Jaguar XJ-S. Manual - part 56

 
 

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8. 

Press the pulley with the new bearing into the idler arm. 

9. 

Do not peen this bearing onto the arm.  It will break.  TIG weld it into place-- it can always be 
drilled out if it fails again. 

10. 

Cut the long end of the bearing shaft as close as possible to the outer race of the bearing and dress 
it . 

11. 

Install your new idler.” 

Of course, welding is not likely to be good for the seals and lubricants within that bearing or the temper of the shaft -- 
and would be especially difficult if the arm is aluminum.  Perhaps while the machinist is working on dressing that shaft, 
he can provide a retention scheme -- like threading it for a nut. 

Note that the fan clears the front of this assembly by only a small amount, so it may be advisable to check the clearance 
of the new assembly by spinning the fan around by hand before starting the engine. 

This may start sounding like a broken record, but rather than repair the idler bearing, you might consider tossing the 
entire engine-driven fan scheme and installing an electric fan as described below. 

 

ELECTRIC FAN SUBSTITUTION FOR BELT-DRIVEN FAN:  The best solution for fan clutch problems, cracked 
fan blade problems, and idler arm problems is to install a large electric fan (or two large electric fans) and remove the 
fan, clutch, mounting assembly (shaft & bearings), belt, and idler pulley altogether -- and perhaps the little stock electric 
fan as well.  The Jag V12 is a hot beast, so the biggest electric fans that will fit should be used; a single 16”, dual 14”s, 
etc.  One benefit: we have all heard stories about how much power the belt-driven fan uses or even how much the belt 
itself uses, but the 16” electric fans typically draw about 10 amps -- meaning they use only about 1/8 horsepower when 
they are on.  And if you control them properly, they’re not on when not needed. 

There are lots of places to purchase electric fans.  Most local auto parts stores carry them, as well as J. C. Whitney 
(page 691).  Some of the best selections are from Jeg’s (page 714) or Summit Racing (page 717).  Harry Trafford points 
out there are at least two retailers on the www that specialize in electric fans: 

  Fluidyne: 

http://www.fluidyne.com/

 

  Scott's 

Fans: 

http://home.earthlink.net/~scottsfans/

 1-800-544-5596 

If you are shopping for a new fan, note that the Imperial brand electric fans are reportedly unreliable; you’d be well 
advised to avoid that make.  Ed Hyatt:  “I have had two Imperials fail and the problem was the glue that they use to 
hold the magnets to the case.  The glue fails and the magnet attaches itself to the rotor, shorting out everything and 
blowing the fuse.” 

Also note that Hayden 16” fans come in two models, one with considerably higher airflow than the other.  The high 
airflow model has comparable airflow to most other aftermarket 16” fans, but is more expensive than most.  The lower 
airflow model is comparably priced with the others, but its airflow is pathetic by comparison.  Haydens are reportedly 
very quiet, though, perhaps due to their sickle-shaped blades.  One more concern here is that the two different models 
are visually almost identical, and on store shelves it’s entirely possible that someone has switched fans around in the 
boxes in order to get the high airflow fan for the lower price -- leaving you to pay the higher price for the low airflow 
model without even knowing you’re getting gypped. 

One thing to look for in electric fans: a grille to keep your fingers out of it.  Some have it, some don’t.  If you’re the 
kind of person that worries about such things, you might want the grille.  The rest of us most definitely do not want the 
grille, since it reduces the airflow by a considerable amount. 

Peter Cohen offers another possibility:  “Went shopping in the wrecking yard the other day.  I came home with a 16" 
electric fan from an '83 Buick Regal ($20).  This fan has a ring on the outer edge that is attached to the fan blades, and 
rotates with it.  It is secured by three metal rods that go from the motor housing to two points on the lower radiator 
support brace, and one to the upper support brace.  Interestingly, it also uses a ballast resistor, and 3 wires.  One wire is 
ground, one goes through the ballast resistor, and one bypasses the ballast resistor, presumably to make a two speed 

 
 

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fan.”  This author visited his local junkyard and found similar fans in a Delta 88, a LeSabre, and a Toronado, except 
that they had plastic support structures instead of the metal tripod.  All had the same resistor arrangement for two 
speeds.  The key is apparently to look for large FWD GM cars with a transverse-mounted V6, but note that the exact 
same fan can also be found on the V6 Pontiac Fiero.  Smaller FWD GM cars have a 14” electric fan, and RWD GM 
cars use belt-driven fans.  The GM electric fans are not very compact; the total depth is around 5 inches, as compared to 
about 3 inches for a typical aftermarket electric fan, but once the stock belt-driven fan and support are removed there is 
plenty of room in the XJ-S.  Tip: take a 10mm socket and ratchet with you to the junkyard.  Note: the GM fans do not 
have a grille to keep fingers out. 

When you buy an electric fan from a reputable junkyard, they will typically mark it.  That way, you can take it home, 
test it and see if it works properly, and bring it back if it doesn’t and exchange it for another.  This is actually a better 
policy than some stores that sell new parts, since many places have a no-return policy on electrical stuff.  Needless to 
say, you are advised to test any and all electric fans as soon as you can, perhaps using jumper cables; you don’t want to 
fabricate shrouds, bracketry and wiring and then find out the fan doesn’t work. 

Electric fans can sometimes be mounted on the front of the radiator (if you can deal with the diagonal strut on the 
XJ-S), opening up considerable working room in the engine compartment.  Many aftermarket fans are designed to be 
installed on either side of the radiator; to mount in front, typically the blade must be removed, turned around, and 
reinstalled, and the wiring must be reversed to run the motor in the “blow” direction rather than the “suck” direction.  
Note that a fan on the front side and blowing should have a minimal shroud so as not to block air flowing into the 
radiator due to vehicle motion, but a fan on the back side and sucking needs a larger shroud to draw air from a large 
area of the radiator.  The shroud that’s integral with an aftermarket electric fan is usually inadequate for use on the back 
side; what’s really needed is a rectangular shroud to cover the entire radiator -- or, if multiple electric fans are used, an 
entire section of the radiator. 

Installation of electric fans requires more thought than simply slapping a fan in there.  For example, consider the space 
between the A/C condenser and the radiator: with a blower fan in front, the air might come through the condenser, go 
sideways within this space, and come back out forwards through a different part of the condenser -- providing excellent 
A/C but leaving the engine uncooled.  Similarly, a sucking fan can pull air from the engine compartment through the 
radiator backwards, across the space, and back through the radiator to the fan -- leaving the A/C condenser without 
airflow, and eventually overheating the engine from recirculating the same air over and over.  If the space between the 
condenser and radiator is open to outside, things get even worse.  In the XJ-S, one tempting possibility is to mount one 
16” electric fan in the existing shroud on the right side of the radiator (replacing the stock belt-driven fan), and a second 
16” fan on the left front of the radiator blowing through the A/C condenser; this would make sure that both coils get 
airflow.  Another possibility is to just replace the belt-driven fan with an electric and leave the small electric fan and the 
entire shroud assembly as stock. 

John Napoli went this latter route, and reports on the process:  “Removing all the stock stuff is a bit of a pain -- there is 
not much room to work, the process is iterative -- but it all comes out.  You’ll have to replace a couple of the water 
pump bolts that went through the idler pulley bracket with shorter bolts.  Remove the radiator while you are at it to 
clean out the leaves in between the rad and the condenser -- I seem to recall that if you pull the rad first it is easier to get 
out the stock fan. 

“I kept the stock electric fan and added the second inside the shroud of the old mechanical fan.  The fan shroud is split 
from the factory (little fan and big fan) so this is real easy.  I used an ‘S’ bladed fan from a Hot Rod supplier - 1-800-
strt-rod or some such - it is the largest one they had (17” or 18”).  Any fan of similar size should be fine; you can get 
them from Pep Boys or JCWhitney.  Be sure to run the fan before installing it.  Some are out of balance.  Mine was, and 
you would not believe how annoying it is!  I had to balance the blade (wrapped solder around the light spots and used 
weatherstrip adhesive to lock it in place) but it would have been better to start with a perfect unit. 

“I made brackets to hang it off of the stock shroud.  It fits in there nicely and the underhood appearance and access is 
improved.  Do not under any circumstances attach the fan to the radiator core with those silly little plastic thingies!  The 
Jag radiator is softly mounted to absorb vibration.  Use those shortcuts, and the new fan will quickly work loose. 

“Performance has been fine as measured on accurate mechanical water temperature gauges.  I like overkill, though, and 
may some day add one or two little pushers in front of the condenser.”  Note: a better way to evaluate fan adequacy 

 
 

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would be to measure the temperature of the air coming through.  A marginal capacity fan may keep the coolant within 
limits but the air coming through the radiator will be really hot, while an excessive amount of airflow will reduce how 
much the air heats up.  Of course, comparisons would have to be done on similar days with the engine running under 
similar conditions. 

This author also installed a 16” electric fan in place of the belt-driven fan, but went a slightly different route than 
Napoli.  Rather than adapting an electric fan to the opening in the existing shroud, a new section of shroud was 
fabricated.  This is remarkably easy, since the XJ-S shroud is actually two sections, with the left 1/3 containing the 
small electric fan and a set of flaps while the right 2/3 has the hole for the belt-driven fan.  By keeping the left 1/3 but 
making a new right 2/3, it was possible to provide a hole the correct diameter to fit the electric fan.  The right 2/3 piece 
of the shroud was made at a sheet metal shop by merely folding three sides of a flat piece of sheet metal, and cost $20.  
There are photos of this installation on the www at 

 

 

http://www.jag-lovers.org/xj-s/book/ElecFan.html

 

Duncan Williamson:  “I dumped the fan clutch / fan from my car and used a pair of electric fans from a Honda (I think 
it was an Integra).  They came complete with the plastic mounting frame which is the same size as an XJ-S radiator.  
The whole assembly is attached to the radiator frame with 6 large nylon ties.  I also picked up the thermostatic switch 
and soldered it into the bottom of the radiator (near the bottom hose).  I now have really good cooling in traffic and the 
whole fitting exercise took about half a day.  The fan motors are very flat so fitting/clearances were not a problem.  
They cost next to nothing, look very tidy and may well be a viable option.” 

If you are removing the stock mechanical fan bearing support, you will need two studs 4-1/4” long with 5/16”-18 
(coarse) threads on one end to continue to hold the water pump properly.  The other end of each stud can be either 
coarse or fine thread, since it gets a nut and you can use whatever nut matches.  Good luck finding such studs!  
Alternatively, you can use threaded rod cut to length, or you can cut the original stud shorter and thread it.  Or, you can 
just stack washers on the existing stud if you don’t need clearance in the area for the motor on your electric fan.  You 
will also need two 5/16”-18 bolts 1” long, but those are easy to find. 

Even though the addition of an electric fan may reduce the total hp drain on the engine, it will definitely add to the load 
on the alternator.  If you have a Lucas alternator with 66 or 75 amp capacity, this mod may push the total electrical load 
over the alternator capacity; when the A/C compressor kicks on and brings on both electric radiator fans with it, the 
system voltage drops and the lights dim.  Hence, it might prove necessary to replace the Lucas alternator with the later 
115-amp Bosch (see page 571) or a 100+ amp GM (see page 573) to maintain voltage under all operating conditions. 

 

CONTROLLING ELECTRIC FANS:  Electric fans can be controlled by either of several mechanisms.  The simplest 
method is to wire the fans to run whenever the ignition is on.  This is wasteful, however, since the fans are only needed 
when the car is standing still or moving slowly.  It also may cause the engine to run cold, or take too long to warm up, 
in cold weather. 

The electric fans could also be connected to the existing electric fan control system, which automatically operates when 
the engine is hot or when the air conditioner compressor is operating.  Note that replacing the single tiny fan with a 
couple big ones requires more electrical work than simply installing a larger fuse in the #1 position in the headlight 
fusebox; the stock wiring, even if it doesn’t burn up, will provide too much resistance and the fans won’t run as fast as 
they should.  Some suitably heavy wiring should be run from the bus on the firewall to the new fans, using a separate 
relay for each fan.  Napoli:  “I wired the new fan simply:  I added a relay that is picked up by the stock (ie, little) fan 
coming on.  The power for the new fan is routed through the relay from one of the 12 volt feeder wires located near the 
relays at the upper rear corner of the right fender.  You can get fancy and route alternative feeds from the A/C 
compressor or a dashboard switch, but if you do you may need a diode to prevent backfeeding something else.” 

Yet another possibility is to add another fan switch into the coolant system.  Jaguar makes a suitable housing for a 
switch for the Mk III E-type, C34005, that fits into a radiator hose, or maybe you could get lucky and find a switch that 
will fit one of the unused ports in the water rails on top of the heads.  Or, there are switches sold for electric fans that 
just strap to the outside of a pipe, so you could just attach it to one of the coolant pipes -- or oil pipes, for that matter.  
With any such switch, one of two fans can be connected to the stock wiring and the other to a separate switch.  This 

 
 

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would result in the two fans operating separately, and only one running when only a small amount of airflow is needed 
(since one fan will always come on before the other).  The dual circuit also provides a measure of redundancy, since 
one of the fans would provide some cooling in the event of the failure of the other circuit. 

The fans could also be controlled via an air temperature sensor in the air coming through the radiator.  This method is 
often used by the aftermarket fans, providing a switch that mounts right on the fan housing.  Note that if the fans are 
mounted in front of the radiator, the sensor must be moved to behind the radiator to work properly.  This method scares 
me, since I always wonder what would happen if there is no air coming through the radiator -- like, the car is stuck in 
traffic and there’s a slight breeze from behind. 

Yet another control system would be to provide a “paddle” switch that shuts the fans off when the airflow due to car 
motion is adequate.  There don’t appear to be any such items commercially available, but making one would not be 
difficult.  A pivot with a paddle on one side and a tiny counterweight on the other, balanced to eliminate inertia effects, 
could be installed in the area behind the front grille.  The arrangement could be rigged to operate a conventional 
microswitch with contact ratings sufficient to operate the fans directly, or a relay could be incorporated.  Using an 
ohmmeter or a light bulb, the car can be tested and the switch adjusted until it operates at a suitable speed, about 30-40 
mph.  This system would still operate the fans when the engine was cold, but would function properly with the air 
conditioner; the air conditioner requires airflow when running even when the engine is cold, but the motion of the car 
above 30 mph will be adequate; turning the fans off is OK. 

Finally, remember that you can use a combination of the above schemes; for example, you could use a paddle switch 
along with a temperature sensor to prevent the fan from operating when moving fast or when the engine is cold. 

If the control scheme used allows any possibility that the fans will be off when the car is idling, be sure to incorporate 
circuitry to run at least one fan (preferably all fans) whenever the air conditioner compressor is operating (similar to the 
present wiring for the small stock electric fan).  On some later XJ-S’s, the small stock electric fan does not come on 
with the compressor, but remember that this is assuming a belt-driven fan that is always turning; regardless of the stock 
wiring, if the belt-driven fan is removed you must provide fan operation when the A/C compressor is engaged, 
regardless of engine temperature or outdoor temperature. 

One final note: another nice feature of electric fans is their ability to run after the engine is shut off.  The biggest heat 
problem in the XJ-S is heat soak after shutdown.  The small electric fan already can provide some relief if the coolant is 
hot enough for it to be on when the car is shut down, but having multiple electric fans and multiple control schemes 
provides more possibilities for addressing this issue.  It might even make sense to provide an air temperature sensor at 
the upper rear of the engine compartment to control post-shutdown fan operation.  Or, maybe using a hot-start sensor in 
the fuel rail to control a fan would help with hot starts more than the way it’s normally used (to alter fuelling). 

 

ELECTRIC COOLING FAN:  Here we’re talking about the small OEM electric fan, not the replacements for the belt 
driven fan described above.  Yes, the original Bosch fan is atrociously expensive.  But it doesn’t do anything any other 
12V, 11” diameter electric fan won’t do; substitutions are in order.  Ideally, you’d like to include a system of rubber 
mounts, similar to the Jag originals, to minimize noise. 

One possibility is to buy the 11” electric fan from J. C. Whitney, 38xx3020A, remove the fan/motor from the shroud it 
comes in and figure out how to mount it.  Depth won’t be a problem, it’s really flat.  But you don’t really have a good 
opportunity to look at it before you buy it to decide if you can make it fit. 

John Himes says, “I am using a Hayden pancake style fan & motor.  Their 12" model fits inside of the current shroud 
for the 11" Bosch fan.  There are four mounting points on the Hayden that I had to remove.  I used a few self-tapping 
screws to secure the fan inside of the shroud.  It has been in use for three years or so with no problems.” 

If you’d rather shop at the junkyard, a Subaru fan will work with minor blade trimming and a homemade mounting 
adapter plate.  In fact, there are probably dozens of electric fans from small cars that can be used here.  Many small 
Japanese cars come with two small electric fans, one that’s standard for the car and another that comes with the air 
conditioning option -- and these two fans are different, giving you two options from the same car.