Mercury 850 reverse gear engament issue

[TheGeek]

Hello, I have recently purchased a boat with a blue banded 1973 Mercury 850 85hp motor with the Thunderbolt ignition. Apart from the wiring which I am currently repairing the motor cannot go into reverse. It can effortlessly engage the forward gear and, with a bit of persuasion, disengage and enter neutral, but it can not engage into reverse; the lever on the remote control becomes very hard and the motor won't budge. I've researched and found that it could potentially be a worn "shaft coupler", however, I can not find this part on any of the parts diagrams for the gear housing. The motor sat for two years before I bought it. Any help would be appreciated, thank you.

 

[racerone]

Is the motor running when you try to shift to reverse ?----Or is the prop turned by hand when you try and shift it to reverse ?

 

[TheGeek]

The boat is a project boat and when I got the motor it did not run so I couldn't try it with it running, but I tried it by just spinning the prop by hand but even then by spinning the prop it wouldn't engage.

 

[Texasmark]

R gear is the farthest distance for the shifter components to react. The manual states that if you force/attempt to force shifting to R without something turning (as racerone noted) you can bend your shift mechanism....didn't say where....internally or in remote cables. Shifter for R is a cog slot arrangement and you have to be dead on for the two to engage. Spinning the prop or driveshaft allows that alignment to happen and the shift to engage.

Have you had a look at your lower unit gear oil? If so what did you find? Tell us what happens when you turn/attempt to turn the prop in F and N gears.....you already said that R freewheels.

 

[TheGeek]

So it clicked when I turned the prop clockwise in forward gear, and it turned the driveshaft when turned counterclockwise. Furthermore, i removed the lower unit in order to inspect the internals and the water pump. the oil did not seem to have any metal shavings and there were none at the screw when i drained it. The problem still persisted even after the lower unit was removed. The motor does not go into reverse gear at all, once it is in neutral it's like there is a lock or something is stuck and the control cable won't move any further.

 

[TheGeek]

So for posterity's sake the motor is now able to engage reverse, or more correctly the linkage mechanism can now go to the reverse position; the culprit being a bent control cable at the MerControl end. Thank you all for your help.

 

[Texasmark]

Glad you got her fixed.