o-ring Q
is nitrile okay?
TIA

I removed the intake manifold and these O-rings are dead and I'm searching a replacement set..
-Beppe-
Of the Many different polymer compounds used to make O-rings, several are compatible with hydrocarbon based fuels (with or without methanol content): Flurocarbons (or FKM, also called Kalrez or Viton), Epichlorohydrin (CO, or ECO), CSM, HNBR. Viton will be the most commonly available.
Many others are NOT compatible - they exhibit excessive swelling or other reactions (swelling by itself, in a static seal/fixed cavity size application, isn't All bad - it'll seal OK, just don't plan to re-use it...): Nitrile (or NBR), Buna or Buna-N, Ethylene Acrylate (AEM), Ethylene Propylene (EPM , EPDM), Butyl, Chloroprene, Any of the various Silicones. Buna-N is what most hardware stores will have on the shelf - best to stay away from them for automotive uses.
It is not usually safe to generalize by color - any of the compounds can be tinted. Most usually are Not, but it depends on the manufacturer... GM used to specify a Brown color for their (Kalrez, I believe) O-rings, that's why you usually see replacements that are brown in color. "Normally" a brown or Rust colored O-ring is a Silicone based product...
Generally, don't plan to reuse a fuel system O-ring - throw it out - Cheap insurance. Any of the auto parts stores carry replacements, usually packaged as a "kit".
Someplace in the toolbox I have a bag with a bunch of spare Kalrez (Black in color..) fuel system O-rings - labelled by the standard industrial sizes. I don't remember off-hand what those sizes Are, but there are two different ones that GM uses about everywhere. I Want to say that they are a 2-008 and a 2-011, but don't quote me...
Look on the bright side - Brake fluid compatibility, complicated by the different base material brake fluids, is Much tougher! About the only commonly available materials that are compatible (usually, depending on the brake fluid in use) are Buna-S (SBR) and the Silicones. Note that most brake fluid applications are NOT static assemblies, but situations where the o-ring is a moving seal (dynamic) - much tougher in terms of material wear and etc..
Finally - for ANY O-ring question, the "Bible" is the Parker Hannifin O-ring Handbook. It Might be found someplace online, I'm not sure..
Of the Many different polymer compounds used to make O-rings, several are compatible with hydrocarbon based fuels (with or without methanol content): Flurocarbons (or FKM, also called Kalrez or Viton), Epichlorohydrin (CO, or ECO), CSM, HNBR. Viton will be the most commonly available.
Many others are NOT compatible - they exhibit excessive swelling or other reactions (swelling by itself, in a static seal/fixed cavity size application, isn't All bad - it'll seal OK, just don't plan to re-use it...): Nitrile (or NBR), Buna or Buna-N, Ethylene Acrylate (AEM), Ethylene Propylene (EPM , EPDM), Butyl, Chloroprene, Any of the various Silicones. Buna-N is what most hardware stores will have on the shelf - best to stay away from them for automotive uses.
It is not usually safe to generalize by color - any of the compounds can be tinted. Most usually are Not, but it depends on the manufacturer... GM used to specify a Brown color for their (Kalrez, I believe) O-rings, that's why you usually see replacements that are brown in color. "Normally" a brown or Rust colored O-ring is a Silicone based product...
Generally, don't plan to reuse a fuel system O-ring - throw it out - Cheap insurance. Any of the auto parts stores carry replacements, usually packaged as a "kit".
Someplace in the toolbox I have a bag with a bunch of spare Kalrez (Black in color..) fuel system O-rings - labelled by the standard industrial sizes. I don't remember off-hand what those sizes Are, but there are two different ones that GM uses about everywhere. I Want to say that they are a 2-008 and a 2-011, but don't quote me...
Look on the bright side - Brake fluid compatibility, complicated by the different base material brake fluids, is Much tougher! About the only commonly available materials that are compatible (usually, depending on the brake fluid in use) are Buna-S (SBR) and the Silicones. Note that most brake fluid applications are NOT static assemblies, but situations where the o-ring is a moving seal (dynamic) - much tougher in terms of material wear and etc..
Finally - for ANY O-ring question, the "Bible" is the Parker Hannifin O-ring Handbook. It Might be found someplace online, I'm not sure..
Wow! Great info. Thanks!


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so the charts in the book show that nitrile is satisfactory but would it still be safer to run to the stealership rather than just grab a couple nitrile ones from work?

Anyhow, viton is only used by GM on the fuel rail hookups to the hard fuel lines, nowhere else, in 85. Interesting though, is those are the only ones that I end up having to replace everytime I mess with them, because they get smashed to hell.
Anyhow you might find this useful...
http://webpages.charter.net/khasting...uelsystem.html
Thanks for the links, very good info there!
Anyhow, viton is only used by GM on the fuel rail hookups to the hard fuel lines, nowhere else, in 85. Interesting though, is those are the only ones that I end up having to replace everytime I mess with them, because they get smashed to hell.
Anyhow you might find this useful...
http://webpages.charter.net/khasting...uelsystem.html
in the link posted (thanks) it seems that these two o-rings are different sizes. Looking in my metal line it seems that these two orings are of the SAME size...
I found 2 black rubber o-rings. Is it safe if i use the car for some weeks until i can reach the correct replacement?
-Thanks
-Beppe-









