recently my mechanic repacked my stuffing box with graphite. I had teflon before He told me the graphite packing should not drip at all even underway. I've read that graphite disperses heat much better than teflon and drips less but I still had concerns. We left the marina -idiling for ten minutes then slowly got to 1600rpm( 12mph). 5-10 minutes the temps on both seals was over 200F . After drifting for 30 minutes - temps down to 130F. Any increase above idle drove it higher.There was some black fluid bubbling out -? liquifying graphite. I'm assuming he overtightened the stuffing boxes.I want to go back to dripping seals. Appreciate thoughts. OB
I realize there is a company that sells it, and I've contacted them a few times to pose questions with no response, however, graphite should not be used for marine shaft packing. Graphite is
thee most noble metal, place it in contact with almost any other metal, in the presence of an electrolyte (seawater in this case) and it will cause the other metal to corrode.
There are a range of other packing materials, from conventional flax to Teflon, Goretex and others, from which to choose, there's no good reason
to use graphite based packing, and at least one good reason to
not use it.
As far as temperature goes, my rule of thumb is the stuffing box should not be more than 30-40F above ambient water temp at wide open throttle. Temperature is far more important than drip rate, if the box is not overheating that's what matters. Based on your description it sounds as if yours is running hot.
I occasionally find a small pyramid of wax under an overheating conventional stuffing box, that's what happens when it runs too hot, the wax melts out of the packing, as it drips onto the hull beneath it cools and builds a small mound.
More on the subject, including on graphite, here:
https://stevedmarineconsulting.com/conventional-wisdom-for-conventional-stuffing-boxes/
(In Taiwan conducting a new build inspection)