When I fill up the water in my car I fill it up to the max and maybe a day or so it goes down quickly but when I am stationary there is no signs of leaks why is it drinking much coolent wot can I do to find out if I have a leak on my St 170

 

If it was an astra-( coolant smelling of fuel/fumes)it would point to the cylinder head-but st170!-??

 

Thermostate housing leaking, it only does it when the engine is running, hence why you cant see a leak, you should see water staining on the gearbox though as an indicator. The thermostate will either require a new bung with o ring or will be cracked and will require replacment, Looking at around £200 from ford for a new one