If it's a 2.4 then you may have to fit just a new pump. Just changed the gasket on mine and tried sealing it 3 times. Still leaked. The problem turned out to be the seal on the bearing leaking behind the pulley.
The only way to tell is to take the pump off and really clean the area at the back of the pulley, then refit and roadtest. If the leak is still there then carefully take the pump off but keep it upright, then look behind the pulley for oil. If it's wet, you need a new pump. (Ebay 50 quid or so. Ford a lot more.
By the way. I got a new thin gasket and the dearest 'o' ring in the world. The original was a thick plate. I used the thick one with some BLUE HYLOMAR sealant on both sides,but don't get it too close to the oil holes.
No leaks or patches of oil everywhere yet after 2 weeks.Even had oil spots sprayed up the back doors,what a mess.
Good luck.
Tbird, October 2007
