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Fan fuse - Long

This is long but informative to anyone who needs to put in a radiator
fan fuse.  I got it from Len, who got it from Dewitt.

> **********************************************************************
> *******
> Gary M. Lewis
> 1986 5000   CS Turbo 5 Speed   195,000 miles (and counting...)
> **********************************************************************
> *******
> Cooling Fan Fuse - A Type 44 Wiring Upgrade 
> Cooling Fan Fuse Modification
> In addition to their many excellent qualities,
> the 5kt/q (type 44) cars are well known for their
> tendency to incinerate the left main engine
> compartment wiring harness when the cooling fan
> seizes. There is usually a warning squeak from
> the fan bearings giving the owner between 2 hours
> and 2 months advance notice of impending doom.
> See the past "Audi Bonfires" thread, for example.
> There have been several solutions presented on the
> list, but I feel the most thoroughly engineered fix
> has been one designed by Audi. A neatly housed
> and mounted 80A fusible link was incorporated
> into the USA 200s at some point(?). I first noticed
> this fix in a 1991 200q. Fortunately, this modifi-
> cation is as easy as pie for any type 44.
> The parts list: (Audi P/Ns are given for the
> hardware, but you can always eyeball this and
> use whatever you sweep up off the garage floor.
> I ordered this stuff from Carlsen when I bought
> the box, bracket and fuse; for the extra $2, you
> can get it exactly right. BTW, your Carlsen
> prices should be lower than Retail.)
> Qty. Item  Audi P/N Retail $
> - -------------------------------------------------
> 1 fuse box 281 937 505 A 10.89
> 1 bracket  443 971 845 AM  9.55
> 1 fuse link, 80A N 017 125 3  1.30
> 2 screw, M5x8 N 014 128 11  0.45
> 2 lock washer N 012 005 3  0.15
> 2 screw, tapping N 013 966 26  0.38
> 2 washer, flat N 011 556 2  0.15
> Other materials:
> 1 foot 10 AWG wire for automotive service, preferably
>         brown to match the European color convention.
> 2 crimp terminals, 10-12 AWG (yel.), #10 ring
> 1 crimp terminal, 10-12 AWG (yel.), 1/4" ring
> 3-4" shrink tubing, 1/4" to 3/8" diam. (optional
>         for insulated crimp terminals)
> 1 or 2  cable ties (optional)
> Tools: 10mm wrench, medium Phillips screw driver,
>        high quality crimping tool appropriate to selected
>        terminals (perhaps borrowed), heat gun, wire
>        stripper.
> Procedure:
> Notes.
> a. It is proper to disconnect the battery before undertaking
> any wiring modifications. However, if the engine is
> STONE COLD and if you email me a signed liability waver
> in advance, it is possible to proceed with reckless
> disregard for safety and leave the battery connected
> since the effected wiring is strictly ground side.
> Keep the wrench away from the positive fan motor terminal
> and your face clear of the fan blades just in case I'm a
> lying dog.
> b. It is assumed that you know how to properly fit
> crimped wire terminals and have the proper tool.
> Soldered joints can be used but are emphatically
> not recommended for automotive wiring connections
> for the best long term reliability. However, if you don't have
> access to a _good_ crimping tool, soldering may be the
> better choice. A cheap, single acting "electrician's"
> crimper will definitely not provide sufficient pressure
> to correctly crimp such heavy terminals. (I'm not interested
> in a crimp vs. solder or crimp vs. solder & crimp thread.
> Just suit yourself and take your best shot.)
> c. The fuse link box has two link positions. This fan
> motor circuit only uses one of them. Please don't swoon
> and hurt yourself while contemplating the infinite
> possibilities.
> d.  I haven't looked at every type 44 model. Details
> could certainly vary. Determine if the following
> instructions make sense for your vehicle before starting
> so you will have been able to work out any necessary
> corrections ahead of time. Easiest to do with parts
> in hand.
> 1. Establish that the shrink tubing, if used, is sized
>    to fit the selected crimp terminals. Mandatory for
>    uninsulated terminals.
> 2. Mount fuse box to fuse bracket with tapping screws
>    and flat washers. (I suggest mounting so that
>    the hinge of the cover is up^ in order to better
>    resist water entry. It would be a good idea to
>    test fit the bracket in the car first just so
>    that it is completely obvious which end
>    will be "up" and that the bracket's mounting
>    tab or ear bends away from the surface the box
>    is attached to.)
> 3. Remove the right-rear mounting screw from coolant
>    reservoir. This screw also retains a mounting
>    clip for the left-front ABS sensor connector
>    and a small aluminum wiring harness support "Z"
>    bracket.
> 4. Remove this aluminum "Z" bracket (for ABS unit
>    wiring harness) after releasing the plastic wire
>    clip from "Z" bracket hole. Leave plastic clip on
>    harness. Throw "Z" bracket into the "save for use
>    in next lifetime" bin.
> 5. Mount bracket/fuse box. The stacking order is new
>    fuse box bracket, then ABS connector clip, then
>    coolant reservoir tab. This all goes together
>    nicely like bread and butter. The fuse box
>    now faces the engine.
> 6. Leave the dangling ABS wiring clip unattached
>    until the wiring is complete. Be comforted
>    by the fact that the new fuse box bracket has
>    a hole just the right size and in just the right
>    place to accept the clip nibs. (Ya just gotta
>    love German engineers at times like this.)
> 7. Remove the cooling fan motor's ground lead (single
>    heavy brown wire).
> 8. Cut off (oh go ahead) the terminal on this lead
>    since it ought to be replaced by a smaller size
>    ring to match the fuse box screw size. You shade
>    tree electricians might spit at this but I really
>    think it necessary for a good installation. Cut
>    the wire as close to the terminal as possible to
>    allow good reach with the remainder.
> 9. Install a #10 ring terminal (metric size 5 mm?)
>    on this fan motor ground lead. Slip a piece of
>    shrink tubing on beforehand to avoid that stupid
>    feeling. Carefully apply shrinking heat.
> 10.Bend the ground wire back toward the new fuse box and
>    loosely connect this terminal to one of the forward-most
>    box screw terminals. Use a 5Mx8 screw and a lock
>    washer. The finished stack will be link, ring terminal,
>    lock washer. (The fusible link, itself, can be
>    easily dropped into position under the ring terminals
>    after all the wires are in place.)
> 11.Make up a 10 AWG connecting wire with a #10 ring
>    terminal at one end and a 1/4" ring at the other.
>    You should test fit this in the car. In my case,
>    11 1/2" from ring center to ring center allowed a
>    nice neat loop from a rear fuse box screw terminal
>    to the fan motor along side the ABS unit harness,
>    including routing through the aforementioned plastic
>    wiring clip. Again, plan ahead as needed for shrink
>    tubing.
> 12.Route the new wire from the rear fuse box terminal,
>    which opposes, front-to-rear, the one you've used for
>    the original fan motor ground wire, forward along the
>    ABS unit harness, through the wire clip and down to
>    the fan motor's ground terminal.
> 13.Drop the 80A fusible link into place under the ring
>    terminals, snug down the screws, coat the connections
>    with battery terminal sealant or similar and snap the box
>    cover shut. (The box is not weather tight but is well
>    located considering it's under the hood. A little anti-
>    corrosion protection would be a good idea.)
> 14.Finalize the wiring dress and snap the wire clip
>    into the bracket hole. Use a cable tie or 2 if you
>    like. I found this not particularly necessary due to
>    the existing clip, the short run and the stiffness of
>    the 10 AWG wire.
> 15.Step back and admire your official factory upgrade.
> 16.Sleep at night.
> Have fun and best luck,
> DeWitt Harrison   de@aztek-eng.com
> Dewit was the original poster
> Boulder, CO
> 87 5CSTQ - 113,000
> A great car, a great hobby!