On 27 Oct 2006 06:56:13 -0700, "
wrote:

Yes, this is exactly what the marine mechanic proposed to me when I
brought the lower unit to his store. One question that I would like to
ask you: Do we need to re-apply the heli-coil insert whenever we
replace the bolt (like when we need to replace the impeller)?

Quoting from he

http://www.emhart.com/products/helicoil/standard.asp

"Screw-Lock Inserts positively secure threaded members against
loosening caused by vibration and shock. They have a high reusable
factor due to the exclusive HELI-COIL Resilient Screw-Lock which
permits frequent removal and reassembly of bolt without appreciable,
loss of torque."