Mechanics

COOLING SYSTEM LOSING WATER

2010 Hyundai i30 • 34,000 miles

Leaking water. No visible leakage. I can fill up the car to the "F" mark and drive to my destination(e.G. 40km), and check immediately after arriving, then the water-level is still the same. However around 2-3hours later when the car has cooled down, then the water level will drop. On average the water level will drop with around 6-7cm per day, but the last 2 cases the whole bottle became empty.

Hyundai checked the tubes and did 2 pressure tests, nothing is wrong. Replaced the radiator cap. Still do not know what is wrong.

The temperature meter has spiked once up to almost in the red, but not again. It's just below the half mark on average.

I do not use the aircon often(Perhaps 10min at a time, 3times a week). I do use the heater quite often, average temperature setting of 24-28degrees.
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Koala123
February 3, 2012.




You have a loss somewhere and unless it is the cap itself causing it, it will show up on a pressure test. It can be leaking internally into the combustion chamber and be burned out the exhaust via a blown head gasket but even that should show in a pressure test.

Wrenchtech
Feb 3, 2012.
Hi, thanks for the reply. The pressure test has shown no errors. (Twice) Are there any other places I can check for leakage? Hyundai told me to monitor it again for two weeks and then they'll check further. But not sure what can be checked any further. Any signs I can look out for?

Tiny
Koala123
Feb 3, 2012.
They just didn't spend enough time pressure testing. Like I said, the pressure test will show anything other than the cap because that is where it attached. It's just a matter of how hard they look. Those guys get paid on flat rate and have no incentive to spend any extra time looking for a leak. You could also have a chemical test done to check for a blown head gasket.
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Wrenchtech
Feb 3, 2012.

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