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Q: car leaking water

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I own a BMW 750 Li, and I'm only putting water in it for coolant. My car is using up the water quickly. I have to keep adding more water all of the time. I know my car needs to have the original coolant in it, but it had a leak. Do you have ideas or suggestions? Thank you.

A: Hi, thanks for writing in about your BMW 75...

Hi, thanks for writing in about your BMW 750i. Water alone is not meant to handle the cooling of the engine. If only water is used in the cooling system, the water will boil off and become nothing because the engine reaches much higher temperatures than it takes water to boil.

The antifreeze that is added to the water increases the boiling point and decreases the freezing point allowing the mixture to reach much higher temperatures than water alone.

Although you have a leak, you will lose fluid much slower if you add the correct fluid to your cooling system because water alone will boil off. Even if you didn’t have a leak at all, the water would eventually run out and your engine would likely overheat.

I would recommend having your cooling system pressure tested to detect the leak, and then have the leak repaired in order to prevent any further engine damage.

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