I doubt that is true. Sure, there were QA issues in Soviet armament, but saying the average service life of T-34/76 engines was "about 100 hours" across the board is not supported by the observable facts. It might be more accurate to say "some (ie a few) examples of T-34s, under certain conditions, or from certain sources were of indifferent quality".
T-34s, properly serviced put together and run correctly were extremely reliable. Tanks built at the end of the war were still operatiing 35 years later.
Compared to german equipment, T-34w were very reliable. How many Panthers at Kursk remained operational for more than a few days, breaking down rather than being knocked out. Out of the 200 or so committed, less than 40 made it from the rail head to the battle area. Does that mean we should say the panther was a low quality tank, or suffred relaibility issues.....of course not....just that initial batch had problems....
During the opening phases of Barbarossa, after only about 1500 miles per tank, what were the avergae servicibility rates of German tanks operating in the eastern Front conditions? Does that make German tanks unsuitable across the board to the East Front conditions....no there were spares issues in that firstr camapaign and engines were not protected from the extreme conditions (cold, dust and power demands mostly)....but I would not say the german tanks were unrelaible or unsuited. They just needed to be adapted a little to suit the conditions. Same deal with the T-34.
There were reasons for these equipment failures on the eastern front. And whilst Soviet QA was somewhat lacking, ther was nothing wrong with the design, and the QA issue was a minor factor in the short life spans of engines. Its just another examp0le of a beat up in this place to try and pedal an agenda I suggest