Does anyone make a gas cap gasket that holds up to ethanol fuel?

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Auto Shop teacher
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Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by Auto Shop teacher » Sun Dec 22, 2019 9:17 am

My railroad museum mule has a non stock gas cap and I started smelling gas. When I noticed the filler neck wet, I took of the cap and discovered that the rubber seal was cracked and split. Considering that it is only about 3 years old I suspect that the alcohol additive in the gas we have to buy is to blame for its early demise. Does anyone sell new gaskets or gasket material that will work, and is there a stock automotive gas cap with ears on it that I can buy that works.

This is a working mule I use at our RR museum and is not a parade mule so a regular gas cap will be fine if someone has a part number to order one. Thanks in advance.

markrdje
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Re: Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by markrdje » Sun Dec 22, 2019 11:34 am

I am sure an auto parts store would have it
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eclipse
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Re: Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by eclipse » Wed Dec 25, 2019 12:22 pm

Make a cork gasket.
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muleman7
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Re: Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by muleman7 » Wed Dec 25, 2019 7:46 pm

John Emery has the Viton Gaskets that are replacements for your hard and cracked ones. The viton will withstand ethanol.

The Fuel pump kits I sell for the AC flat top 2cyl engines use a Buna-N diaphragm and Viton for the check valves.

The instillation I found that works for me is to grease the gasket and the fuel cap where the gasket slides over and into place. I hold the cap tangs on the cap in a vise to allow two hands for instillation. I use an 1/8" long pin punch to help slide the gasket into place. Be very careful as the gasket can split. Work the gasket over the locking tang opposite the vent lever area and into position then the remainder will slip into place.

See the below PDF link.

http://iqlearningsystems.com/ethanol/do ... bility.pdf
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Re: Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by Auto Shop teacher » Mon Jan 13, 2020 8:17 pm

Thanks Charles, I talked to John Emery and he said his gaskets were made for the 4 cyl early mules and he isn’t sure it will work on the later models. Do you know how thick the gasket material for the gas cap is?

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Re: Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by muleman7 » Mon Jan 13, 2020 8:30 pm

I will check an original new A2 or A5 gas cap and post.
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Re: Does anyone make a gas cap gasket that holds up to ethanol fuel?

Post by muleman7 » Wed Jan 15, 2020 3:32 pm

I checked a NOS M274 and NOS A2 or A5 Fuel Gauge Rubber Gasket thickness. Using both Mic and Digital Caliper: They were measured while installed on the cap and did not allow much surface to gauge when pried up.

The M274 gasket measured 0.0915

The A2 or A5 gasket measured 0.087

John's gasket measured 0.086

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