I am certainly very happy with my Jaguar since I bought it in 2008. However, I have spent a few thousands in several repairs like replacing the the valve cover gaskets and the cam chain tensioners failed and we had to replace all, and also the oil seal.

But since we changed the cam chain, every time we park the car after driving it smokes all over the engine through the hood; and it has also an oil leak.

Any ideas of what this can be or does anyone have experienced this?
Thanks!

 

Welcome - it sounds like the very common problem of cam cover seals leaking onto the exhaust manifolds. You can check this by running some paper towels between the cover and manifold, if there's signs of oil, you've found the smoke source.

Over tightening the cam covers can lead to cracks around the bolt holes - check these, and any loose bolts along the covers. If these are OK, it might be time to buy new seals.