Soon after her arrival at Key West, the crew discovered corrosion in the main hydraulic system which forced Bumper to return to the Electric Boat Company for repairs.

Although she searched for Japanese ships, her primary mission was lifeguard duty off Formosa and Hainan Island in support of Allied airstrikes there.

On 6 June 1945, the submarine USS Bugara (SS-331) relieved Bumper, which made for Subic Bay on Luzon in the Philippine Islands.

There, she sighted and pursued a Japanese convoy of two small tankers and a cargo ship screened by a destroyer and several smaller escorts.

Bumper departed Subic Bay on 7 January 1946 and proceeded to San Diego, California, where she arrived on 4 February 1946 and began repairs.

Repairs completed, she spent April 1946 in intensive training, and on 6 May 1946 she headed for her new home port, Pearl Harbor, and reported for duty there with Submarine Squadron 5.

After two more months of training, Bumper′s crew, although cut to 75 percent of authorized strength and with a few United States Naval Reserve personnel remaining, was deemed ready for duty.

Until the end of July, Bumper operated in routine exercises in the waters of the Hawaiian Islands in a stepped-down post-World War II environment.

After overhaul at Mare Island Naval Shipyard at Vallejo, California, from August through October 1946, she returned to Pearl Harbor, where she participated in training exercises in Hawaiian waters with other squadrons.

She made a second simulated war patrol, conducting antisubmarine warfare drills with the seaplane tender USS Salisbury Sound (AV-13) while making port visits to Hong Kong, Okinawa, Sasebo in Japan, Tsingtao, and Midway Atoll.

The submarine was transferred to Turkey on 16 November 1950 under the terms of the Mutual Defense Assistance Program and commissioned that day in the Turkish Navy as TCG Çanakkale (S 333).