hi all,
my car is iswara AB 2003.
last week got overheat issue (water pump leak) luckily i already reach home and the engine still running. reserve tank already dry and vapour came out....

next day, after topup the water fully, drive about 5km to workshop and change the waterpump. then go to service the radiator at radiator workshop. change the cap also.

now the problem is, the water in reserve tank always decrease. let say i topup full this morning, then drive around 100km, when check back, sure already decrease about 30~50%. so worry because already check not found any leaking at hose, waterpump etc...

just now my kolik see the engine and say that maybe the valve/choke (???) at the carburator already leaking and need to change the whole carburator. he show me the part and i do see a green color similar to my previous coolant at that part at also that part look rusty.

anyone have any advise?

think that i may think the issue :
- engine gasket already burn. but check using engine oil dip not found any traceable of water.
- thermoswitch below radiator already defect. this will cause radiator fan not blow accurately/long time to response.
- choke/valve as per my kolik say (still not sure bout this as i tot carburator only deal with fuel and air only)...

blown head gasket?

this one if change how much? u know a? anyway, as per my post, there's no evidence that oil already mix with the water as i check in radiator, reserve tank and check engine oil dip.

but will noted your suggestion...
thank you,

some decrease in the reserve tank is normal...

however if you can visually see coolant traces/leak then definitely need to get it fixed, doesn't matter where it is.

The car cooling system is suppose to be a closed loop. Small leaks can lead to major failure in future.

Most of the time small leaks will quickly evaporate due to the hot engine... so that make it difficult to spot. But coolant traces is a tell tale sign something is wrong

1 thing you need to notice.

The radiator top fibre cover failing is 1 of the cause of water leaking from the closed loop. Check that one too. Not very expensive to replace.

there must be leaking somewhere..very the small one..it will not notice because it will dry out..setitik setitik lama lama jadi tasik

Do a pressure check, if there is small leak, will be found. If above fail, maybe the radiator cap you replace is not the right one, change another one and see if it work. If that also didn't work, look into the fan and relay. Above is assuming no leak into you engine.

I had same problem last few months. Every week need to top up water. Checked the radiator was rusty so I decided to change the whole radiator & water pump. So far everything is ok, no need to topup almost every week like I used to

I had same problem few days. Every morning when open bonet need to add alsot 300ml water. I did saw some leaking in the afternoon one time. but cannot see sometime. Why?

it's better to use UV color coolant like UV green or just normal red color coolant.

so when you park at clean floor like shopping mall parking.

if any leak you can notice.

i kena before, park my car at pavillion, come back the whole engine bay floor area full of "RED" water.

so i know it's water coolant water leak liao.

in my case is bottom radiator hose crack, cause the leak.

you might want to look into top and bottom hose.

check also your radiator top cover see if any crack ( not radiator cap )

other than that look at your water pump area ( near timing belt and pully area ) to see any noticeable water mark stain like UV green stain or red color stain.