I guess I missed something but what is the difference if you leave the sea
cock to the engine open or have this line to the packing. I always expect
to leak some water by the pump but expect the vented loop to break the
siphon. It is mounted high above the water line to prevent the flooding the
engine. Now if the vented loop is below the water line or if it is plugged
then all bets are off.

One thing to think about is if the shaft was turning without the motor
running the seal could actually be a small pump and be pumping water back
into the engine via the tube. It would not be a very efficient pump but
might develop enough head to overcome the level difference on the vented
loop especially if you are healed over. If that happens it will flood the
engine.

When I ran a PSS seal on a sailboat I wondered about that so I got the
ventless/tubeless one. One disadvantage to the tubeless one is that you
need to burp the seal to get the air out. Kind-a ends thoughts of a dry
bilge. Burping would be a real pain on my current boat. Currently I am
real happy with the new TFE packing material using a standard stuffing box.

Perhaps someone who has a PSS seal could disconnect the tube at the pump and
hold it at water level. Block the end at the raw water pump and run the
engine in gear at a shaft speed similar to running at hull speed without
engine and out of gear. See if you get any pumping action. If so raise the
tube end higher and measure the elevation at which the surging stops. If
you get a couple of inches you are probably ok. If you get more then that I
would suggest not sailing out of gear without the engine running. Put it in
reverse and consider using the tube as a vent to allow the air to escape.

"Doug Dotson" wrote in message
...
That is assuming that the cutlass is mounted in the end of the stern
tube. Obviously wouldn't make a difference in a strut mounted
cutlass.

I also misspoke about raw vs fresh water coolong. The problem
can occur in either case if you have a mixing elbow type exhaust.

Doug
s/v Callista

"Doug Dotson" wrote in message
...
As I mentioned earlier, the injection feature is a good thing
in any case. It helps keep the sediment out of the stern tube and
helps extend the life of the cutlass bearing. That is assuming it
is installed correctly.

Doug
s/v Callista

"JayCeeCG" wrote in message
...
Looks like your installer also ordered the wrong gland. pss seals are
available with or without the injection nipple.
Jared Crane