salam.bhai mery pass 1.5 years sy mitsubishi I 660 cc car hy. poora 1 year mujhy os k radiator main pani nahi dalna para. but 2 month pehly mujhy os k ring replace krwana paray . ab os main roz pani kam ho jata hy. roz half liter pani dalta hoon radiator main. iss ka engine peechay hy and radiator front py hy.sari pipe line check ki hy. koi leakage nai hy. mechanic kehta hy k gas kit theek hy. phir paani kiun roz kam ho jata hy.
your car would have bleeding ports to remove air, and dont use plain water in it it will completely destroy the pipes that are under the car. Test first with a pressure tester and then find your leak.
have you checked the engine oil is it milky? maybe thats where the water is disappearing, also check if there is any water underneath passenger carpet or trp replacing radiator cap or check if any where press is being lost in reservoir
flush engine & use coolant - read this
it has the subaru domingo/toyota MR2 fill procedure and problems too - and volume.. - MR2 and domingo take 12 to 14 litres coolant mix
660CC takes that amount of coolant? sigh^ Our Land Cruiser 1HD-FTE also took 13-14L coolant but it is 4.2L l6
Is the fan auto n thermostat installed?did u get it checked from a different mechanic as well? The one who built the engine wld never admit anything
Maybe ring gap issue?
Bhai aap radiator bottle ka cap Chek. Karo us main ek O ring hoti hay make sure O ring ho cap. Main warna pani reserve pipe ya over flow pipe say bahir ajey ga on accelerations on high rpm