On Sat, 17 Jan 2015 06:19:03 -0800, Larry Jaques
wrote:

On Sat, 17 Jan 2015 07:56:15 -0500, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
. ..
On Fri, 16 Jan 2015 12:43:32 -0500, "Jim Wilkins"
wrote:

...
The standards are a compromise between the need for coarse tapped
threads in weak materials like iron and aluminum castings and fine
threads on screws to maximize the root diameter for strength. That's
why we have coarse and fine pitches. Metric standards are in between
and not ideal for either, as you'd learn fixing motorcycles.

One learns to use anti-seize on steel bolts going into aluminum
housings, too.

I've considered removing and coating the accessible fasteners when I
bought a new car, and decided against the risk of breaking a machine
that's under warranty since the torque specs in the shop manual are
for dry threads.

Instead I sprayed the engine and underside with LPS-3 in the hope it
would seep into the thread gaps enough to keep out water. Generally
they have loosened easily when I did need to remove them years later,
but a few hidden ones rusted and were much harder to remove.

Didn't the waxy film of LPS-3 (I've not used it yet) cause the engine
to act like a dirt magnet?

I bought a tube of aluminum anti-seize back in the '80s to install
spark plugs into aluminum V-6 and V-8 heads. Since then, I've used it
sparingly and infrequently, so that same tube is still my supply. It
sure works well on everything I've used it. I'm glad, because I
absolutely hate galling of s/s on s/s hardware and stripping aluminum
threads/ruining high-dollar parts.

For stainless fasteners in aluminum in marine service, I started using
a Loctite brand zinc antiseize. Expensive, but we'll see next time I
have to remove a fastener. Surely better than all the drilling out,
etc. to remove broken off ss in aluminum. When I rebuilt the
trim-tilt on my outboard, over half the ss bolts broke off, even with
several weeks of intermittent heat/penetrant treatment. Which is why
boat shops only replace the entire unit for several boat bucks.

Pete Keillor