Removing Stuck Pistons from Two-Cycle Headless Cylinders
May/June 2001
Richard A. Day Jr
Copyright Retained
Before starting to remove a stuck piston from a cast iron
antique headless cylinder, it is important to understand that
antique cast iron is not cast steel. Much of it when broken is
quite black as compared with modern so-called cast iron, which is
typically light gray in color. A good way to determine if that
rusty cast iron antique toy is genuine or a modern reproduction
someone buried in a manure pile to make it appear old is to file a
small area. If it turns up gray don't pay an antique price for
it, as it is probably a modern reproduction.
Antique cast iron is much like a ginger snap cookie in that it
breaks quite easily, particularly if the stresses on it are
not reasonably distributed over the entire casting. This
explains the problem of welding cracked cast iron unless it
is heated uniformly and cooled under controlled
conditions. It is far better for an amateur to repair a
cracked water jacket with an epoxy compound than risk further
cracking, or worse, wrecking the cylinder by welding or brazing
without proper heating and cooling.
The following are the successful methods I have used to remove
badly stuck pistons from headless cylinders. There are other
possible approaches, but having unfortunately learned the hard way
I now stick to the techniques that have succeeded for me without
destroying anything.
There is one technique I have always wanted to try but not
having an atomic power plant with its endless supply of boiling
water I doubt many will be able to take advantage of it. It seems
that some success has been obtained by boiling the cylinder in the
cooling water of the power plant for 24+ hours and the story goes
the piston just fell right out. I wonder???
The easy way to move the piston in a headless cylinder is to
fill (leaving no air pocket) the area above the piston with oil.
Plug any ports. Adapt a grease gun fitting to a bushing which is
screwed into a spark plug hole. A few squirts of grease from the
grease gun will generally move the piston with a minimum of stress
on the cylinder and piston. This presumes of course that the
cylinder walls below the piston skirt have been cleaned of any rust
buildup and lubricated with one of the penetrating oils such as
WD-40 or equivalent. Unless there is a space between the piston and
the cylinder wall, I have had little success with any of the
penetrating oils succeeding in breaking the rust seal until the
piston has moved a few thousandths. It is prudent to dig out as
much rust as possible between the piston skirt and the cylinder
wall as there is a normal gap of a few thousandths. (More than a
few thousandths in a badly-worn engine)
Page: 1 |
2 |
3 |
4 |
5 |
6 |
Next >>