I have an Audi A3 1.9TDi and I topped up the engine coolant yesterday and noticed that the colour of the water is a rusty colour, plus the bottle cap has rusty particles around it.

Is this a problem?

If so, what should I do?

Cheers,

 

Have you flushed the system lately? If not, go buy some coolant flush and follow the instructions to clean out your system. Should include draining the radiator, filling back up with water only, run for 10 mintues, drain again, fill up with water and the coolant flush solution, run the car for a couple of days (6 hours min.) then drain again, fill with water again, run for 10 minutes, drain again, then fill up with coolant/water (50/50) mix and done.

If you want to clean the overflow bottle, take it out and wash it good with some CLR. Make sure you rinse it out good after it's clean.