Do a search on Evil-Bay for "valve cover spreader bars". There are dozens of them listed and they prevent the sheet metal distortion and oil leakage that's common on stovebolts. Could there be a seep leak at the water pump that's getting blown back onto the valve cover by the fan? Long term inactivity isn't good for water pump mechanical seals.
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!