orange/brown gunk in cooling system

[Ameer Antar]

I'm pretty sure it's not oil. Nothing was separating in the reservoir. I think
oil floats on water, so I should have seen it there. I've never seenthe
reservor overflow, but that doesn't mean it never happened... The brown stuff
was kind of thick, almost like baby food. It almost seemed like rust, but who
knows it could've been carbon. I wonder if the block started rusting a lot
after it sat for a while before I stuffed it back into the car... 
 
I just hope I don't have to worry about it again. Thanks for the comments.
 
-Ameer 


-------------------- Original Message --------------------
From: DeWitt Harrison [six-rs at comcast.net]
To: antar at comcast.net
Cc: Quattro List [quattro at audifans.com]
Date: 3/13/07 7:25:03 PM
Subject: Re: orange/brown gunk in cooling system

 > Have you been able, by the color or texture of the gunk, to
> rule out a small leak between an oil passage and a coolant
> passage at the head gasket? I've had this happen as a consequence
> of head bolts not being correctly torqued (not in an Audi).
> I suppose a change in oil consumption rate would be noticed
> in that event. I've also experienced a head gasket leak where
> the combustion gases squirt into a coolant passage. In that
> case, there was a semi-dramatic coolant overflow from the
> combustion leak over-pressurizing the cooling system.
>
> I bring up these possibilities because, given your having
> changed out so many things related to the cooling system,
> it seems somewhat unlikely that there would have been
> enough of the old coolant remaining in the system to result
> in things getting gunked up due to coolant incompatibility.
>
> DeWitt Harrison
> '88 5kcstq
>