Wilf,
Just a suggestion as I am sure you have already checked this. I fought the very same type leak for a year and finally in desperation I got my torque wrench out and checked the head bolts along with all others. I found several that had backed off as much as a pound. I retorqued all of them and that was about 2 years ago and I have never had a drop of water leak since. However I now go over the car on a regular basis and check the bolts to see that they are staying tight.
Ron
