Author Topic: Use Stop Leak to fix radiator leak?  (Read 4920 times)

Offline mufflerbearing

  • Curious
  • Posts: 6
Use Stop Leak to fix radiator leak?
« on: January 12, 2018, 10:19:36 AM »
Hi all,  my 85 K100 RT has a pinhole leak in the bottom left area.  Can’t quite see it.  Appears to be near where the end cap clamps on to metallic portion.  Begins dripping as radiator/coolant heats up and pressure increases.  Before I either replace or attempt to repair it, do any of you see any problems using a stop leak product?
Thanks for any input.  Really appreciate this forum and the knowledge base out there.
  • Holly Springs NC
  • 1985 K100RT

Offline kris

  • ^ SuperNatural Motobricker
  • Posts: 584
Re: Use Stop Leak to fix radiator leak?
« Reply #1 on: January 12, 2018, 11:35:57 AM »
I used that stuff many, many years ago and I think it worked. Given that the Beemer rads are, arguably, over-sized and the Brick engine is pretty much automotive grade it's worth a shot. I don't think these "repair in a can" things are worth much over the long haul. A good rad shop might be a better solution.


Let's see what the others think.
  • In The Hammer!! Hamilton, Ontario, Canada
  • 1986 K100RT (Heinz) 2004 Kawasaki Concours (Eddy) 2007 Moto Guzzi Breva 1100 (Linda) Previous: 1968 Honda CD175 1973 Kawasaki S2350 1975 Honda CB550K
"I got bike fever bad!!"

Offline The Mighty Gryphon

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 6843
Re: Use Stop Leak to fix radiator leak?
« Reply #2 on: January 12, 2018, 12:30:26 PM »
Those leak repair in the bottle elixirs are for the crooks who need to get rid of a car with a leaky radiator.  They usually last just long enough that the guy who put it in to sell you the vehicle can say "geez, it didn't leak when you bought it".

There are a lot of good used radiators on the market.  I would get one and do it right.  With the radiator off, you can check the engine temperature sensor, clean it's terminals, and replace the fuel line to the pressure regulator.  I realize it's not a 20 minute job, but if you keep the bike, it's a job your going to be doing, probably during the best part of the riding season.  If you're lucky, it won't fail 50 miles from home.

Personally, I would replace it as a winter project.
  • 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 Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: Use Stop Leak to fix radiator leak?
« Reply #3 on: January 12, 2018, 03:22:26 PM »
+1 Gryph, the only time I would and have used them is for emergency use, to get me home. Once home the radiator was cleaned properly and repaired. If the core and fins are good on this radiator, I would take it to a reputable radiator shop and see if it could be repaired.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline stokester

  • ^ SuperNatural Motobricker
  • Posts: 847
Re: Use Stop Leak to fix radiator leak?
« Reply #4 on: January 13, 2018, 03:45:58 PM »
I'm on board with Gryph and Martin on this - fix it right by replacing or repairing the radiator.


The only stop leak product that I've seen from an OEM, albeit GM for a specific issue, is to seal engine porosity in engine components.
  • Yorktown Virginia
  • '94 K75S Dakar Yellow - '93 K75S Seiden Blau - '91 R100RT Bermuda Blue- '78 R100S Smoke Red

Offline mufflerbearing

  • Curious
  • Posts: 6
Re: Use Stop Leak to fix radiator leak?
« Reply #5 on: January 15, 2018, 02:27:31 PM »
Thanks gang,
Before I buy a used one, I think I will look into having a repair shop fix it. I’m a fan of fixing rather than replacing when able. If anyone has had a good experience with repairing, or could recommend a shop please chime in.
Thanks.
  • Holly Springs NC
  • 1985 K100RT

Offline The Mighty Gryphon

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 6843
Re: Use Stop Leak to fix radiator leak?
« Reply #6 on: January 15, 2018, 03:28:36 PM »
It's been a while, but my experience with radiator repair is that the cost is about the same as a good used radiator.  At the end of the day I feel better with an intact unit vs. a repaired one, especially with so many good used units out there. 
  • 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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