I have a problem with my coolant water tank, I was driving along and my coolant level light started flashing on my Audi A6 quattro 2.7T sport 2000 V reg, So I stopped my car and checked the coolant level, it was all gone. I filled it back up and carried on driving, after another 10-15 miles the light came on again. So I filled it back up and it seems that my coolant is flushed out of the tank all at once and then my engine starts to overheat. I have asked several mechanics who said it could be anything, from my head gasket to my thermostat, now I dont want to leave it in the hands of a garage to be told its more than it is and have to pay money for nothing. I just need to know what the possiblilties could be so I know what to rule out or how to tell what it wrong with it.

Matt Auton, September 2008

was the engine temp normal before the coolant light came on?

Andy, September 2008

Hi, Matt,
One possible cause may be overfilling your expansion bottle/radiator. If you fill it to the top, when it heats up and 'expands', then it will overflow and the syphonic action will cause virtually all the water to leak out. There should be a level marker in the bottle or radiator...fill it to this level only. Don't be tempted to fill it to the top. It needs room to expand as it heats up. Also, only fill it when the engine's cold....if you fill it when it's hot, you'll again put too much water in it as the level will be higher where the water's hot. Give this a try. Best of luck!!

Denis Langley (Car Aid Mobile Mechanic), September 2008