74 mercury 9.8 110 - slips into gear from neutral

[rstier]

Hi,
I have a 1974 Mercury 9.8 110 and it occasionally slips into gear from neutral and then back to neutral. Does it sound like an issue in the lower gears or something simpler? Other than that, everything is fine. It never slips once in gear.
Thanks,
Ron

 

[kimcrwbr1]

There is a detent on the horizontal shift shaft that is supposed to hold it into neutral. The shift lever should have the same throw from neutral into forward and reverse.

 

[kimcrwbr1]

http://www.marineengine.com/parts/m...795658-thru-4839253-usa/shift-control-linkage
#11 is the spring with the engine off spin the prop while shifting gears but do not turn the engine over when the gearbox is in neutral the spring should be down into the detent groove I believe the spring is adjustable just loosen the two screws and slide the spring into the groove and tighten it down.

 

[kimcrwbr1]

http://www.marineengine.com/newparts/part_details.php?pnum=MER76994
This is the part the spring holds it into the respective position I have seen them worn out and a real pain it the butt to change not much room to work with and corrosion a big issue.

 

[rstier]

Excellent, thanks for the suggestions, I'll check it out now. Thankfully I'm at the lake and it is warm.

http://www.marineengine.com/newparts/part_details.php?pnum=MER76994
This is the part the spring holds it into the respective position I have seen them worn out and a real pain it the butt to change not much room to work with and corrosion a big issue.

 

[rstier]

So I verified the #11 detent spring is doing what it should and holding the shifter in place. When it jumps out of neutral, that spring is still securely holding in the detent groove and the shifter doesn't move out of neutral, even though it goes into gear. Maybe an issue in the lower?

 

[rstier]

I also verified Part #15 (Gear) in the attached diagram, doesn't move either when it jumps out of gear.

 

[kimcrwbr1]

http://www.marineengine.com/parts/m...thru-4839253-usa/drive-shaft-housing-assembly
#23 is the shift lock cam the upper and lower shift shafts splinr into the cam. Does the motor lock down in when you shift into reverse?

 

[kimcrwbr1]

http://www.ebay.com/itm/1974-MERCUR...ash=item4d3a8f2590:g:LgUAAOSwT5tWMp-C&vxp=mtr
I prefer power steering fluid as a liquid wrench put a couple drops on all of the pivot points on the reverse lock under the clamp bracket. The reverse cam mount and rod are made of plastic and wear out also and are a major operation to replace you dasically have to tear it down completely to get to the cam. A sticky shift lock will cause the cam and bracket to wear out and break. Hopefully loosening up the parts under the swivel bracket will help?

 

[rstier]

The motor kicks up when in reverse, so the lock down is not working properly.

http://www.marineengine.com/parts/m...thru-4839253-usa/drive-shaft-housing-assembly
#23 is the shift lock cam the upper and lower shift shafts splinr into the cam. Does the motor lock down in when you shift into reverse?