Raidator water level very low and overflow reservoir full

[akashkhan2008]

Hey Guys!!
I have recently observed that at the end of every work day my car’s(indus corolla 1.6gli 4a engine) radiator drops water level about 250ml while the overflow bottle gets filled up to the brink which was half filled in the morning. Water is coming out of the bottle into the rad after cool down. What could probably cause that?
Thanks in advance for the suggestions

[mshoaib432722]

Change radiator cap with a brand new one. And then tell if this thing happens again.

[akashkhan2008]

Will do Insha Allah

[humayun.chughtai.7]

Replace radiator cap at first priority.
Look for any leaks, seems like air is entering the cooling system from somewhere.
What is the condition of radiator ? Is it rusty inside ? Is the thermostat valve at its place ? Fan auto or direct ?

[akashkhan2008]

Well on inspection of the cap I found two cracks in a seal maybe thats the trouble. The rad hasbeen washed but not that thoroughly as I took it to a roadside mech for cleaning. Might still have some rust inside. Couldn’t get the thermostat checked so can’t say and I put the fan to direct as a precaution.

[humayun.chughtai.7]

If the temperature needle stays at HALF mark even with direct radiator fan, then for sure T-stat valve is there.
And if the needle remains below half near the COLD mark, then you have no T-stat valve.

[humayun.chughtai.7]

Keeping the radiator fan direct is a bad thing for your engine as well as the fuel average.
I will recommend you to get it back to default settings.
And in these engines, the temperature sensor works on fail-save mechanism i.e. if the sensor got bad, it will make the radiator fan to run all the time i.e. direct !

[akashkhan2008]

True!!