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Author Topic: Wonky Turn Signals  (Read 2822 times)

Offline The Mighty Gryphon

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 6843
Wonky Turn Signals
« on: December 10, 2020, 07:47:59 PM »
Posting this in the hope that someone in the future will find it useful.

Couple weeks ago after a long ride I noticed that the turn signals on my 1991 K100RS 16V weren't working properly.  Pushing the paddle for the signal lit up the signal and the bulb in the instrument cluster, but the signal wouldn't flash and the signals went out as soon as the paddle was released. 

The four way emergency flashers still worked properly but the horn didn't.  Swapping for a good flasher module didn't help.  Some troubleshooting indicated the problem was a blown fuse #7.  Replacing the fuse got things working properly again, but a few weeks later the fuse blew again.

Turns out the problem was bad fan bearings!  The bearings forced the fan motor to draw more current causing the fuses to blow as well as melting the motor's plastic brush holders. 

Just ordered a Spal #30100402 fan to replace the melted one.

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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"
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Offline Ctrogstad

  • Curious
  • Posts: 2
Re: Wonky Turn Signals
« Reply #1 on: January 01, 2021, 10:20:43 AM »
Nice detective work.
What led you from the turn signal and fuse down to the fan?
Tks
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  • In pieces all over the garage
  • 87 K75

Offline The Mighty Gryphon

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 6843
Re: Wonky Turn Signals
« Reply #2 on: January 01, 2021, 10:48:56 AM »
When I checked the fuses #7 was blown and when I replaced it the signals worked. 

When it blew a few weeks later I decided to see what else was on fuse #7 besides the turn signals.  Turns out the fan is also on that fuse. 

I had a fan problem a few years ago on another K100 like it so that was the first thing I suspected.  I disconnected the fan plug under the tank and put 12v directly on it and nothing happened.  That confirmed the melted brush holders.  Those Bosch fans are total crap.  The Spal was something I thought about doing when I first got that bike, but the fan looked pretty good.  That was only 2 years and about 8,000 miles ago.
Logged
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline stokester

  • ^ SuperNatural Motobricker
  • Posts: 847
Re: Wonky Turn Signals
« Reply #3 on: January 01, 2021, 10:04:01 PM »
Great info, thanks for sharing.
I'm a "lead turn" guy when it comes to replacing components unless they beat me to the punch so I have replaced the fan on my 75k mile K75S that showed no indication of problems.  Upon removal I found it squeaked when rotated and replaced it with a Spal kit from tills.de. No worries from here.
Next is to start carrying a fuel pump.
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  • Yorktown Virginia
  • '94 K75S Dakar Yellow - '93 K75S Seiden Blau - '91 R100RT Bermuda Blue- '78 R100S Smoke Red

Offline The Mighty Gryphon

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 6843
Re: Wonky Turn Signals
« Reply #4 on: January 02, 2021, 09:53:50 AM »
Yeah, this one caught me by surprise, the bike only has 42k miles on it.  Strange, it's only been my 16 valve K's that have had the fan fail.  The two K75's and the '88 K100 have been okay.  Even the K75 with 94k on it hasn't had any fan problems. Yet!  It's probably time to do the preventative Spal retrofit.
Logged
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline alabrew

  • ^ Proficient Motobricker
  • Posts: 288
Re: Wonky Turn Signals
« Reply #5 on: January 02, 2021, 03:32:46 PM »
Big Red "lost" her's at 20k, just 35 yrs old.   :laughing4-giggles:
Logged
  • Birmingham, Alabama
  • 1985 K100, 1991 K100RS
Also:
2005 K1200LT
1979 R65
200,000 miles on BMW motorcycles
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