pop-up gas caps

Does anyone know if these are any good? I've heard they seal well and water can get in. Is that what happened to that black S-10 that started on fire because he was trying to drain water that got in? i'd like to put one on, but not if they don't seal well.

i have one on my astro van, it just all depends on the quality of the cap and where you put it i think...

Cheap ones don't seal that well. The ones that are over $100 and all metal seal pretty well, and not much water will get past them. The mounting angle also has to do with it. If water will sit above it for extended periods of time any cap will leak.

i had mine in my bed rail and never had problem til it got cold and rained and froze then i learned to just leave it popped up when it was pose to freeze