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fuel sight gauge

RAC cubs

Registered User
racine,wi
had one leak for the first time, are the top and bottom rubber the same, how tight do you go ,hand tight or wrench ,before glass breaks ,do you use sealent, fuel lube or dry threads.do you replace ball?
 
Rubber is not the right material. Had a customers airplane once with rubber gaskets, auto fuel swelled the hole shut and gauge showed fuel left, tank was empty. Cork is what belongs in there.
 
Use cork. Fuel lube. But not so much ball gets stuck to it. Hand tight

RAC, like Mike said, original gauges use the cork. You don't want to over tighten them because it crushes the cork gasket and they will leak and maybe lose bits of the gasket into the fuel supply. Just tight enough to squish the gasket down, not tight enough to crush it.

Some replacement gauges, like the Dakota Cub high-visibility ones, use a series of o-rings.

--Amy
 
Switching back 'n forth between mogas & 100LL makes the cork expand/contract so will weep a bit. In mine it stays dry if I stick with mogas.
 
I just put a microscopic amount of engine oil on the cork gaskets to make them slippery so that they didn't tear when tightening fittings down. Ball doesn't stick nearly as easy as it does to fuel lube. worked perfectly
 
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