Mercury 40 4hp 2cyl, 2 cycle will not shift after water pump change.

[fun4shure]

I have a 1973 Mercury 40 (GNAT) 4hp that will not shift after i replaced the water pump impeller. Is there a secret to how the shift rod needs to be positioned into the gear case to allow for Neutral/Forward shifting?? Thanks for any help on this issue. Hank

 

[nickcunn]

That's not good. When I changed mine and reinstalled. I had my gears locked in forward and I rotated prop on reinstall.. see if that helps you any.

 

[Texasmark]

I had a 4.5 single years ago and didn't do any maint. However, Merc uses a splined connector on it's shift rod to connect to the splined rod emanating from the lower unit. The shaft turns a shifting cam through 3 distinct positions for FNR. You have to have your shift lever set to the same gear that you select on the LU shaft for it to work properly. Some like F and F so you can use the prop to line up the drive shaft and powerhead, and others (like me) like N and N as I have remotes and N is more distinct for me to get everything aligned. However, in N you have to rotate the flywheel to get the engagement as the prop free wheels.

HTH,
Mark