I've been having some trouble with the idea of "Oil" leaking from the valve cover and draining down in behind the water outlet housing and damaging the rubber seal, leading to the seal leaking coolant.
What is it about a rubber seal that oil would cause it to swell and break the or crack the housing?
Mines leaking coolant and the valve cover isn't leaking?
I know at lest one other person who has a Focus that has the coolant leak and a dry valve cover?
I can help but to think that the newer coolant chemistry is attacking the crapy rubber seal.
After actually having the new Motorcraft housing and seal in hand, the seal looks more like a flat rubber drive belt out of a tape player, rather than a seal. If I end up keeping the motorcraft housing (If I can't send it back) then I'm thinking about tossing the factory seal in a tub of 50/50 mix of coolant for a month or so and see if it swells up.
I don't like the "Flat" thin "Wall" and extra "Tall" design of the seal. Also its in a rather wide grove, so I can't see it compressing before it flops over? its a crap design for sure
One thing I thought of might be to set the housing up (seal side up) and level. Then fill the seal grove up about half way up with a flow-able sealant like "Goop". let it set for a couple of days, then just put in a regular O-ring seal. Anything would be better than the OEM setup.