On a 1995, A6. 2.8L Quattro. Anyone know where the Engine Coolant Drain Plug is located exactly? I see a drawing [ 10-1170 ] on page B 19-9 of Bentley Volume #1 but the drawing is not clear enough for me to locate this plug. They refer to using special tool 3247 to remove the plug.

I want to replace coolant. After draining the radiator by opening the Radiator drain, I only was able to get only 4 litres of coolant to drain out. Yes I measured it. The system calls for 8 litre capacity so obviously 50% of the coolant is still trapped in the engine cooling passages. I would think opening this so called Engine Drain Plug will allow the rest to come out.

Blowing into the expansion tank with the radiator drain plug open got just a few ounces additional out.

Any idea how to get the balance of the old coolant out other than finding this Engine Coolant Drain Plug and opening it?

After more searching I did find the Engine coolant Drain plug and removed it. I used an 8mm allen head on a universal joint socket adapter to unscrew it.

The O-Ring that fits around the plug was torn. It feels soft and pliable enough to be a silicone O-Ring.

I am now wondering if a standard rubber O-ring would be suitable for a replacement or is a Silicone O-ring required because of temperatures over 200F ?


Thanks for any input on this.