I have seen this with thermal expansion.
It could be caused by your neighbor belive it or not.
Are you on city water?
What is the water pressure?
What kind of hot water you got?
Where is tank in relation to this valve?
Is the water extremely hot at the sink?

You claim to be replaceing the seats as well as the washers, in fact it
looks like you have replaced evarything at least once. The problem is
the hot washer wears out.

Are you sure the washer is wearing out?
Is it tearing or getting marred?

At this point I'd start trying some different washers.
You are not putting grease on them right???





"Duane Bozarth" wrote in message
...
tony_g wrote:
...w/ tale of woe subject...

I've not followed this thread, but a comment about grit/sand/etc.,
wearing seat caught my eye---methinks it's quite likely the seat is worn
from erosion from the previous leaking (a very small drip still comes
through the minute area between the seat and washer w/ pretty high
velocity/pressure) and the problem is a new washer can fill the
imperfection for a short time but soon fails.

If possible to reach, you could possibly clean up the seat face s/ a
seat-facing tool if that's the case.