Mercury 650 grinding gears

[Dotong]

Hi,

ive recently replaced the gearbox on my 650 with a gearbox from a 50hp. while it worked perfect at the start, after putting it on and off a few times i cant get it to select forward neutral and reverse all together. what i mean is i can adjust the cable to select FN or NR it doesnt seem to have the adjustment left to select all three, the throttle kicks in before forward or reverse is selected when i try to get the cable adjustment right for both.
Hope this makes sense!!

cheers

 

[Texasmark]

Re: Mercury 650 grinding gears

Don't know the year model and even if I did, I wouldn't know about the lower units similarity.

It says something that you had it working initially. Also, I don't know if your control box is single or dual lever.

I'd divide and conquer. Take the remote cable off the shifter in the engine and move it out of the way. Set the throttle lever to idle in case there is a linkage interaction in the enigine.

Put the shift lever in the engine to the different positions FNR and check the prop to see that it responds.

N: Prop spins freely
F: One direction prop can turn engine if you push hard enough, other direction the overrun clutch activates and you can't turn anything but the prop and you hear the clutch...click, click, click......

R: Slowly rotate the prop as you move the shift lever to engage the shifter in the lower unit. Don't force it....when you get the shifter lined up the shift lever should easily move on back to the R position. Once engaged, attempting to turn the prop in either direction results in attempting to turn the engine over....hence resistance both directions.

If that works out ok, your problem is with cable adjustments or problems in your control box; especially if you have a single lever remote control box. If The FNR test failed, the problem is in your lower unit shift cam/pawl or the clutch dog riding on the propshaft.

HTH,

Mark