Losing coolant on a s type v6 sports 2.5ltr
bit of a weird one my s type has a low coolant warning come up but the coolant reservoir is full then I drive it a few miles and the reservoir is half full?
I undo the reservoir cap and it sounds like air hissing
theres no water in the oil and the car doesn’t overheat at all, the heater works ok although the air con needs a re-gas. Car drives lovely very confused so is my mechanic.
Just 275 miles and have not lost any coolant did another 22 miles town trip and its half full having to put 1 litre in at a time.

 

Have you, or your mechanic, pressure tested the cooling system? It may well be that a leak opens up as the car cools and expanded surfaces begin to shrink...

 

+1 on cooling system pressure test.

Allow the system to cold soak, preferably overnight, then pressurise the system to 1 bar. If the pressure begins to drop on the gauge, inspect the system connections and hoses for leaks.

 

thank you