1997 Johnson/Evinrude EU 25, 35 HP 3-Cylinder outboards Service Manual, Page 268Get this manual
IMPACT RELIEF 1When the engine hits an underwater obstruction, extreme pressure develops above the piston 2The extreme pressure must be vented and the cylinder rod must extend to allow the engine's gearcase to clear the obstruction3Under extreme pressure, five IMPACT relief valves and one UP relief valve fluid to pass through the piston as the cylinder rod extends
will open to allow