What is the difference in the O ring colors as they come from Mercedes? For my recent delivery valve/fuel line O ring replacement job, I received mostly black O rings from MBUSA. I understand them to be the nitrile/buna rubber composition. However, there were a couple of O rings that were green in color. Two were for the fuel pump and the other was for the banjo bolt on the fuel line that bolts into the back of the injection pump using the two copper washers. The size isn't the difference because they were the same size as some of the black ones. I did replace all of the Mercedes supplied black O rings with viton though.

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Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

What color are your Viton O-rings? Most of them are brown but that is not true 100% of the time. They could also be black, or other color according to a Hydraulic shop near me. I am not sure if there is a good way to tell visually tell what material an o-ring is made from. How about heating it up if you don't mind a destructive test? Viton is good up to 400F from memory. Or is that 500F?
NBR is much lower. I am guessing somewhere around 300F.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

All the viton O rings were black.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

Color is not a good indicator of material.

There is a tool available that "bounce checks" the material. The tool I have requires that the o-rings be new, no smaller than a series 100, no larger than a series 400, and be 70 durometer. If they meet that you can bounce check them. It looks like a pen with a slide inside of it. You raise the weight to the start point and then drop it. The height that the weight bounces to determines the material. Viton gives less of a bounce than buna.

That is the only way I have to check it, other than to buy from a reputable dealer and don't get your o-rings mixed up!

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

Jim - thanks for the reply. On another note, I mentioned to you in another post that the O ring package you sent me was fine and that it looked like there was one extra 2.5 x 8 mm O ring. Well the extra O ring belongs on the banjo bolt that fastens one of the fuel lines to the back of the injection pump. I had forgotten about that O ring and as it turns out, that was the one that was leaking on mine.

So your kit was perfect.

Thanks again.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

Sweet!

__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.