Fuel cap issues.

[Bombay Mix Pilot]

Hi All, Just a quick question, Anyone had issues with fuel tank cap seals reacting with current petrol ? I stopped for fuel on Friday, when I removed the tank cap the seal had expanded ( diameter ) so much that I was unable to refit the cap so had to discard the seal and clean up the mess when I got home. The cap was a brand new one from Scooter restorations. Maybe another item that needs making in Viton.

Andy

[storkfoot]

They all seem to do this. Stick it in boiling water for a minute or so, take it out and dry it, and it should have shrunk enough to get it back in. Last time I did this, I glued it back in and it's been fine since.

[Bombay Mix Pilot]

Cheers Storkfoot, the stainless Scoot RS one on my other scooter aint done it though, seems to be a more plastic type seal but has worked really well.

Andy

[GP Kevo]

Yes, it's the ethanol in the fuel reacting with it. Mine did that, too, on a new cap. Could be a cheaper rubber used nowadays. Time for Viton fuel cap seals. Or better, a proper fuel.

[CutdownSpence]

Happened to me also so I cut my own out of 4mm rubber sheet seals better too.

[victor]

Yes, it's the ethanol in the fuel reacting with it. Mine did that, too, on a new cap. Could be a cheaper rubber used nowadays. Time for Viton fuel cap seals. Or better, a proper fuel.

It's not the ethanol, this is a modern myth as ethanol is less reactive with any plastic and rubber than is petroleum based products (which is why you don't have any problems with the plastic in your cars windscreen fluid (ethanol) washer container and system).

It's most likely the additives (chemicals to clean carbon, increase friction etc) that the fuel producers add to the petrol nowadays that's to blame - have a look at the following for example:

http://www.maidata.com/Img/petro/Suppor ... 587007.pdf

The last one (rubber) I got from SIP is still holding up well after nearly a month.

[GP Kevo]

Ethanol is highly corrosive to brass, many plastics and rubber and especially fiberglass. Glycol should be used in car windshield cleaners, it's what they use in the USA. Most new cars come with a different plastic tank and hoses nowadays that are more resistant to ethanol. Check the reports from the USA, where they have been using E10 fuels and soon will use E15. Marine dealers and small engine shops have reported lots of problems from the ethanol in the fuel.

[GP Kevo]

"We have recently seen several issues of concern that appear to be related to gasoline containing Ethanol (Gasohol).

Blends above 10% are likely to cause problems in vehicles not designed for alcohol. These problems include delamination (chemical breakdown) of rubber, plastic, and synthetic components such as; rubber, plastic, and synthetic hoses, fuel lines, plastic fuel pumps, plastic fuel tanks, fiberglass fuel tanks, fuel tanks that are epoxy coated, or with rubberized, or plasticized liners, and aluminum, copper, brass, or bronze fuel system and injection system components.

Vehicles stored with gasoline containing Ethanol in the fuel tank are more likely to have problems with the alcohol causing component corrosion, deterioration, and breakdown.

Special plastics, corrosion resistant stainless steel and other more expensive components must be used in any component that touches fuel containing alcohol.

Ethanol is much more hygroscopic than regular gasoline. This holding of dissolved or suspended water can lead to more component corrosion; and gum, varnish, and carbon deposit formation problems.

Ethanol is not as volatile as gasoline, therefore as the percentage of alcohol increases; the engine becomes progressively more difficult to start in cold weather conditions.

Ethanol is a strong solvent and has been used by industry for hundreds of years to clean various types of contaminants and to dissolve and suspend solids.

Gasoline with dissolved solids (plastics, styrene?s, rubber materials, etc.) that will tend to reform as the fuel evaporates. The reforming of the dissolved material shows up as deposits in the fuel system and engine. This material has shown up as deposits on the throttle plate, injector?s piston crowns, and exhaust valves. It is also a problem with PCV?s systems and turbochargers."

In some cases, particularly in the marine markets, gasoline containing Ethanol has been found to saturate and partially dissolve fiberglass fuel tanks. This has been found to cause severe engine problems and very serious safety concerns from leakage.

There is also a problem where Gasoline, MTBE, Ethanol, and Water come together. This combination can cause formations of a thick, gooey, black material that wreaks havoc on fuel systems.

http://www.enertechlabs.com/ethanol_in_gasoline.htm

[victor]

The last one (rubber) I got from SIP is still holding up well after nearly a month.

EDIT - The SIP rubber packing has now swelled as well so NOT holding right quality!!!

[victor]

Believing myths is easy but the facts are out there - go checkout a chemical resistance table for various plastics on the net and 9 out of 10 plastics and rubbers will show up as more resistant against alcohol than petrol.

It is indeed hygroscopic but for someone who actually drives their vehicle frequently (and not only vans it around the country to the occasional ride out or rally) this will not be an issue. Just as it isn't an issue for cars which are much more sensible with their modern injectors.

We are running stone age technology and a few percent of alcohol will not be noticeable and have any effect on your plastics - it's the unknown chemicals that are added that potentially could do that (although myself and most people I know who are somewhat technically knowledgeable and use their scooters for what they are made of have no problems what so ever, and drive daily throughout the year and refuel where ever is the closest).