Steve and other list readers.
I've found a job in Decatur, IL and have not set up
a computer yet. So I can only respond to listers
Before going though the effort of removing the heater
core, why not bypass it. Join the hoses with a simple
brass pipe and hose clamps. If your leak disappears,
then at least you know who's the culprit. At the rate
you are adding water, it should be obvious.
Also if your Tiger is running a bit hot (whose don't)
it will normally belch out fluid if your fill the overflow
tank to the max. Let it lose some fluid and then
see if it stabilizes.
Just my first thoughts.
Dave Johnson (working after 13 months of layoff)