BMW K bikes (Bricks)


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robmack

robmack
Life time member
Life time member
BMW uses a red colored o-ring to seal the interface between the engine block and the inlet pipe (part #18 in the diagram below)  but I'm not sure of the material composition of this oring.  For example, it's possible that the o-rings are Viton.

Can normal Buna-N oring be used in cooling system? 128


 have a metric oring selection kit with many sizes of black Buna-N o-rings. Buna-N is suitable for applications where the temperature range is 0-121 degrees C and has good resistance to petroleum-based oils, greases and hydraulic fluids, water and other common automotive chemicals.  Can I use a correctly sized  Buna-N o-ring in this application?


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Rick G

Rick G
admin
admin
The black nitrile O rings will harden over time as you are geting towards the top end of the heat range where the red will remain softer and more pliable.
The nitrile will give probably 3-4 years service there where you can expect 10 from the red ones, they aren't viton but I cant remember what the stuff is called now. It will probably come back to me in the shower and then when I get out of the shower I will think what was that I had to remember.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1999 K1100 LT with a Big Block 1200
    

Agerbundsen

Agerbundsen
Silver member
Silver member
I have only ever seen black Viton , and it is very expensive relative to other elastomers - and not really needed here. Most likely the original red one is a silicone rubber, designed for the high temperature.

    

Rick G

Rick G
admin
admin
I suppose they can make it any colour they wish. Here in Oz the only one I see is a light brown to identify it from nitrile.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1999 K1100 LT with a Big Block 1200
    

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