Ernest Scribbler wrote:
wrote
each broken bolt went through a threaded hole in
the water pump base into another threaded hole in the lower unit. Seem
like the threaded holes in the water pump base had some chemical
reaction with the bolts, and the threads in the hole in the water pump
base had completely corroded away

Take a look at a new water pump base for reference. I'll bet there aren't
supposed to be threads in the holes. (Doesn't make sense mechanically to run
a bolt through one threaded hole and into another.)

I don't have a new water pump base yet. I will get it next week.

When I examined the holes for bolts in the old water pump base, I saw
thread in the holes. They were really corroded. Moreover, the bolts
also had thread in that area. And yes this is kind of strange; I am
wondering how the thread in the water pump base will match up with the
thread in the lower unit underneat the water pump base.

One possibility is that those "thread" in the old water pump base may
not be "real" thread. They may be a corroded surface that mirrors the
thread in the bolt.

I ended up messing up the thread in one of the
hole in the lower unit (the other three are fine). I don't know what
is the best way to deal with this. I will bring the lower unit to a
marine mechanic in this afternoon to see if he can help.

The standard way to fix something like that is with a heli-coil insert.
http://www.emhart.com/products/helicoil.asp

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)? Thanks
for any info in advance.

Jay Chan