coolant sludge??

[olds_kool]

bought another cheap a4 1.8t, dodgy bodywork and oil light flashing after about 1/2 hours driving
following byzans thread from a few weeks ago i managed to change oil pump (hardest part was cleaning sump out!)

anyway when i pulled off top radiator hose a brown sludge came out (looked exactly like very thick chocolate milkshake)
anyone got a clue what it is or what caused it?

 

[aragorn]

Mixing standard antifreeze and original G12 coolant is the usual cause. G12+ is supposed to handle mixing better.

You'll need to properly flush the whole system and refill with proper red OAT coolant.

 

[Matt82]

thats what i thought too

 

[olds_kool]

thats what i was hoping it was, had head gasket failure going through my mind though
will get the hose on it and cross my fingers

 

[Geeman]

If it's brown sludge, it'll be the coolant mix scenario. Nothing too much to worry about and recoverable from.

You should worry if it's a light cream colour, like mayo. That's a sign of the head-gasket not being happy.

 

[gavinsky23]

I had this and thought head gasket. Once I looked into it it was the oil cooler. Apparently it's much more common on these. It was only around £30 from euro car parts and an easy change, worst part is flushing the coolant system out. It happened after changing my oil pump, I think the increased pressure from the new pump prob caused it.