I have an o4 F150 5.4 3 valve that developed massive oil leak. long story short there is a rectangle hole with long crack about 1/3 way up top lip on passengers side of the alum cover. what could cause this. I know cover is in order what else could be wrong?

 

That's usually caused by a disintegrating timing chain or tensioner guide. Pull the cover and take a look, you may have to pull the front cover and drop the oil pan to get all the pieces out.

 

after looking at pics whole timing kit will be needed hope no more damage. now to find cover.