A904 Lockup Converter Won't Unlock

jhawk said

Thanks man, can you expand on this I'm brand new to these transmissions? Are we talking about the clutch inside the converter and if so is there anything to do other then throw in a new converter?

Thanks,
Jim

Click to expand...

The converter clutch is applied by trans fluid hydraulic pressure, and a piston shaped like a ring.
If that ring gets cocked sideways, or jams on debris it can stick in the applied position.
I have unstuck them by light/medium multiple taps on the converter around the circumference closest to flexplate edge.

That works sometimes and sometimes not.
Multiple on/off switching of the lockup function can also free them.
The only other thing I have seen work is to add a bottle of LubeGard.
This additive is highly regarded for its ability to free sticking valves in automatic transmissions.
It’s a friction modifier used in many trans shops, and can solve a variety of issues.

Sometimes the clutch material comes loose from it’s backing and stacks up jamming the clutch in the applied position.
There is no fixing this unless the converter is sent in for disassembly and repair.