Unless there's a counterbore for the O ring to fit into, it will do nothing in the way of sealing. Does the standpipe or the cover have a groove for the O ring to fit into?
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!