Andrei, The propellor on your motor has a rubber hub inside the shaft attachment area,Ring,Prop clutch Part #310331 and the plastic Clutch Hub - part # 398316 This is to absorb the blow when the motor strikes an 'immovable' object, The hub tears away and the gearcase is saved the brunt of the blow. It is very hard to tell when these go bad and the scenario you describe may be related to this or a bad shear pin. If the hub is bad they are replaceable as a separate part (I have never been able to get one out of the prop itself without destroying the rubber hub) or it may be a good time to replace your prop with the OMC 'high thrust prop - an aluminum flat bladed large blade model - Not sure of its part number -hidden away on the hub inside. Your motor should be submerged to ABOVE the (lowest) 'cavitation' plate and probably somewhere between the two plates but NOT near the exhaust 'muffler' outlet (plastic block attached to the rear of the housing up above both plates-closer to the powerhead itself). The 'hot' coolant water and a small amount of exhaust will exit right above the propellor at the lowest plate, the balance of the exhaust and some coolant water will exit from the black plastic block - if you EVER see just exhaust and NO water coming out the upper plastic block at the lower unit - shut the engine off IMMEDIATELY and let it cool. Plan on checking the water pump for failed impeller and have the water pump serviced before using the engine. (Good outboard mechanics can be expensive - bad mechanics cost even MORE!) If you can give me your model # I can make a copy of the parts list for you. Good luck - GaryO M-17 # 316a LB/GF! In a message dated 7/19/2008 7:35:32 A.M. US Mountain Standard Time, andreic@math.wisc.edu writes: Hello all, I have a question on my 4hp Evinrude outboard. Yesterday, in a no-wind situation, the boat (M-17) was barely moving with the power at maximum. Maybe I was getting 2 knots, at best. What did seem strange was that when I moved from one side of the boat to another, the prop seemed to rev up, as if just by shifting the weight and lifting slightly the motor, the prop was about to cavitate. As it is mounted right now, on the original (1982) motor mount, the motor is in the water up to the bottom cavitation plate, just above the water pump intake. Is the problem the motor itself, or the fact that the motor is not deep enough in the water? It seemed to run fine except for the lack of power/speed. It is the original motor that came with the boat, 1981 Yachtwin, the boat is 1982 M-17. To give you an idea, with my Compac 16 (lighter, 1100 lbs versus 1600, but still), a Johnson 3hp was pushing it at hull speed with only 60% power. Thanks for all input, Andrei. _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats **************Get fantasy football with free live scoring. Sign up for FanHouse Fantasy Football today. (http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020)