[Shotimes] Overheat/Gunk in coolant

[Steve Tatro]

I may have a serious problem.

My SHO's been running a bit hot lately, although I've never let it overheat.

I finally looked into it last night, and replaced the ECT, the t-stat, the temperature gauge sender and the radiator cap.  I've been really good the whole life of the car to keep fresh coolant in the system...never let it get too old.

The water pump is about 2 years old.  The radiator was replaced about 5 years ago, as the original had corroded from the inside (I'm blaming the original owner).

This morning my low coolant light came on, and I had some 50/50 in my trunk (since I had just worked on the cooling and lost some fluid).  I opened the reservoir and at the bottom was some greenish-brown gunk...actually looked a bit gritty/grainy...kinda hard to describe.

Thoughts?  I guess my worst fear is a blown head gasket.  I figured if this was the case all the coolant would be brown.  When doing the work last night all the coolant that leaked out was still nice and green.  Also, even with this "gunk" in the reservoir, the coolant that's in the radiator itself (judged by removing the cap and also by letting some drain out the drain plug) is nice and green.

HELP!

Steve Tatro
Red/Black '93 with 178k miles
Monroe, Ohio

P.S.  Anyone know of a good old SHO for sale?!?