Where to get quality high-temp O-Rings?

Last time I bought o-rings from the local AutoZone, they didn't have some sizes I needed. Also, the one(s) I got from the hardware store seem to have suffered some damage, prolly due to high engine temps.

So, as I look into purchasing replacement o-rings for my oil-filler cap and my cam-chain tensioner cover, I wonder:

Where do you guys get good high-temp o-rings? Is there a brand or online store I can get them?

Thanks...

Edit: I should mention that I live kinda far away from auto-parts stores (other than AutoZone), so an online resource makes sense for me...

Post edited by: biquetoast, at: 2006/02/19 15:22

No NAPA store near you? That's probably the best source for quality parts, I seldomly if ever hear complaints about NAPA parts.
They are online also.

www.mcmaster.com/ is there and they have just about anything you might want...steve

Most o-rings are Buna-n, if you want high temp o-rings, look at Viton.
Do a google search for viton o-rings and several sources will come up.
One of them has this: www.marcorubber.com/failures.htm
description of common failures of o-rings.
Good luck

Thanks, gang, for all the advice. I like that marcorubber site.

I happened to be out this morning, and went to:

-AutoZone (no longer sell individual o-rings)
-PartsPlus (sold their o-ring kit and don't plan on replacing it)
-Napa (only had a few o-rings, not the sizes I needed)
-the local hardware store (they had a new section of o-rings, so I bought them and will try them).

...I still prefer the website idea... once I figure out Marco's website - or more importantly what exact sizes I need - I'll be better prepared to oder that way...

Biquetoast, Buna-N is good to about 220F. That said it does start to degrade at above 160F. Viton is OK but be aware that Duponts Viton (Flourocarbon)has an uncontrolable shrink rate when molded. That means the same size o-ring in Viton won't have the same diameter or cross-section as Buna. They typically try to mold them on the large side but I have seen them be tight on the ID but not fill the gap due to this.

If you try to use a larger cross-section o-ring in place of the standard one to get a better seal it won't work if it is over 5% bigger. O-rings are only to be compressed by 20% of their cross-section. Any more and your crushing it resulting in a probable leak, any less and it leaks or weeps.

If you have the original get the cross-section and OD of the ring and send me those dims. I might be able to get you a teflon based o-ring. If not I can give you the mil-spec number for it to get an exact high quality from any local industrial seal house. They usually will give you a sample one if you tell them it's for a side job, just go to the will-call counter, those guys are usually OK to deal with.

if you have a hydraulic repair shop in your area stop in and check them out!:whistle: goodluck,happy wrenching!

Best O-Rings for high temp are silicone. They are red or red-orange in color. Good to about 450°F.

ltdrider is right but you have to be careful. There are two types of silicone o-rings out there at least and they are vastly different.

Try to get one that is a fluorosilicone based molding. It keeps most of the temperature benefits but is fuel and oil resistant unlike standard silicone. Even so silicone is pretty bad at handling anything petroleum based (gas, oil, etc.)It tears easy and wears faster than Buna or Viton. It tends to be more prone to be undersized molding issues than Viton. Viton has a green dot on it but a lot of the time it is hard to find the dot on any of these o-rings.

This gets to be like rocket science if you let it when you get into the spec's of materials. Good luck!