Fuel Gas Petrol Filler Cap Gaskets (dhc later fhc)

[FI Spyder]

I made my own seal from a spare sheet of neoprene (but nitrile would be better but it's not sitting in gasoline so will be fine). Cut it out with scissors and the screw holes with hole punch. The foam part that goes hard can be made with a sheet of foam (closed cell so it doesn't absorb water is preferable). Gas caps can easily taken apart and the old parts can be used as a pattern.

[John_C]

Did you replace the rubber seal that locks the fuel in the tank and stops water running in from the top? The seal is the most important part as I can testify having suffered water getting into the tank in heavy rain.

[FI Spyder]

Yes, that's the one I cut from a sheet of neoprene as the old one was rust embedded and compressed. Also while you're at it make sure the spacing that allows water to escape isn't blocked by crude. While the plastic inset was out I replaced the mauled screws holding it in with stainless steel allen head ones.