Our '91 740 developed a miserable leak in the power steering.

Turned out to be one of the small steel pipes that runs from the valve to the rack body -- pinhole rusted through.

Removed it, washed it out, wire brushed it, ground around the pinhole with my Dremel, and soldered it using plumbing solder and a propane torch.

And painted it.

Works great, at least for my 3-mile test drive.

Fortunately, I had replacement o-rings of the right size (tiny suckers) in my el-cheapo Harbor Frieght "10,000 o-rings fer $9.99" kit.

This is the second time in 8 months that I've had a leak in the power steering from a rust hole. It's that %$#@ing Massachusetts road salt.

Also replaced the exhaust system at 236k miles. The old one was original. (Maybe I shouldn't complain too much about rust...)
--
Don Foster (near Cape Cod, MA)