Can you still get the housings from ford.My mates from work is leaking from around the housing.I coulld be the gasket.

 

Most likely a cracked housing mate,
These crack quite regular

 

I have one Genn. Off the engine in my mk2 escort

 

I heard it was a common thing.Im sure i heard that ford no longer sell them.

 

It my mate needs one i might get it off you for him.

 

It will be the rubber seal on the bung that fits into the bottom of the housing! You can get a new bung and seal from Ford. Very common on the st170.

 

When your under the car it looks like the coolent is coming from inbetween the head and the thermo housing.

 

Well it is very very very common for the plug seals to fail on the st170 so I'd deffo be looking at that first. You can't see it easily as it is underneath the thermostat housing.

 

If the stat housing does turn out to be cracked, don't bother buying a second hand one. The three torx screws that hold the stat cover on normally rot into place and snap when you go to undo...

Learnt from experience lol...