68 XKE. I've replaced cam cover gaskets twice with paper gaskets making sure all surfaces were clean. First time I used blue Hylomar which is a silicon based sealer & the second time I used Indian Head Permatex. I still have leaks. I don't see any cracks as well. No leaks around acorn nuts. I see a brand called Cometic gaskets for sale that are pricey and are of a nitrite synthetic rubber that is bonded to an aluminum core and requires no sealer. Has anyone tried these? I did not check the covers when they were off for flatness. Is there a chance my cam covers could be slightly warped and needs skimming similar with what they do to an aluminum cylinder head? Thanks in advance for everyone's comments.

 

People have been trying to keep the cam covers oil-tight since 1948 ! The originals didn't have any hold-down studs at the front where the cam chains are, but this was quickly corrected. I doubt your covers are distorted, but it maybe worth an examination. What is probably better is to clean off both mating surfaces and look for possible paths for a leak. Other thing is to use those supplied by reputable Jaguar suppliers. I never had any problems with the gaskets, only weeping from the hold-down studs. I used to diligently anneal the copper washer every time I had the cover off, but never totally bottomed the problem. It could be that checking the engine breather isn't blocked or partially blocked alleviates the problem or even cures it.

 

Just an update. I spent the $63 and bought the cometic gaskets and no leaks! Well worth the money. The material is thicker than the paper ones. I did not use any sealant.

 

Great news. I will add to my to do list. :-)
It would be great if you could update us on how they hold up after a driving season.
thank you