I''m a mechanical engineer and being very familiar with
pump mechanical seals and packings as related to industry I thought that switching to a premium brand pure teflon packing would be a smart move. NOT!!! I replaced the old worn out flax/wax packing in my Mirage 29 with its Volvo 2 cyl. diesel and 1" dia. prop. shaft in the Spring of ''99 and had nothing but leakage problems throughout that season. I conferred with
pump experts who agreed that shaft rpm/fpm was well within the acceptability of the teflon packing. The shaft and gland/nut were in great condition. In theory it should have worked but it dripped at an alarming rate and got progressively worse with each passage under power. Repeated gradual tightening only succeeded in extruding the teflon out the gap between the nut and shaft. I finally broke down and changed back to cheap flax and wax packing while still in the (fresh)water. Instant success! A little initial tightening and then one follow-up and scarcely a further drop in the bilge even at 2500 rpm and hours of running. It seems that the tried and tested flax swells enough to provide the right compression without overheating and with no further tightening. In this case modern technology is not the answer!