orange/brown gunk in cooling system

[DeWitt Harrison]

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

On Tue, 13 Mar 2007 09:17:18 -0400 (EDT)
        Ameer Antar <antar at comcast.net> wrote:

> Well, I never put in the green coolant myself, although there was some in
there
> from the po. After replacing almost every single component in the system,
I
> figured I wouldn't have to flush anything out. That included the engine,
> radiator, heater core, hoses, pipes, transmission cooler, etc.
>
> I used the blue stuff from Pentosin, which is supposed to be the
recommended
> coolant for the early type 44's. This is not the cheap stuff you can at
the
> FLAPS. The weird thing is the coolant used to be blue, but after only a
few
> months it turned orange/brown. I never put anything else in there, so that
got
> me worried. Seems like it's rust or something like exhaust is making it
turn
> colors. I don't think any type of coolant should do that in such a short
time.
> I guess I'll just have to wait and see what happens this time. Hopefully
this
> was just related to the loose head studs.
>
> Thanks for the tips everyone. I'll keep you posted.
>
> -Ameer