Re: Radiator Fan Motor: Thanks

["Fred Munro" <munrof@isys.ca>]

-----Original Message-----
From: Sandy Duffy <sandyduffy@home.com>
To: quattro@coimbra.ans.net <quattro@coimbra.ans.net>
Cc: Gary.Lewis@West.Boeing.com <Gary.Lewis@West.Boeing.com>
Date: Friday, April 24, 1998 6:43 PM
Subject: RE: Radiator Fan Motor: Thanks


>You wrote:
>>My decision:
>>7 blade upgrade from The Parts Connection - $167 w/tax delivered.  And
>>Al Powell and I were earlier discussing the fuse thing.  I am going to
>>put a 60 amp fuse on the ground side of the fan motor wires.
>>
>Gary:
>
>Great idea.  IMHO the fuse should be more like 70 amps.  According to my
>Bentley, the fan in a "stage three" cooling event draws 500 watts...thats
>42 amps!  Assuming a starting current of 60 amps to get it turning & up to
>speed, 70 amps should probably be the fuse value.  Also If you have a fuse,
>you might want to put a medium duty 12 volt light bulb across the fuse that
>will glow very brightly if the fuse blows so that you know you've got a
>problem!  I think the original reason for NOT installing a fuse was that
>wiring harnesses are much less expensive than new engines.  (If that fan
>fails to turn you get one seriously overheated/toast of an engine!)
>
>HTH
>
>Sandy

    My '91 200q has a fuse in the radiator fan circuit. It is an 80A strap
fuse in the GROUND circuit of all places. Found it a couple of years ago
when it corroded off.
    I don't know if the '86 5k's also have fused grounds but you may want to
check before installing another fuse in the power lead.
    BTW, when the fuse fails, the temp gauge and Autocheck circuit gives
ample warning of overheating.

HTH

Fred Munro
'91 200q  250k km