O-rings for E10 fuel?

[SLR No.77]

Can anyone knowledgeable help with which material would be best for replacement O-rings to enable compatibility with E10 fuel?

Theres a myriad of choices …

- Nitrile
- Viton
- EDPM
- PTFE
- Polyurethane
- Hydrogenated Nitrile
- Silicon

Stu.

[7 wonders of the world]

I would say Viton, ISTR there are brown and green, cant remeber if theres a different in material compatibility though, or maybe temperature range

[SLR No.77]

I think the generally available green o-rings are the Hydrogenated Nitrile versions which are used in air con pipework … obviously not relevant in a 7!

[TomB]

Are you thinking for injectors and fuel rail? I changed all my fuel rubber pipe to R12 (I think) when I rebuilt the car, but admit I didn’t think about the O rings. 

[SLR No.77]

I’m doing the complete fuel systems on both the Caterham and the Mini. I’ve started with Gates Barricade R14 hose but won’t be satisfied if there’s still potential for ethanol induced leaks at other points. On the Caterham it’s the six o-rings on the fuel rail, connectors and injectors, so far on the Mini it’s the connections to the fuel filter. I’m sure I’ll find more though.

[ECR]

Viton 👍

[paul richards]

Stu. Interested to see how you get on with this exercise. I think your car is similar vintage to mine and I thought about changing the rubbers but decided against. Changing O rings and hoses seemed OK but it was gaskets around the fuel pump and gauge sender that put me off as they can be a pig to seal. You’ll probably tell me they don’t need changing as they are cork but I wasn’t sure. For the relatively small amount of fuel used I’ve decided to use the more expensive E5 super fuels or when not available use THIS. 

[SLR No.77]

I’m currently using E5 but the situation is likely to get worse not better, plus European touring might become an unknown. The fuel pump gasket is a moulded rubber item and one I’m going to investigate further. It’s a very similar moulded gasket on the Mini which is a similar age to our 7s and might even be the same item … it certainly looks familiar!

 

[TomB]

7 hours ago, SLR No.77 said:

I’m doing the complete fuel systems on both the Caterham and the Mini. I’ve started with Gates Barricade R14 hose but won’t be satisfied if there’s still potential for ethanol induced leaks at other points. On the Caterham it’s the six o-rings on the fuel rail, connectors and injectors, so far on the Mini it’s the connections to the fuel filter. I’m sure I’ll find more though.

Are there O rings on the pump & fuel filter connections? If you do an order for the others let me know please 👍

[Gridgway]

Just a silly off the wall question, but are we sure that it's ethanol that is the problem?  My BDR resto project had fuel in that was pre-ethanol (yes, that old) and the fuel pipes were completely shot.  I think it's a very difficult problem of very poor quality rubber that just hardens and breaks with exposure to petrol.  Nothing to do with ethanol.

But that's just a theory.

[SLR No.77]

That might be the case for an older car and I’ve certainly had fuel pipes perish and leak in the past, but it took many years for the problem to appear. My understanding with ethanol is that unless the correct ethanol resistant material is used, or an inhibitor is added to the fuel, the pipes will become damaged in a much shorter time.

My last fuel pipe failure was the pump to filter pipe under the rear wheel arch which perished and leaked at around 10 years old. I’d disturbed it doing another job which had caused the cracks to open slightly, thankfully in my garage I could smell fuel so knew there was something wrong. I certainly concur with the thought that components will become hard and fail, and I do believe ethanol is now an added concern.

[TomB]

I think you'd have to do a full strip down of the fuel system to find each O ring.  Anything in the in tank pump apart from the gasket?    

[Jonathan Kay]

11 hours ago, Gridgway said:

Just a silly off the wall question, but are we sure that it's ethanol that is the problem?  My BDR resto project had fuel in that was pre-ethanol (yes, that old) and the fuel pipes were completely shot.  I think it's a very difficult problem of very poor quality rubber that just hardens and breaks with exposure to petrol.  Nothing to do with ethanol.

But that's just a theory.

I hold to my previous conclusions:

1. It's very important to look for appropriate automotive standards on new materials as well as at the type of material. For several decades those standards have included resistance to fuel containing 10% ethanol.
2. Sevens are likely to use unusual and DIY parts. Inappropriate materials and products used in this way may account for some of the problems in the past.
3. Sevens last a long time, and components of the fuel system should be thought of as consumables on a scale of decades. That includes checking. 

Jonathan

[Jonathan Kay]

I've looked at the claims and composition of  "STA-BIL 360° Protection Ethanol Fuel Treatment & Stabilizer".

Is there any evidence that this provides any long-term protection to fuel system components?

Thanks

Jonathan

Edited December 11, 2023 by Jonathan Kay

[Gridgway]

1 hour ago, Jonathan Kay said:

I hold to my previous conclusions:

1. It's very important to look for appropriate automotive standards on new materials as well as at the type of material. For several decades those standards have included resistance to fuel containing 10% ethanol.
2. Sevens are likely to use unusual and DIY parts. Inappropriate materials and products used in this way may account for some of the problems in the past.
3. Sevens last a long time, and components of the fuel system should be thought of as consumables on a scale of decades. That includes checking. 

Jonathan

Yes indeed Jonathan.  Just my thoughts

1 I assert that even those standards which claim ethanol proof don't seem to produce hoses that have longevity

2 Good point, but it's not hard to find fuel hose that is proof against ethanol and no sensible Caterham DIYer will be fitting cheap tat I suspect!

3 Many (petrol) cars last a long time (measured in decades).  The Fabia on the drive is 17 years old with 130k miles.  It doesn't seem to need new fuel hoses

Something doesn't stack up.