“I can’t explain it right now,” the Briton, still second in the world championship but now 13 points behind Ferrari’s Sebastian Vettel, told reporters.
“We’ll do some work over this week to fully understand it. I have some feelings about how it (the car) felt in the race and qualifying, I have some ideas. Lots of work will be done to figure it out.”
Hamilton arrived in Sochi as a two-times winner at the Olympic Park street circuit, a track where only his Mercedes team had won since the first race there in 2014, but he struggled to find his rhythm.
Bottas, who had largely the same set-up, was consistently quicker and out-qualified him for third place on the starting grid behind the two Ferraris.
While Bottas made a scorching start to seize the lead into the first corner, the triple world champion was feeling the heat.
“Why is my car overheating?” he asked at one point. “I’m out of the race (to win) now,” he added, with about two-thirds of the distance remaining.
It was the first time that he had finished off the podium since
“In the race I had overheating, but I think I could have kept up with the guys ahead. But I should have been further up with better pace in general,” he said. “And that was lacking from Saturday onwards.
“From probably lap five onwards, I had to just slow down and stay in fourth (place). A lot of turning down of the settings and (power) unit, and then one of the cylinders was cutting because of the temperature issue.
“So, I was going to be fourth from very early on.”
Team boss Toto Wolff said Mercedes had not been able to give