> Are you saying that when you had a small leak, you got the same wildly 
> inconsistent readings - sometimes fine, sometimes maxed out, and changing 
> very rapidly between them?  Also, sometimes maxing immediatley on startup?

I may have mislead you here, mea culpa.

As I think back on it, it wasn't really *wildly* fluctuating. It was
more like an increase in the temp gauge when I wouldn't have expected an
increase. 

Like in stop & go traffic, outside temp about 40, the temp gauge would 
go up to 3/4, yet never into the red zone.

So, I think my diagnosis may not be correct for your specific problem.

Drew