Protecting your cork float

November 1, 2009 | By Richard Prince


I want to protect the fuel gauge cork float in my Packard’s gas tank. What is a safe coating to put on the cork to protect it from the corn alcohol now used in gasoline?

Or is coating my 1937 Packard cork float not necessary?

Also, will this new gas affect the latest types of fuel pump diaphragms?


Most older cork sending unit floats will absorb some fuel and get too heavy to work properly if they are not coated with something that’s impervious to the fuel.

A chemical “paint” designed to seal fuel tanks will protect your cork float from the corrosive effects of alcohol-containing gasoline. One example of a coating designed to resist today’s fuel is POR-15 fuel tank sealer.

Another option is to substitute a brass float for the original cork unit. NAPA stores and other well-stocked parts stores normally sell a variety of different brass floats. Vintage car enthusiasts often use a

Ford float (part number COAZ-9202-B) to restore their sending unit to good working order.

Older fuel pump diaphragms and gaskets may be harmed by modern, ethanol-containing gasoline but the latest diaphragms and seals are designed to stand up to today’s fuel.