Broken Cylinder base stud - 0300

[Leo O'Farrell]

Hi all,

What would cause a a cylinder base stud #5 or right front cylinder to fail? This is the lower left (8 o'clock) stud that sheered at the base. Turns out this is one of the many through studs in this engine.

In the middle of doing a top overhaul now, and learned the piston pin on #4, on the left bank is coming apart at the ends. This cylinder is on the other side of the of the broken stud, so it also lost torque.

Thanks.

leo

 

[Henning]

Too many possible causes for speculation without being eyes on for me to guess.

 

[Skylane81E]

Over torqued, fatigued?

 

[Tom-D]

Hi all,

What would cause a a cylinder base stud #5 or right front cylinder to fail? This is the lower left (8 o'clock) stud that sheered at the base. Turns out this is one of the many through studs in this engine.

In the middle of doing a top overhaul now, and learned the piston pin on #4, on the left bank is coming apart at the ends. This cylinder is on the other side of the of the broken stud, so it also lost torque.

Thanks.

leo

very typical of the 0-300 high time engine, the cases have fretted and the whole center line seam is loose. The cure for this is a total rebuild getting the cases re-surfaced and line bored, new thru studs, and all new cylinder hold down studs.

The most common cause is the prop is a cruise prop and the engine has been running at too low of an RPM with high manifold pressure.