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Currently own a Vauxall Corsa (diesel), that is seemingly leaking engine coolant. Having bought over 3 bottles of coolant this week, and having to fill it up constantly, I will be taking it into a mechanic this weekend to see what's wrong. Because of this leak, the engine temperature warning light constantly lights up as the coolant runs out.

To save the expense of further bottles of coolant (and seeming that it's just leaking out anyway), and just as a temporary measure, can I simply use water instead? We are in the UK, so the temperature here currently is of no concern for anti-freeze.

Would this cause any damage in the short term? Depending on the fix, I might not be able to afford the repair straight away, would water cause an issue for a few weeks of driving? (Not major mileage, maybe 15 miles a day).

PnP
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You can run with water in the system and the pressure cap will raise the pressure and therefore the boiling point of the water so that will be fine.

The issue you will face is that the “anti-freeze” is not only to prevent freezing, but it has corrosion inhibitors in it to protect the various metals used for the engine block, water pump and vanes and radiator.

You should get this leak fixed as soon as possible and get the correct coolant fluid in it, mixed in the correct proportions.

Edit re the temperature change caused by antifreeze : yes the antifreeze will cause the water mix to boil at a higher temperature - about 10 degrees F or some 5 deg C - the temperature difference caused by the pressure difference will cause the boiling point to go up to about 120 deg C ie 248 deg F...

Solar Mike
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This is such a complex topic. I suggest you read this entire article about the topic. I learned SO much from it, and I'm sure you will as well.

From my experience, you will be OK using distilled water. (Make sure it is distilled, absolutely not water from the tap!)

Most race tracks only permit cars and motorcycles to use only water, in case there are spills on the track (antifreeze is very slippery). So I'm sure using straight water will be fine in a daily driver. Just keep an eye on how much water you have in the system. The worst thing you could do is let the water level get too low with the engine running.

To try to prevent corrosion, you could add 1 part antifreeze and 10 parts water whenever you top the system off. I don't know how the antifreeze prevents corrosion in the engine (snake oil??), but since most manufacturers suggest a 50/50 water/AF mixture, keeping a small amount of AF in the system will certainly help.

sam
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