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Q: Leaking coolant

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Thank you reader for your time

My car leaks coolant, used to be refill every week, now it's very day. We went to the Audi garage, they applied pressure, but they didn't find anything, I don't think it's the water pomp, since it's been changed twice the last 4 years and didn't help. It's a 2002 Audi A6, 1.9 TDI. Some hoses have been changed, pressure has been applied to look for leaks internally, pump has been changed twice last four years. Coolant mix used to be 50/50, now we use more water, since it keeps leaking.

Many thanks in advance

My car has 250000 miles.
My car has a manual transmission.

First of all I’m glad to hear you are just using water. I always advise customers to use just water if they are experiencing a leak and can’t get it fixed right away. My question is did the pressure gauge move while they were doing the test? If it did you may have a blown head gasket. This is the only thing I can think of if there are no visible leaks. Oil and water mixture are not the only ways to know there is a blown head gasket. If there is a loss of pressure in the cooling system you could also have a cracked head which could mean that the coolant isn’t leaking from a place that is normal.

You could also have a clogged heater core stopping your coolant from properly circulating. You may get some dye for your radiator and apply that, pressure test it again and use a black light to find out where the leak may be happening, yellow glasses will help too with finding out where the leak is coming from. Look at your radiator in the front and back and see if you can see any wetness. I once had a customer that couldn’t find his radiator leak, it wasn’t dripping on the ground but he was going through antifreeze just like you are. It turned out that this was the issue. His was a VW which owns Audi. Hopefully this can help you find your problem.

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