Re: [xj-s] troubleshoot an suspect fan clutch

[sean.straw+Jaguar@mail.professional.org (Sean Straw)]

At 12:19 06-07-98 -0700, George Harris wrote:
>Is there a definitive way of troubleshooting a bad fan clutch?

This isn't definitive or official, but it is what I do:

Presumably you're trying to diagnose while it is still installed.

NOTE: If your fan blade is yellow (official Jaguar colour code GWT "grimy
white") care should be exercised when trying to turn it - it may be brittle
(mine was in great shape, but I replaced it with the newer black model ($)
anyway when I replaced my clutch just last weekend).

While the vehicle is cool (engine not running, not warm to the touch),
grasp the fan and see if you can turn it.  First thing in the morning, or
late at night is a good time so you can rule out ambient temperatures.  It
should rotate _fairly_ freely on the pulley.  By fairly, I mean that there
is still some "grab" from the bearings and what-not, but that it turns easy
enough with a single finger and doesn't require much force.  You might
actually want to run the motor a minute or two (just to spin it, not to
warm it up) to ensure that the bearings are running free by raising the
viscocity of the grease in the bearings and the oil in the clutch.

If the fan spins, then the fan is at least free when it should be.  Next,
run the engine warm (let the temp gauge reach N).  You should be able to
HEAR the fan pulling air (resistance) even with the bonnet closed.  Pop the
bonnet, and shut off the engine.  The fan will still spin somewhat
manually, but with considerably more resistance than when it was cool in
the first test.

If either of these two tests fail, then you either have a clutch that is
siezed (I had a shot bearing seal on mine, and it caused the bearings to
run dry - injecting a bit of bearing grease suitable for wheel bearings
kept it running well enough until I replaced it), or not engaging (and
therefore not cooling at idle speeds).

You might find that you can spin it one direction (I'll say counter
clockwise from the driver's perspective), but not in the other (clockwise,
same perspective).  This would be indicative of bearing failure in the clutch.

Repair: not likely.  I'd like to find a replacement bearing set and seal
for my original, if only to salvage the otherwise fine part, but I'm not
holding out for ever finding one.

Replacement:  Official Jaguar part, from Jaguar Dealer, was either US$117
or $177 (damn - I ordered the fan blade and the clutch at the same time,
can't remember which was which price, though I believe the clutch was oddly
the cheaper of the two).  DO NOT bother with installing a salvaged part -
go new - it isn't worth the bother of having to install another sometime
sooner when the salvage part eventually wears out.  It isn't that I'm
against salvage parts - just for some things, it doesn't make sense.

---                             <http://jaguar.professional.org/>
Sean Straw                      '88 Jaguar XJSC 5.3L V12
Marin County, California        '69 Buick GranSport 455 V8

---

References:

• [xj-s] troubleshoot an suspect fan clutch
• From: "George Harris" <ontheroad33@hotmail.com>

---

• Prev by Date: Fw: [xj-s] troubleshoot an suspect fan clutch
• Next by Date: [xj-s] Heater Pipes
• Prev by thread: [xj-s] troubleshoot an suspect fan clutch
• Next by thread: [xj-s] Header Tank
• Index(es):
  • Main
  • Thread