Removing Stuck Pistons from Two-Cycle Headless Cylinders

(Page 2 of 6)

May/June 2001
Richard A. Day Jr 
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Perhaps your friendly dentist will give you a few of his or her discarded tools. They are tough and great for getting into tiny cracks and openings.

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The success in removing a stuck piston lies in the preparation. It is so easy to destroy an irreplaceable part; therefore, careful preparation is mandatory.

The hydraulic method is probably the best, least stressful and easiest method to remove a stuck piston. It is possible to break out the center of a piston in those cases where the piston is not particularly rugged in that area. Fortunately most two-cycle pistons have a raised baffle next to the intake port and most are cast as a portion of the piston. The only two-cycle piston I have ever seen where the baffle was riveted to the top of the cylinder is the piston on the first Palmer Marine engine ever made.

The cast baffle makes the piston head much more rugged than in the four-cycle piston. In any case I have never experienced breaking out the center of a piston using the hydraulic method of piston removal.

The one method that will guarantee breaking out the center of a badly stuck piston is putting a steel rod down through the center of the cylinder from the top and trying to hammer or push the piston down with a press.

There are complications, however, that makes a seemingly easy task a real problem. Suppose the cylinder is headless and for a two-cycle engine with the piston head stuck below a port. In this case it may not be possible to seal the port (or ports) so the hydraulic method can be employed.

A small flashlight bulb soldered to a couple of feet of approximately 22 gauge insulated wire coupled to a six-volt transformer makes a great inspection light to get a look inside a water jacket or cylinder where the piston is not removed. It may be possible to introduce the light through one of the ports or the spark plug hole. Small dental mirrors work well in those cases where they will fit through any openings into the cylinder or water jacket. Fragments of mirrors are sometimes useful in trying to get an idea of the condition of the cylinder or water jacket.

If examination of the cylinder wall above the piston indicates only superficial rust, then the following can be used to remove the piston.

This method of removal first pushes the piston further into the cylinder until the ports are covered. Once the ports are covered by at least ' of piston travel, then the hydraulic method is used to push the piston back out to the edge of the ports.

The oil is allowed to drain down and the piston is then pushed back in again, this time perhaps an inch above the ports. The oil is then replaced and the piston pushed back to the edge of the port. At the same time this has been going on, penetrating oil is liberally applied to the piston skirt. In some cases it may take three or four back and forward movements to permit the piston to be totally withdrawn.

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