650 hp Mercury HELP!- gear stripped on driveshaft

[seawolfofspokane]

Hello-<br />well i pulled the "lower unit" off (new term to me....this is my first boat) and discovered the main driveshaft top splines were worn BAD- so is the female part of this assembly (we looked up inside with a flashlight and could see the "teeth" were all worn down).SO ! i solved the mystery of the non engaging propeller......but, My questions are: what do i do now??? is the "gear" up inside of the motor easy to remove? where can i get a new or used driveshaft for this 650 mercury? I think it is a 1966 motor...also something i wanted to figure out. Does anyone know where i can find out what year my motor is?<br />This is such a great site! Ive learned so much-<br />thanks!<br />jon

 

[dinsdale]

Re: 650 hp Mercury HELP!- gear stripped on driveshaft

Buy the manual for your motor.<br />post the serial # and someone can tell you the year.

 

[Chinewalker]

Re: 650 hp Mercury HELP!- gear stripped on driveshaft

More than likely the "splines" on your driveshaft are worn because the mating splines in the crankshaft are rusting out. Not uncommon because people without manuals attempt to service water pump impellers and aren't familiar with the step that calls for the mechanic to "liberally apply waterproof grease to splines at top of driveshaft before reassembly."<br /><br />If you're lucky, the driveshaft splines are the worse of the two sets and a new driveshaft may solve the problem. However, it's more than likely that in order to salvage the motor you'd need to replace the crankshaft, too...<br /><br />- Scott

 

[busboy]

Re: 650 hp Mercury HELP!- gear stripped on driveshaft

The "gear" you're looking at is actually the bottom snout of the crankshaft. If this is stripped the motor is basically junk unless you want to put a lot of time into fixing it. Putting in a new driveshaft is a bear too. Try this website for finding out the model year: http://www.oldmercs.com/ <br /><br />Also this website has a parts breakdown on it and can help: http://www.mercruiserparts.com/select_models2.asp?type_id=MERC