Merc 35 (1986) - lost forward/reverse and pumping water

[rstier]

Hi, I was out in my boat yesterday and my 1986 35 HP Merc lost forward and reverse gear all of a sudden. It also stopped pumping water. I paddled back to shore and couldn't notice anything obvious. The prop looked ok, so I assume I have to pull the lower. With the motor turned off, if I put it into gear (forward or reverse), the prop engages and spins freely in neutral as it should. I originally thought it may be the shift shaft, but it does appear to engage in gear as mentioned. I think the fact that it is not pumping water as well may be a good indicator of the problem. Any ideas what I am in for?
Thanks!​

 

[GA_Boater]

If you put it in forward and reverse and the prop spins like it's in neutral, along with no water, there are two possibilities. A broken driveshaft or the splines on the crankshaft/driveshaft are worn to the point of no engagement.

You have to drop the lower unit to see what the story is.

 

[gm280]

I absolutely 100% agree with GA_Boater's assessment. Either a broken drive shaft, OR a stripped spline. I'd take the broken drive shaft of the two possibilities myself... If the splines are stripped and they are stripped in the crankshaft end, then it is a total engine disassembly to repair and costly as well... JMHO!

 

[rstier]

Hi, thanks for the response!

Just to clarify, with the engine off, if I put it in forward or reverse, the prop does engage. Only in neutral does the prop spin freely.

I absolutely 100% agree with GA_Boater's assessment. Either a broken drive shaft, OR a stripped spline. I'd take the broken drive shaft of the two possibilities myself... If the splines are stripped and they are stripped in the crankshaft end, then it is a total engine disassembly to repair and costly as well... JMHO!

 

[GA_Boater]

Remove the spark plugs and shift to reverse. Try to turn the prop - Does the flywheel turn? I still think you will be dropping the lower.

 

[rstier]

Hi GA,
I shifted into reverse as suggested and tried spinning the prop. Unfortunately the flywheel doesn't spin. Thanks for the reminder on the plugs. I need my hands today.

Remove the spark plugs and shift to reverse. Try to turn the prop - Does the flywheel turn? I still think you will be dropping the lower.