All,
I spent the last 15 years of my career in the aircraft hydraulic pump
business. We used the PYI type face seals for all of our pumps,
electric motor pumps and hydraulic motor driven generators. Many of the
older units used the carbon graphite nose pieces. The newer units use
Tungsten
I have had 0 problems with mine since about 1987. The hose and seal were
swapped out in 2014 I think while the shaft was out as preventative
maintenance. That apparently should have been done in 1994! Anyway, modern
Teflon packing has made the conventional stuffing box pretty easy to deal with.
A few years back, a boat at our club with a drip less shaft seal also
had a sudden and serious failure causing extensive flooding inside the
boat before it got hauled. It happened within an hour after the boat
was launched in the Spring. Someone noticed the boat's bow "boot
strip" was below
