I think that on a Yak-52 installation some similar system exists which disconnects the starter when it meets with too much resistance.
Not so. The Vendeneyef M14P in the Yak52 doesn't have an external starter motor. It starts by admitting compressed air into the cylinders via a pneumatic distributer to drive the engine round.
From the pilot's point of view, after priming you press the starter button with the mags off. There is a loud 'pop' as the air solenoid valve opens, followed by an asthmatic wheezing as the prop jerks slowly round. The button also activates the 'shower of sparks' magneto, so the engine eventually fires up on a couple of cylinders at least, wherupon amid clouds of smoke the mags are switched on and button is released. Vigourous pumping of the primer may be required before the engine becomes self-sustaining.
The particular problem with hydraulic locks is becuase the inlet pipes actually extend furher out from the engine than do the internal bores of the cylinders - they attach to the heads near the top of each head. So on the lower 3 cylinders the internal bore of the pipe is lower than the inside of the head, so oil can collect there. Because it is below the level of the heads, and therefore the exhaust valves, pulling through will not remove it. If the engine is started with oil in the pipes, the oil will be drawn into the cylindr and cause a destructive lock.
To overcome this, the inlet pipes of the 3 lower cylinders have drain plugs fitted at their lowest point. If the engine has not been run for a while, the cowlings should be removed and these plugs unscrewed to drain out any accumulated oil.
If a lock destroys a cylinder on start up, that is bad news. But far worse news is a 'partial lock' Here, there is a hydraukic lock which is just sufficient to bend the con rod. The engine will run OK for maybe many hours, but now contains a time bomb. At some point that con rod will fail, and may take the whole engine with it. That is *very* bad news, and is why, if you run an M14P, you must be very, very careful of hydraulic locks.
SSD