Just redid the heads on my 4.0 2001 S-Type. All new gaskets, car ran great, but has now developed a right side oil leak from the valve cover. Took it apart, examined the gasket and the rubbers under the bolts, everything seems to check out, still small stinky leak. any ideas?

 

I have the 2000 model with 55,200 miles and last year I couldn't stop the leak until I bought a new valve cover for the driver's side. It cost for the whole kit about 234.00 dollars . That includes new bolts and gaskets. And when you put it on only tighten enough to hold it in place. If it leeks you may need to turn the bolts "slightly" more. The valve covers warp over time!

 

Protocol calls for RTV sealant on the front ends of the valve cover, where the timing cover meets the heads. You also can try the RTV sealant on the lower corner of the cover where the gasket meets the head.

As pointed out the cam covers do wear over time, especially when the bolts are over tightened - I had a pesky leak and placed a thin strip of RTV sealant in the lower corner of the valve cover (placed on head and seated the cam cover in place and torqued bolts per JTIS spec) and it did the trick.