B737 Undifferentiated or Other Model
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 167; Flight Crew Type 6553
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition
Aircraft
This aircraft had a previous writeup [two months earlier] pertaining to the same issue and was put on a [Deferred Item]. On climb out of ZZZ; at 14;000 feet; the stabilizer started bumping the nose of the aircraft up and down slightly. It continued up to FL 240. We were indicating 284k per the FMC and there was no movement with the yoke. I disconnected the auto pilot and bumping of the nose up and down continued. I felt no movement within the flight controls. I turned back on the auto pilot. The bumping was consistent with regular intervals of around 1 to 2 seconds. It was not turbulence that was causing the bumping to occur. My FO (First Officer) and I were uncomfortable with continuing the flight. I notified ATC and requested rescue vehicles upon landing. We leveled off at FL 250; I slowed the aircraft to 250k and the bumping stopped. I handed the aircraft over to my FO. I took at the QRH to see if there was a check list for our flight condition. I call Operations (we were still in radio range) and told them we had an emergency and to please contact my Dispatcher. I called and briefed the lead FA (Flight Attendant) and made a PA to the passengers that we would be returning to ZZZ. I took the aircraft back from my FO and proceeded back the ZZZ. My FO sent the logbook entrees to maintenance via ACARS. We continued to ZZZ at 250k with no further issues and made a safe over weight landing. Maintenance met us at the gate and was briefed. I call my dispatch and briefed them and also briefed two [Flight Operations Managers] on the phone.
B737 Captain reported vertical bounce during climb.