Coolant at engine rear / yellow sludge

[s3tby]

Hi all,

I'm losing around 0.5l every few hundred miles. I've been adding back and no I'm not adding G12 each time!

Had a nose today found a puddle resting at the rear of the engine. The coolant temp sensor all appears to be bone dry so I'm at the conclusion, sadly, that the problem is the rear coolant flange.

http://www.a4mods.com/index.php?page=webcontent/pages/coolantflange.html

However in investigating I removed the PCV valve and then found yellow mustard sludge in the pipe with water sitting on top of it. Are these two issues likely related in some way?

Thanks for any replys!

 

[Mike_B]

I would suspect your analysis is correct. Most probably the coolant flange. As to the sludge, I had similar (clearly seen in the header tank) thanks to my garage mixing different types of coolant. I don't know what was in there when I got the car of course, probably Audi's finest. I don't know what they put in, but the result was gunk. Anyway, having had a new waterpump, timing belt etc, the whole lot was replaced with whatever they use, and the problem hasn't returned.