Tranny issue

[Dff Moriarty]

Had trannny out for quite some time to build engine. Flushed tranny out and installed. Filled with Swepco Blue.
Now tranny won’t stay in second or fourth gear. Just pops back out. Car is on a lift so no issue of having to climb under it so if it takes several steps to diagnose then not a problem.

[Dave at Pelican Parts]

First thing is to go through the linkage. If reverse also has a problem, the linkage is almost certainly the issue. The linkage may be adjusted so the pattern is too far aft, not allowing the selector to go into the R/2/4 gates properly. Or something could be fouling on the linkage (e.g., if you have a partly-done side-shift conversion or something adrift in the center tunnel).

If you disconnect the linkage at the transmission, can you manipulate the gear selector to select all gears successfully? If not, that points to a problem inside the transmission, unfortunately.

But having issues with multiple gears generally points to a problem with the linkage.

--DD