Fuel Filler Leakage

FYI: While taking a short trip a few days ago I smelled gasoline odors. The driver of the car following said it was more like a stong smell. Turns out the "safety" screw-on cap under the standard fast fill-cap was leaking. I'm sure the leakage was aggravated by full fuel tanks and hard cornering. Although the flip-up cap contained the gasoline, the lost fuel drained out the overflow and under the car and behind the left front wheel . . . the right tank sealed okay. Seems as though a slight twist of the cap corrected the leakage problem.

Although mine is an ERA, I talked with Dennis Olthoff (Superformance) about the problem. While we were on the subject, he said all Superformance car with fast-fill caps are fitted with screw-on caps for safety reasons. Also, it turns out that GT40s leaked a little from the caps due to the low pressure developed above the caps at speed. This caused fuel to siphon, albeit slightly, from the tanks. This leakage and safety concerns, especially accidental opening during an unfortunate upside down situation--have made the backup screw-on caps a good idea.

At Le Mans in 1967, Mike Salmon was driving P/1026. Fuel leaking from the filler caps was carried by airflow over the back of the bodywork where it was ignited by the exhaust. The whole car went up in flames and was totally destroyed; he was lucky to get out alive.

(Incidentally the car was salvaged and a ten-year restoration finally had it back on the road).

Point being, a belt-and-suspenders approach to the fuel fillers is definitely a good idea; the flip-caps should be considered a backup to the primary means of securing them, that being proper screw-on caps underneath.