Re: johnson 9.5 1968
Hi younggun. Welcome to iboats. It could be a few things. You may have a spun prop and/or a broken shear pin. Either of which could cause the motor to rev without the boat moving. To check, remove the cotter pin holding the prop cone in place, then remove the prop cone. The propeller should then slide off of the prop shaft. If your motor has a hubbed prop, you will most likely have a stainless steel "drive pin", rather than a soft brass "shear pin" which are found on un-hubbed props. If the shear pin is broken, you simply replace it and go on your way. You can buy brass rod at many hardware stores like ACE and cut as many pins as you like. If the drive pin is broken, you'll probably have to order a new one. If the pin looks ok, you have to test the prop for a spun hub by scribing a line across the back of it with a Sharpie and taking it back out on the water. After running at WOT, remove the prop and check the back. If the horizontal line you scribed across the back is no longer level, then the prop is spun in which case you'll need to have it re-hubbed at a prop shop for about $40. However, you may also simply not be going into gear properly. I would check the shift rod connection for starts. If that's ok, you may have a bad/worn clutch dog, which is fairly common. To test it, with the motor off, put it in FWD gear and rotate the prop clockwise by hand. You should feel it engage after about and 1/8-1/4 turn. Repeat the procedure for REV. If the prop engages, that's a good sign, however no guarantee that the clutch dog is ok. The only way to be sure is to take the gearcase apart and visually inspect it. Give these tricks and report back. Here are some handy links to help out.
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1968&hp=9.5&model=MQ-14E
http://www.duckworksmagazine.com/06/columns/max/index6.htm
