Posted by John Swensen on June 26, 2001 at 14:59:43:
In Reply to: HELP !!! posted by mike on June 26, 2001 at 13:17:22:
The PT-6P (and Nirschl, and Hirsbrunner) pistons all use a plastic guide with a metric, M3x.5 thread. Having a few in your emergency kit wouldn't be a bad idea.
The first thing I would do is to follow Philip Moore's advice and move the bad guide to the fourth valve. You might be able to get the broken part of the guide out using the point of a pin. It is possible that, by leaving (a very small) part of the broken guide's threads protruding from the valve, the valve will work for a while. You might need to file (nail file?) the sides of the protruding threads to clear the slot in the casing (be sure to do any filing with the guide out of the valve!).
A hobby shop that deals in R/C airplanes and cars might carry plastic, M3x.5 screws, from which you could cut off a threaded piece and screw this into the valve, filing if necessary. If you can't find the right metric screw in plastic (the originals are white Delrin, but nylon or glass-filled nylon would be fine for a temporary repair), a plastic 4-40 screw might work (it might also break off in the valve, which would be a minor nuisance to remove, but not a big deal).
Good luck!