Hello All,
I am trying to identify a mysterious 'goo' that has shown up in my radiator overflow tank and around the radiator cap. It is a black, sticky, and stretchy substance that can ball up if rolled, but also smeared. It floats as a surface film but as such is completely cohesive in that it tends to stick together and can be removed from the water.
This is causing me concern because I have no idea where it came from. One month ago I had an instance of overheating. I replaced the thermostat and since that time, everything has been fine. Then yesterday, after a good distance of mountain driving it overheated again, but this time fluctuated between Hot and Normal. Today it has been fine, albeit a much shorter driving distance. I am a little familiar with the head gasket issue with this model year and am worried that could be the source of the goo and the cause of the intermittent hot temp, but I didn't think that oil in the radiator would look like, or turn into this type of goo. I am including pictures to see if anyone recognizes the stuff and can say whether or not it is oil.
The Images are below. If they do not show, please check the following link:
I appreciate any help.
Jacob Cooper
1998 Legacy 2.5 GT