mind that such mods will affect acceleration in the non-
wheelspin realm by the proportion of total weight of the car; removal of 200 pounds will improve acceleration by 5% in 
a 4000-lb car.  In conditions where the wheels spin, weight reduction in the front of the car will help slightly, weight 
reduction in the rear will hurt slightly.  Weight reduction has almost no effect on top speed (other than how long it takes 
to get there).  Weight reduction has a similar effect on maneuverability as installing bigger tires; it may be negligible if 
the present tires are adequate.  Although it might feel different (and that alone may justify the modification), the actual 
timed performance may be insignificantly changed. 

Also bear in mind that the springs, shocks and other components are designed for a 4000-lb car.  If the weight reduction 
is significant, the car will effectively be sprung more stiffly and will ride higher.  If the stock springs are cut shorter to 
bring the ride back down, it will increase the stiffness even more.  All of this may be considered desirable in a car as 
soft as the XJ-S. 

 
 

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Weight reduction from points high on the car is preferable, since it will lower the center of gravity and make the car 
lean less in corners.  It is even beneficial to relocate components lower on the car. 

Weight reduction at the extreme ends of the car is also preferable, because it reduces the moment of inertia of the car.  
In other words, it reduces the car’s tendency to resist beginning to turn when going straight, and its tendency to keep 
turning when beginning to straighten out.  It is beneficial to relocate components from the ends of the car to more 
centralized locations. 

If weight is removed entirely from one end, it can change the balance of the car.  Since the XJ-S is obviously nose-
heavy, it would be helpful to either remove weight from the nose or relocate components to the rear of the car. 

Weight reduction on rotating parts, such as engine/drivetrain moving parts, wheels and tires, brake rotors, etc., can have 
a much greater effect on performance than general weight reduction throughout the car. 

 

 

COLD WEATHER 

 

ENGINE HEATERS:  If you live where it gets cold and use your Jag in the snow, it is highly recommended that you 
invest in an engine heater.  While preventing engine damage due to frozen coolant is the most obvious objective, those 
in the know point to many other advantages to engine heaters.  They reduce engine wear because running a cold engine 
results in accelerated wear.  They save fuel since a cold engine burns a lot of fuel.  They save wear and tear on the 
Lucas starter.  And they render the cabin heater operational much sooner. 

The ©1981 handbook says, “Provision is made on the right-hand side of the cylinder block for the fitment of an engine 
heater element obtainable from your Dealer under part No. C34403 - 110 volt.”  Apparently the handbook lies.  C34404 
is the correct part number for the 110V heater element, but the Parts Catalogue indicates that it’s installed in the lower 
radiator hose.  There’s no place in the block to put it. 

Jaguar provides part numbers not only for the heater and the elbow it fits into, but the two halves of the lower radiator 
hose as well: 

 

Heater element (110V) 

C34403 

 

Heater element (220V) 

C30381 

 Elbow 

C36996 

 

Hose - radiator to elbow 

C41103 

 

Hose - elbow to water pump inlet 

C41099 

It’s interesting that the elbow is just that; it replaces one of the bends in the single-piece lower radiator hose. 

If you’re not enthused about the Jaguar offerings, there are several types of generic engine heaters available in various 
wattages.  There are heaters that replace a freeze plug, although that option probably wouldn’t work too well on the 
Jaguar V12 due to the lack of freeze plugs in accessible locations.  There are heaters that are installed in a radiator hose, 
some of which include a pump to circulate the coolant.  There are heaters which attach to the surface of the oil pan, and 
there are dipstick heaters.  Some heaters have thermostats to turn them on when it gets too cold, and some have timers 
that will warm the engine in time for you to drive it. 

Of course, there are two schools of thought on the use of an engine heater.  Some recommend having it on whenever it 
gets below a particular temperature.  This makes sense if it gets really cold where this car is parked.  Hopefully, if you 
have the proper anti-freeze mixture, you won’t need to worry about this possibility unless your Jag is parked outdoors 
in the Arctic.  If so, building a garage with gas heat might be cheaper than paying the electric bills on the block heater. 

The other popular idea is to turn the heater on some amount of time before you’re gonna need the car, thereby having it 
partially warmed up and ready to go.  This will prove much cheaper than starting the car and letting it warm up, both in 
terms of cost of electricity vs. gasoline and in wear and tear on the engine.