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Jaguar XJ-S Electric Radiator Fan Installation

Jaguar XJ-S

Electric Radiator Fan Installation

In the book, one suggested cure for a weak fan clutch, cracked fan blades, and/or a shot idler arm is to pitch the belt-driven fan altogether and install an electric fan in its place.  The author, Kirby Palm, did this mod, and provided the photos below.

One thing should be clarified at the outset, though.  Many have apparently gotten the impression that replacing the belt-driven fan with an electric fan is advocated as a cure for overheating problems.  No such thing.  The belt-driven fan, in good working order, provides plenty of airflow for keeping the V-12 cool; if you're tackling overheating problems, forget this page and look into other causes, notably a plugged radiator, faulty ignition timing, or vacuum leaks.  Electric fans have several advantages over belt-driven fans, including a reduced load on the engine and reduced noise, but improved cooling is not likely to be a result.  Electric fans also have the benefit that they can operate after shutdown to counteract heat soak, but the small stock electric fan on the XJ-S is adequate for this purpose.

Palm made this mod largely due to the noise issue, but note that his is not the typical situation.  First, his stock fan and clutch had been history for years, the predecessor to this electric fan was a Ford aluminum fan blade with trimmed blade tips on an aftermarket clutch.  This fan made a lot more "whoosh" than the stock plastic fan and clutch.  Second, Palm's car has a 5-speed manual transmission, so hearing the whoosh of the fan became a common irritant when shifting.

Also note that this electric fan retrofit eliminates one of the four fan belts on the XJ-S.  On most cars, the fan is mounted on the front of the water pump and tension is adjusted by moving the alternator; if the fan and clutch are removed, the water pump, alternator, and belt still must remain in place.  On the XJ-S, however, the belt-driven fan is mounted on its own bearing and support, and the belt is provided with a dedicated idler pulley on an adjustable lever.  The alternator and water pump are driven by other belts.  So, removing the belt-driven fan also permits removing its support bearing assembly in entirety, along with the idler assembly and the belt itself.  Yes, the car will get lighter; these parts that get removed weigh more than the electric fan going in.

The fan shroud on the '83 XJ-S is actually a two-piece all-metal affair, a right 2/3 attached to a left 1/3.  The left 1/3 contains a small electric fan and a set of flaps that open to allow air to blow in through the radiator but close to prevent the electric fan from sucking air from the engine compartment.  The right 2/3 has an 18" diameter opening for the 17" diameter belt-driven fan on the front of the engine (the opening must be oversize, since the engine moves around on its mounts).  The left 1/3 includes a flange along its right edge that serves as a baffle between the two fans, so either one can run by itself without simply sucking backwards through the other.

The largest electric fan commonly available is 16", and this size is commonly used by itself to cool engines of greater HP than the Jag V12.  Coupled with the smaller stock fan, such a setup should provide more than enough airflow -- provided there are no "leaks" in the air path that allow airflow drawn by the fans to bypass the radiator, oil cooler or A/C condensor.  Unfortunately, Palm found a bunch of such leaks, so plugging such openings should be part of any cooling system renovation.

While some have opted to mount an electric fan within the opening in the stock shroud, Palm opted to fabricate a new right 2/3.  This cost $20 at a local sheet metal shop, and took all of five minutes; just hand the guy the stock shroud and explain that all you want is a flat piece of sheet metal folded down on three sides to fit right where the stock shroud did.  Making the hole for the fan itself was left for later, so that it could be located to maximize clearances if necessary; once marked, it was easily cut with a jigsaw.

The fan used here was purchased at the local junkyard for $20 and the few minutes' effort it took to remove it from the car it was in -- an Olds Toronado of the later transverse V6 persuasion.  Several GM FWD transverse V6 cars were found to share essentially the exact same fan, including Delta 88's, Regals, and LeSabres; there were differences in the plastic shroud, but the motors and fan blades were identical.  Peter Cohen found a Regal with a 3-legged metal support, not unlike the one on the stock smaller fan on the XJ-S.  Late model Camaros/Firebirds and Corvettes reportedly also share this same 16" fan, apparently because they have sloped radiators..

If you choose to go the junkyard route, a tip: take a small ratchet, extension, and 10mm socket with you.  Also note:  There are lots of 14" electric fans on GM FWD cars, and they are visually remarkably similar; take along a measuring tape to make sure you're looking at a 16" before removing it.

These cars also come with a 2-speed control on the fan, with a resistor pack attached to one of the struts, but this was abandoned for Palm's XJ-S.  You could, obviously, decide to make use of the resistor pack and devise a way to make the fan run at low speed whenever the car is warmed up and kick into high speed only when really needed, or some such.

First, a couple of pictures of the new right 2/3 shroud with the Toronado shroud and motor installed, but the blade removed.  The engine side:

Obviously, the plastic GM shroud must be trimmed; since it is a three-dimensional device that forms a rectangular box covering the back side of a radiator, a considerable amount must be cut off to leave a simple flat surface that can be attached to the flat sheet metal.  It cuts easily enough with stout sheet metal shears or a jigsaw or hacksaw.  Since the shroud was not flat in a couple of places immediately adjacent to the fan itself, making a round circle was not possible.  You also don't have a choice of which way to orient the shroud, since the motor itself is non-watertight and has a distinct downward side and must be mounted correctly or it might collect rainwater; the plug on the motor must be at the bottom.  All in all, it might have been possible to cut the shroud to make it prettier than it is, but Palm doesn't care too much about such things.

While in the junkyard, you might as well get the 2-terminal connector too, although a pair of normal spade connectors will also work.  One of those two terminals is for a ground connection, necessary since the support is plastic and won't conduct electricity.

By the way, the only other significant cost was the control, an Imperial air temp fan control from Discount Auto Parts for about $17.  Hence, although there obviously has been some work involved, the total parts cost for this installation was considerably less than the cost of either a replacement Jaguar fan clutch, the stock fan blade, or the idler arm by itself.

Note that the GM electric fan is not very compact or "flat"; in fact, it protrudes rearward about 4" from the surface of the shroud, as well as about 1" forward (right up close to the back side of the radiator).  Fortunately, there is plenty of room in the XJ-S once the stock fan support is removed.  However, if you prefer, you can buy an aftermarket 16" fan such as those offered by  Summit RacingFluidyne, or Scott's Fans; typically these are a lot flatter, around 3" total depth, leaving considerably more empty space in the engine compartment.  It'll probably look prettier, too.

Reportedly, another option is to find a V6 Pontiac Fiero in the junkyard, which comes with a 16" fan with a flat motor.

The radiator side:

Now, with the fan blade installed and connected together with the left 1/3 shroud, engine side:

Obviously, the wires from the small fan have yet to be strapped down to one of the struts.  The plug for the larger fan will need to be connected and those wires strapped down as well.

The junkyard writes their name and the date on fans when you pay for them.  This is so you can bring it back if it doesn't work.  Yes, that's correct, you can return defective electrical items at a junkyard, something you often cannot do when you buy new electrical parts.  In fact, in connection with a similar retrofit on another Jag, one of these 16" GM fans was found to be NFG and was returned and exchanged for another with no problem.

The GM 16" fan is very quiet, thanks partly to the unequally-spaced blades -- a common trick to eliminate resonances.  The integral tip shroud, despite being plastic, still provides considerable flywheel effect, and this fan seems to spin forever after the power is shut off.

Radiator side:

The shroud assembly is held in place by tabs such as those that are visible on the original 1/3 section in the pictures.  After these pictures were taken, similar tabs were easily fabbed up and attached to the new 2/3 section with pop rivets.

That smaller fan probably could use some explanation, as well.  The original Bosch motor exploded, and a replacement costs a fortune.  A Subaru fan was used for years, then it went bad as well.  The fan in the picture is from a Mercedes, and cost another $20 at the same junkyard.  It is a considerably heavier-duty item than the original Bosch -- in fact, it appears to be a heavier-duty item than the motor on the 16" fan!  It fits perfectly in the opening in the stock left 1/3, but a circular adapter plate had to be fabricated to adapt it to the 3-legged mount.  Since the motor, complete with adapter plate, is still flatter than the Bosch assembly was, the threaded ends on the 3-legged mount were tapped farther down the legs, the nuts threaded on farther to move the motor forward into the shroud, and the tips of the three legs trimmed off to keep them from poking into the radiator.  All of that may have been unnecessary, since it might have worked just fine mounted farther rearward, but while the shroud is on the bench and convenient to work on is the best time to optimize the fit.

If you're in the junkyard, picking up a Mercedes fan is easy.  It's a puller fan, but it's mounted in a pusher position in front of the radiator and supported by three cross braces.  Open the hood and the grille goes up with the hood, the fan is right there staring at you.  That 10mm socket and ratchet will have it off in a minute, and you'll need a pair of clippers to cut the wires. Sorry, it's not known exactly what model Mercedes this was, but the impression is that lots of Mercedes sedans have similar fans.


Now, on to other installations.  Alan Heartfield installed a 16" GM fan similar to that used on Palm's car except that the support was a little different (there are lots of different support schemes used in GM cars to hold the exact same motor and fan blade).  However, rather than fabricating a new shroud, Heartfield fit the shroud on the GM fan into the existing shroud on the XJ-S.

In that last picture, you can see two items installed in the upper right radiator hose.  The rearward one is a Gano filter.  The forward one is a tee and sensor from a 1982 Saab 900 Turbo to turn the electric fan on and off via a relay.

Note that installing a switch in the upper hose this way will result in the electric fan remaining off until the engine warms up, then coming on and staying on.  Some people prefer this operation to the on/off cycling of most electric fan installations.  However, if you'd rather the fan cycled off when not needed, you will need to install a temp switch in the outlet header tank on the radiator, the lower radiator hose, or the water pump inlet -- just like the existing switch for the small electric fan.


Peyton Gill installed an aftermarket Hayden fan within the OEM shroud:

Unfortunately, Gill reports that the results are less than satisfactory; the car does not remain as cool as he'd like when stuck in traffic in Atlanta (if you're in Atlanta, you're stuck in traffic!) on a hot summer day.  With the fan running, moving your hand around behind it reveals that it isn't moving much air (Palm's installation creates a hurricane under there!).  It's unknown whether this is because this particular model electric fan is lame, that ultra-fine finger guard is too restrictive, there are obstructions in front of the radiator, or some other problem.  "It is a Hayden 16 inch.  Part # 3700.  There is a 3710 which is 16 inch but higher CFM.  Found out this fact a little too late."

Gill also had problems with the relay that came with this fan.

Until it is determined what type fans really move air, it might be advisable to insist upon only the highest-flow 16" fans available -- or, better yet, just get the GM fan from a junkyard.  It's cheap, and you know it moves plenty of air not only because Palm says so but also because GM uses it to keep their cars cool.

To see some pictures of another electric fan installation in an XJ-S, visit  Mark Stoner's web site.

Duncan Williamson says, "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 fans' motors are very flat so fitting/clearances were not a problem.  They cost next to nothing, and look very tidy..."  Note that Honda introduced a separate line of cars called Acura in the US, but in NZ they receive the same cars -- still called Integras and Legends -- as used cars from Japan, where they are simply called Hondas.
 
 

 

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