Mercury 402 Lower Unit Shift Rod Installation

[crazyboutamercury]

I have dropped the lower unit on a 402 40HP Mercury Outboard to replace the impeller for my father inlaw. I tried putting the shifter in forward and rotating the shift rod in the lower unit full clockwise and bolted the lower unit up. The shifter would not return to neutral or definatly not reverse. I dropped the lower unit and again placed the shifter full forward and rotated the shift rod in the lower unit full counter clockwise. Again I could not get reverse or neutral. I dropped the unit again and place the shifter in neutral, and the lower unit shift rod in the center. This time I had forward only. What is the proper proceedure to install the lower unit and have the shifter function properly?

 

[eldplanko]

Re: Mercury 402 Lower Unit Shift Rod Installation

Been though this ordeal a few years ago. Take pictures when you take it apart to help you remember how to put it together.

1. With lower unit off, place control lever in forward gear. The angled parts of the square gear shaft in the upper unit should be in line with the boat/engine. If not, adjust your shift linkage so it lines up correctly. When shifting the shift lever, the shift shaft should rotate 45-degrees for each shift (i.e 45-degrees from forward to neutral, 45-degrees from neutral to reverse).

2. Get a pair of vice grips and turn the gear shaft in the lower unit to forward. Agan the angled parts of the square gear shaft should be in line withe the forward/backward direction of the lower unit. The prop should free spin in the reverse direction and turn the main driveshaft in the forward direction.

3. Test by turning the gear shaft in the lower unit 45-degrees counter clockwise (when looking from the top). It should go into neutral, and the prop should free spin in both the forward and reverse direction

4. Turn the gear shaft in the lower unit another 45-degrees counter clockwise, it should go into reverse, and the prop should free-spin in the forward direction, and turn the drive shaft in the reverse direction.

5. Turn the gear shaft in the lower unit back to forward (90-degrees clockwise).

6. Make sure the reverse lock cam in in the correct orientation, see the picture (note, it's in forward). The lower edge of the cam should be in the "forward" position, and the high edge of the cam should be in the starboard position.

7. Make sure when you reattach the lower unit that lower and upper shift shafts line up correctly.