[T3] Valve. Covers..

[ftalker at gmail.com]

Hi there
While there may be many reasons for covers to leak, particularly after their recent removal, my experience tells 
me that a likely culprit is a gasket which slides out of position, (mostly, but not always on the bottom), creating the leak.
One thing I did on all of my VW covers, (I keep a set ready to install), is to braze a two inch tab parallel with the sloped, more or less horizontal interior bottom-side, extending outward toward the "head" and no farther than the cover's outside edge dimension.  This prevents the aforementioned slippage of the gasket, (particularly on oiled or greased gaskets), off of its intended ledge and into the cover's interior...not good.
  With a smooth slather of RTV red silicone on the cover side, the gasket goes in place for many leak-free motoring miles.
While I cannot post a picture here, I would be willing to do so for those who email me directly. 
Hope this helps.
Best regards,
FE Meek

Sent from my iPhone