Oil pouring from valve cover gasket

I had leaky rocker cover gasket problems on a Peugeot Diesel caused by overtightening the rocker cover. The seal was rubber and didn't work properly if it was oversquashed.

Check that the oil breather pipe is not blocked, I had a similar problem with a 2lt Audi engine and I eventually found that the pipe was blocked with crap and the engine could not release the excess pressure in the crank case and so forced oil out every where it could. I know I have not used the correct technical terms to explain this, but if you can follow what I am trying to say then look at it. Some of the other posters will be able to explain this better.

Take a look at this: under Car-Care Videos, the last but two, "Repairing an Upper Engine Oil Leak".

Having redone everything, it seems I've been sold the wrong rocker cover gasket. The cylinder head bolts have a raised round base which the rubber gasket doesn't seem to accommodate.