Bad crank on Merc 90 hp

[Raider316]

I have a Mercury 90 hp outboard 6cyl. inline believe early 80s sn# 06399494<br />THe problem is the engine runs fine but prop will not turn in forward or reverse. It quit working as I was accelerating and now no longer turns at all.<br />I have determined by removing the bottom half of engine that drive shaft turns prop just fine but the engine does not turn drive shaft. I pulled power head reached my finger inside end cap and can feel no splines inside the power head. (the splines on drive shaft seem fine)<br />I am told that the drive shaft connects directly into the crank shaft which has splines on the inside of one end. Is this correct or does the end cap connect the 2? What are my options since if it is the crank they are no longer available?

 

[briannh1234]

Re: Bad crank on Merc 90 hp

Hi Raider -<br /><br />I have a 1979 140HP. It is all apart right now. I checked mine and it does have splines as part of the crankshaft. The splines are not right at the end - they are about an inch in. The endcap just passes the bottom of the crankshaft thru it.<br /><br />The crankshaft may not be available as a new part - but I have seen them for sale used on ebay. I have a part's motor here that I am planning on selling on ebay that comes with the crankshaft, complete - with splines.<br /><br />Changing the crankshaft is NOT EZ. You may want to look for a used motor or head that runs. They are the cheapest in the middle of the winter.<br /><br />Good luck.

 

[Raider316]

Re: Bad crank on Merc 90 hp

Thanks!<br />Im kinda new at this boat thing so any input is appreciated.<br />Im somewhat leery of a used crankshaft since the wear in differently and I will have to change other parts as well. Is changing it similar to changing one in a car?<br /> If I cant find a good power head I guess my only option is to get a different motor.