Can't shirt into forward 3.7 Mercruiser

[MTBoat]

My 1988 Sunrunner with 3.7 and Alpha one suddenly without warning would not shift into forward. The control is a non branded pull out single lever style, looks like a UFlex pull out model maybe.
Did not see any issue with linkage around engine, and could not get to see inside shifter to see if a bolt fell out or what. Oddly after much trying things, when I tried to shift forward, I could hear a little grinding sound, or then it would even go into reverse....and if I shifted to reverse it would go into reverse.
Anyone with experience have an idea where to start or what is likely?.
It did not seem like the out-drive itself, which seems in really good shape and lower hours, would suddenly not shift.
This all happened after naviating some pretty rough seas, and bouncing around, whether it is related or not??

 

[Bt Doctur]

locate the shift plate on the port side of the motor and have someone move the control lever, report back with results

 

[Fishermark]

Well... something broke. Open the engine compartment and see what moves and what doesn't when you move your shift lever.

 

[Speakrdude]

Does it shift easy when the engine is off?
If so, check your Shift interrupter circuit.

 

[MTBoat]

Thank you all for now, good ideas, I will try over next couple days some of these things,and report back.

 

[thumpar]

The shift interrupt only comes into play when shifting out of gear so that shouldn't effect going into gear.

 

[MTBoat]

I went out and tried with key on or off and no difference, but going into forward just seem to get throttle.
However at the plate where shift cables are attached, it seemed to me that the cables went just about the same distance when I put in reverse, which works, as when I tried to put in forward, but nothing engaging in the lower unit in forward..?? Is it possible a cable connection broke down there and affects one way only, or worse likely?

 

[Fishermark]

I went out and tried with key on or off and no difference, but going into forward just seem to get throttle.
However at the plate where shift cables are attached, it seemed to me that the cables went just about the same distance when I put in reverse, which works, as when I tried to put in forward, but nothing engaging in the lower unit in forward..?? Is it possible a cable connection broke down there and affects one way only, or worse likely?

I don't understand what that means.

You have two cables coming from your controller - a throttle cable and a shift cable. The shift cable should move when you shift into forward and reverse - and should be evident if it is moving or not.

Try disconnecting the lower shift cable - leading to the outdrive - and see if you can pull and push that cable.

 

[MTBoat]

OK, thanks for the next step, I will try that tomorrow and post back what happens. Sorry for any confusion in explaining.

 

[MTBoat]

OK, thanks for the next step, I will try that tomorrow and post back what happens. Sorry for any confusion in explaining.

 

[Bt Doctur]

if the shift plate looks ok, you`ll have to pull the drive to investigat further

 

[salty3rd]

A similar situation happened to me this year; Before you pull the drive; fully tilt up the outdrive and reach up, or look, underneath the outdrive and make sure the linkage going from the transom assembly to the outdrive is seated properly. The shift arm coming out of my outdrive was to low and not making up to the shift arm in the transom assembly.

 

[missalot]

Sounds real similar to a problem I just had to fix on our boat. The lower shift cable (from the engine to the drive) housing had come undone from the brass fitting on the drive end, this allowed the housing to move, not forcing the cable to do its job.

 

[MTBoat]

Found the problem: Upon inspecting the shift cable at the lower unit area, it seems the cable casing had become stressed and opened up, thus not giving the needed pressure to shift properly into forward. Thus, ordering a new cable, all new bellows and parts. Thanks for all the help and input.

 

[Fishermark]

Glad you found the problem. Good luck with the repair!