Question: I have a mercury 2.5 (boat engine), the prop stopped spinning properly, with the engine running?

(Posted by: on 2010-08-04 03:43:40)

Last night while out on my boat the engine was started again after going down the river a mile or so. but we was not going anywhere(working fine till this point), I checked for any rubbish on the blades/ prop and found that the prop was spinning freely, as apposed to normally it is tight to turn. the prop was not lose and attached like normal the pins where in, when the motor is started it spins but at such a low rpm it wont push a paper boat, when reved up a little it creates a bit more smoke more than i would like so i turned it off completely, the fuel mixture is correct. after switching everything off and checking with no clue every part i could see to make sure there where no obvious faults the prop was tight again I put it in the water and got it home.. while carrying the engine back home the prop was stiff as usual and was being normal. however when i arrived back it was lose and free spinning once again..i did not knock it or anything and was carried in the upright position. Im certainly not an expert but have no idea why this is occurring? It is hardly used when i got it. any help would be great thanks, I don't have the money to take it somewhere I will have to learn and do it my self thanks in advance. here is the model if it helps: http:/ / www.google.co.uk/ imgres?imgurl=http:/ / www.defender.com/ inflatables/ outboard_project/ mercury/ mercury_2/ images/ merc2_5.jpg &imgrefurl=http:/ / www.defender.com/ inflatables/ outboard_project/ mercury/ mercury_2/ merc_2_5.html &h=300 &w=185 &sz=7 &tbnid=nc_uhKNNw9QS0M: &tbnh=116 &tbnw=72 &prev=/ images %3Fq %3Dmercury %2B2.5 &usg=__axUeFw839IjSMXd6ufLAZ6wIBX4= &sa=X &ei=Dz5ZTKuEComi0gTWkKHmCA &ved=0CDoQ9QEwBg Thanks so much found a nice website now on what the hell im doing and how to fix it step by step it also describes my problem perfectly ahhh my heart nearly stopped. thanks will

Posted by: William W on 2010-08-04, 05:10:19

There is a shear pin behind the prop that protects the engine / prop when an underwater object is hit by the prop. It intentionally breaks (shears) which leaves the prop free spinning. Pick up a few new shear pins at a boat dealer, they're cheap. Then remove the prop and the broken pieces of the old pin and put in a new one. Reinstall the prop.