Re: bad clunking, u joint? im no boat mechanic by any stretch, but i am a car mechanic. it definately sounds like a u joint to me. given the scenario with pulling it down from drive to fast and maybe even hitting reverse, it sounds like that is probably what did it in. seems like it wouldnt be to terrible to fix, but who knows. i usually take. When turning hard left u joints make a loud chatter noise. when turning hard right u joint make a faint noise that can almost not be heard. recently rebuilt 1992 mercruiser 5.7 (chevy small block 350, v8, 300 hp); bravo 1 outdrive., i did align the engine using and alignment tool.. Re: mercruiser stern drive u-joint noise its hard to tell! we can't hear your drive! but an once of prevention or anual maitenance is worth every penny.pull the drive and inspect them or have somebody do it for you ! i pull the drive on mine every yr before the season starts and at the end of the season..
Sounds like a 3 point mount. if you have an engine hoist, pull the bell housing and remove the driveline. reinstall the bell housing and see if the noise goes away. you can check the torque on the flywheel/ flexplate at this time as well. if you don't know the condition of the universal joints its wise to rebuild the driveline as well.. If the alignment tool does not slide in at one engine rotation position, but does at another, the coupler is either bad or not installed on the flywheel properly. while the drive is off, check and service the universal joints. if one of the u-joints is worn, it could also be a cause of the noise.. In order to use the universal joint shown in the op perhaps the easiest way would be to have the stern gland, which will act as a support bearing, or an intermediate bearing known as a plummer block, firmly attached to the top of the stern tube..
