help with radiator problem

[EVO-V]

distilled water lang po, walang halong coolant..
every week ako nagrerefill sa reservoir eh.. ok lang ba yun??
kasi kung normal lang maglalagay nako coolant and tubig 50/50

There are very finite causes of leaks unless your radiator itself is damaged.

Check the following:

1. Inlet hose and attachments from the engine to the radiator.
2. Outlet hose and attachments from the radiator to the engine.
3. Radiator cap.
4. Thermocouple O-ring.
5. Overflow pipe.
6. Water pump.

If no leaks are visible, check your radiator for leaks, tanks, headers, core.

If no leaks are found there's a good chance its leaking into your engine. So check your oil.

Once you find and seal the leaks, flush and refill your system with coolant mixture and clean water.