To report back my results, after removing the fan shroud and cleaning up the threads, the fan clutch nut went right on using the cn90 patented rawhide string method!
It took something like less than 30 seconds this time!
Here's the (text for now) DIY:
REMOVE SHROUD:
(Reference:
http://www.beisansystems.com/procedures/e39_fan_procedure.htm )
- Raise the E39 with a jack and put on jack stands (or ramps)
- Remove the under-engine shroud pan (nine #2 Phillips one-twist bolts)
- Draw the hose sequence or snap photos of the underside shroud hose routing.
- Protect your eyes from falling dust with goggles (I didn't and wished I did).
- Locate the auxiliary pump at the bottom driver-side corner of the shroud.
- Disconnect the press-pull auxiliary coolant pump electrical connector
- Slide the auxiliary pump toward the center of the radiator out of the
fan shroud sleeve by lining up the hose in the clamp and tugging gently
- From above, follow the smaller of the two power steering hoses down
until you reach a hose-to-hose clip shared with one of the radiator
hoses; disconnect the radiator hose side of this clip and make a note
of the location of the clip as it will move once you disconnect it.
- From below, for the upper of the two expansion tank hoses only,
working your way from the passengers side to the drivers side,
disconnect the three clips at the bottom of the fan shroud; then
disconnect the one clip at the back of the fan shroud facing the engine.
- From below, for the lower of the two expansion tank hoses, working
your way from the passenger side to the drivers side, disconnect
the three clips on the bottom of the fan shroud and then disconnect
the one clip on the side of the fan shroud.
- Mark with whiteout or nail polish or chalk where the clips line up
with the hoses once the hoses are out (you'll see the indentations).
Later you'll use these marks for reference or you'll transfer these
marks to the new hoses in the same position.
- From above, follow the wire out of the auxiliary water pump to the
AUC (stink) Automatic Air Recirculation sensor on the driver's side in
front of the alternator
just under the upper radiator hose elbow. Notice the orientation of
this AUC sensor (electrical connector up, embossed lettering outward).
You'll need that information for reassembly.
- Press the plastic clip on the stink sensor connector and pull up to
remove the AUC sensor from the fan shroud.
- Remove the diabolically German 2-inch by 3-inch AUC sensor housing
by wiggling and coercing it, mostly pushing up from the bottom of
the AUC sensor housing and pulling the top of the AUC sensor housing
away from the shroud. Then, once it's a bit loose, switch directions
of force by pushing down on the AUC sensor housing, pulling the bottom
of the AUC sensor housing away from the shroud. You have to just do it.
- Place the AUC sensor housing in your parts bin.
- With a 3/16th flathead screwdriver pry out (only) the (center)
plastic rivet pin on the driver's side of the shroud near the upper
hose until you can get needle nose pliers on it to pull that center
pin out. Then pry out the base surrounding the center pin.
- Likewise, remove the rivet to the side of the expansion tank.
- Temporarily remove the expansion tank filler cap.
- With two screwdrivers, pry up the escutcheon around the bleeder screw
next to the expansion tank filler cap (that has the words ENTLUFTUNG
molded into the top) and remove the escutcheon.
- Replace the expansion tank filler cap.
- Study how the M-shaped rubber seal at the top of the fan shroud sits.
- Pull up on the two-foot long M-shaped seal at the top of the fan shroud.
- Lift the fan shroud up and to the rear of the car; you'll get about 4
inches of room to see the small hose that goes across from the expansion
tank to a nipple on the drivers side.
- BE VERY CAREFUL IN THE NEXT STEP (I broke the nipple right off!)
- The Beisan DIY tells you to pry open the original clamp next to the nipple
on the driver's side, so that you can remove the hose. I disagree. You do
not want to put ANY pressure on that brittle nipple. If you must remove
the factory clamp, dremel it off at the point ABOVE the hoses. Better
yet, leave the factory clamp on & remove the entire nipple (gently).
- The nipple often snaps in half right at the edge of the groove for
the o-ring. In addition the groove for the o-ring molded in has sharp
corners rather than a rounded groove, further weakening the part such that
it often snaps when working around it. Some report removing the old nipple
with a 10mm socket pushed into the upper radiator hose opening, and pushed
it on to the "clipped" end to push it closed enough so that it can be pried
out of the radiator (putting a string on the socket in case it fell into
the radiator).
http://bimmerfest.com/forums/showpost.php?p=1943285&postcount=16
- Remove the fan clutch nut (see separate instructions) with 32mm fan clutch
nut wrench (1 1/4") and 48-mm hole spacing fan hub bolt counterhold tool.
- Lift fan shroud and pull fan out toward driver tilting and wiggling
as necessary to get the fan out of the shroud; it will come out aiming
at the driver's steering wheel.
- Beisan says to remove the fan shroud from the engine bay at this point
but I don't see how you can with the expansion tank, it's three hoses,
and the electrical connector on the bottom still connected to the
expansion tank.
- Temporarily remove expansion tank bleed screw with a P3 Phillips screwdriver.
- Take a good long hard look at how the expansion tank hoses snap into
the shroud at the bottom of the expansion tank (you'll need that later
when you put them back).
- Dislodge the expansion tank from the fan shroud by pulling the top
toward the windshield about a half inch away from the top of the fan
shroud; dislodge the two hoses at the bottom from the fan shroud.
- Replace the bleed screw with a P3 Phillips screwdriver.
- Pull the drivers side of the fan shroud up and at the same time pull
the bottom hoses of the expansion tank away from the fan shroud.
- Pull the upper expansion tank house through the tunnel in the
fan so that it is not impeding removal of the fan shroud
- Finally, remove the shroud from the engine bay, leaving the expansion
tank still connected to the car.
- Disconnect the frail-looking electrical connector from the bottom of
the expansion tank.
- The Beisans say to place the expansion tank at a high location in the
engine bay but that only made my broken nipple leak more so I put it
at about the same level it was prior.
- As per the Beisans, I tried to keep the expansion tank overflow hose
high to keep coolant from draining out but whenever I raised the expansion
tank, coolant drained out of the broken nipple on the radiator anyway.
Eventually, while I was working on putting the fan on the water
pump, the expansion tank fell to the floor with a full thud, and
I had to jam a branch of wood from my plants into the broken nipple
end on the end of the hose to stave the bleeding mess.
- At this point, the fan is off, the shroud is off, and the expansion
tank is connected but lying on the ground.
- Voila! I have access now to the water pump bolt!
REPLACE SHROUD:
Make sure your original belt diagram is handy (you'll refer to it a lot!).
- Put the altnerator/ps/wp serpentine belt back on as before, this time
using the pin to keep tension off the belt while your fingers are in there.
If there's any slack, you put it on wrong (ask me how I know).
Again, the original paper diagram is invaluable!
- When the alt/ps/wp belt is as aligned as you can get it with the set pin
in the upper tensioner, only then should you remove the set pin and align
the last inch of the belt on the pulleys just right by turning clockwise
with the 16mm socket wrench on the alt/psp/wp mechanical tensioner.
- Clean the expansion tank coolant temperature sensor electrical connector
with MAF sensor cleaner (xylene) and when dry, add a dab of dialectric grease.
- Reconnect the expansion tank coolant temperature sensor connector but don't
make the mistake I made which was to connect with the wires above the ac
hose; the wires must be below the ac hose.
- Rethread the expansion tank overflow hose through the top of the fan shroud
- Reconnect the nipple and pipe clamp. Don't make the mistake I did, thinking I could leave this for later because as soon as I removed the bleed screw in the expansion tank, fluid leaked out of the radiator hole due to the expansion tank being above that hole. When you press the nipple down into the radiator, make sure it goes all the way until the seam is small (I used a soft rubber mallet).
- Make sure the hose-clamp bolt is at south position, closest to the radiator and furthest from the fan shroud. I used a 7mm quarter-inch socket for security when tightening.
-. Place the shroud approximately in place with the drivers side up about six inches higher and replace the expansion tank hoses (I struggled for half an hour trying to get the two hoses in the bottom of the expansion tank to snap back into place). Finally I re-removed the bleeder screw, tilted the expansion tank about 1/2 inch at the top away from the fan shroud, and snap, the bottom hoses snapped into place instantly. Lesson learned.
-. Replace the bleeder screw using a P3 Phillips screwdriver.
-. Tape and wrap about 2 feet of rawhide on the fan nut.
-. Place fan clutch assembly inside the fan shroud.
-. Position fan shroud as close to perfect on the top and put on eye protection and then go down underneath the car to move hoses about and position the fan shroud back in the two (2) plastic clips at the bottom and one in each bottom corner (2). There is a clip on the sides (2), about a third of the way up, and a clip near the top on the sides (2) for a total of about 8 clips.
-. Unfortunately for me, my carful taping of the fan clutch fell off when I tried to keep the heavy fan out of my way by tying it to the car. Lesson learned. Don't try that.
-. Retaping the rawhide on from the driver's side (there is no access on the passenger side of the fan shroud due to the fact the expansion tank is now firmly in) and wrapping it around the fan clutch nut, it was easy to spin the fan on straight; took less than a minute to get the fan nut spun onto five or six threads until it almost bottomed on the shoulder of the water pump shaft.
-. When the string falls off, tighten the nut (counter clockwise) by holding the fan with your left hand and turning the 32 mm wrench counter clockwise (the water pump hub won't spin due to belt tension). After about 10, fifteen degree twists of the 32mm wrench, you'll feel the nut tighten and the water pump hub will finally move.
-. Bringing the 45-mm hole spacing counterhold tool from the driver's side, UNDER the upper hose (it won't work any other way), twist the fan hub with the 32mm wrench until the right set of holes seats in the hole and slot of the counterhold tool. Tighten as desired. (Personally, I couldn't get more than a couple of degrees of movement.)
-. Nudge the fan shroud into its final seating position, taking care to inspect the two rivet holes at top (2), the clips on the bottom third on the side (2), the clips at each bottom corner (2) and the two clips on the bottom (2) for a total of 8 clips.
-. The top should be aligned so that you can replace the two-foot long rubber M-shaped seal at the top of the fan shroud. Press along the entire lenght of both channels of the M-shaped seal to confirm proper positioning.
-. Temporarily remove the expansion tank filler cap.
-. Align the two clips and the word ENTLUFTUNG for the escutcheon that goes around the bleeder screw next to the expansion tank filler cap. and snap into place by wiggling the expansion tand and fan shroud as you press down on the excutcheon.
-. Replace expansion tank filler cap.
-. From above, replace the plastic rivets at each corner of the shroud.
-. Pick up the AUC sensor housing out of your parts box and locate the holes in the fan shroud just below the upper radiator hose elbow where it snaps into place on the fan shroud.
-. Orient the diabolically German 2-inch by 3-inch automatic air recirculation AUC sensor housing with the electrical connector facing upwards and the embossed letters facing to the driver's side outside of the car. Notice the hooks at the top of the housing face down and the hooks on the bottom face up, while the flap at the very bottom opens horizontally. Place the two bottom hooks in first, then lift up while pressing in so that you can place the top hooks next. The bottom flap should land over the bottom shelf of the fan shroud connection point. At this point, I noticed my bottom shelf was broken, probably when I manhandled the AUC out the first time.
- Place a dab of dialectric grease in the electrical connector for the AUC and connect the AUC sensor wiring connector making sure to keep the wires below the upper radiator hose elbow.
- From above, locate the electrical connector for the auxiliary pump and place a dab of dialectric grease on the connector before feeding it down dangling to where you can reach it below.
- From underneath, align the auxiliary pump with its holder on the fan shroud and slide in from the center toward the drivers side until the marks you made prior on the hose align with the clips on the fan shroud.
- Press the electrical connector for the auxiliary fan onto the auxiliary fan until you hear it click tight.
- From above, follow the smaller of the two lines eminating from the bottom of the power steering reservoir to the hose-to-hose clip for the lower expansion tank hose and connect the two hoses together at the point noted before you originally removed this clip.
- From below, for the lower expansion tank hose only, working your way from the drivers side to the passenger side, connect the clip on the side of the fan shroud; and lastly connect the three clips at the bottom of the fan shroud.
- From below, for the upper of the two expansion tank hoses only, working your way from the drivers side to the passenger side, connect the clip on the edge of the fan shroud facing the engine; and then connect the three clips at the bottom of the fan shroud.
- Voila! The fan shroud is now reattached.